diff --git a/CHANGELOG.md b/CHANGELOG.md
index c636f3777..013c9f48f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ _None_
 * Add the option for `an_localize_libs` to provide a `source_id` for each library being merged.  
   If provided, that identifier will be added as an `a8c-src-lib` XML attribute to the `<string>` nodes being updated with strings from said library.
   This can be useful to help identify where each string come from in the resulting, merged `strings.xml`. [#351]
+* Add the option for `an_localize_libs` to set the `tools:ignore="UnusedResources"` XML attribute for each string being merged from a library. [#354]
 
 ### Bug Fixes
 
diff --git a/lib/fastlane/plugin/wpmreleasetoolkit/actions/android/an_localize_libs_action.rb b/lib/fastlane/plugin/wpmreleasetoolkit/actions/android/an_localize_libs_action.rb
index 8c82c36f3..db90162dc 100644
--- a/lib/fastlane/plugin/wpmreleasetoolkit/actions/android/an_localize_libs_action.rb
+++ b/lib/fastlane/plugin/wpmreleasetoolkit/actions/android/an_localize_libs_action.rb
@@ -33,11 +33,12 @@ def self.details
 
       def self.available_options
         libs_hash_description = <<~KEYS
-          - `:library`: The library display name
-          - `:strings_path`: The path to the `strings.xml` file of the library
-          - `:exclusions`: An optional `Array` of string keys to exclude from merging
+          - `:library`: The library display name.
+          - `:strings_path`: The path to the `strings.xml` file of the library.
+          - `:exclusions`: An optional `Array` of string keys to exclude from merging.
           - `:source_id`: An optional `String` which will be added as the `a8c-src-lib` XML attribute
             to strings coming from this library, to help identify their source in the merged file.
+          - `:add_ignore_attr`: If set to true, will add `tools:ignore="UnusedResources"` to merged strings.
         KEYS
         [
           FastlaneCore::ConfigItem.new(key: :app_strings_path,
diff --git a/lib/fastlane/plugin/wpmreleasetoolkit/helper/android/android_localize_helper.rb b/lib/fastlane/plugin/wpmreleasetoolkit/helper/android/android_localize_helper.rb
index 02487f3b8..52e914c11 100644
--- a/lib/fastlane/plugin/wpmreleasetoolkit/helper/android/android_localize_helper.rb
+++ b/lib/fastlane/plugin/wpmreleasetoolkit/helper/android/android_localize_helper.rb
@@ -33,11 +33,20 @@ def self.skip_string_by_exclusion_list(library, string_name)
           end
         end
 
+        # Adds the appropriate XML attributes to an XML `<string>` node according to library configuration
+        def self.add_xml_attributes!(string_node, library)
+          if library[:add_ignore_attr] == true
+            existing_ignores = (string_node['tools:ignore'] || '').split(',')
+            existing_ignores.append('UnusedResources') unless existing_ignores.include?('UnusedResources')
+            string_node['tools:ignore'] = existing_ignores.join(',')
+          end
+          string_node[LIB_SOURCE_XML_ATTR] = library[:source_id] unless library[:source_id].nil?
+        end
+
         # Merge string_line into main_string
         def self.merge_string(main_strings, library, string_line)
           string_name = string_line.attr('name')
           string_content = string_line.content
-          lib_src_id = library[:source_id]
 
           # Skip strings in the exclusions list
           return :skipped if skip_string_by_exclusion_list(library, string_name)
@@ -61,14 +70,14 @@ def self.merge_string(main_strings, library, string_line)
               else
                 # It has the tools:ignore flag, so update the content without touching the other attributes
                 this_string.content = string_content
-                this_string[LIB_SOURCE_XML_ATTR] = lib_src_id unless lib_src_id.nil?
+                add_xml_attributes!(this_string, library)
                 return result
               end
             end
           end
 
           # String not found, or removed because needing update and not in the exclusion list: add to the main file
-          string_line[LIB_SOURCE_XML_ATTR] = lib_src_id unless lib_src_id.nil?
+          add_xml_attributes!(string_line, library)
           main_strings.xpath('//string').last().add_next_sibling("\n#{' ' * 4}#{string_line.to_xml().strip}")
           return result
         end
@@ -103,8 +112,14 @@ def self.verify_string(main_strings, library, string_line)
         # @param [Hash] library Hash describing the library to merge. The Hash should contain the following keys:
         #                       - `:library`: The human readable name of the library, used to display in console messages
         #                       - `:strings_path`: The path to the strings.xml file of the library to merge into the main one
-        #                       - `:exclusions`: An array of strings keys to exclude during merge. Any of those keys from the library's `strings.xml` will be skipped and won't be merged into the main one.
+        #                       - `:exclusions`: An array of strings keys to exclude during merge. Any of those keys from the
+        #                         library's `strings.xml` will be skipped and won't be merged into the main one.
+        #                       - `:source_id`: An optional `String` which will be added as the `a8c-src-lib` XML attribute
+        #                         to strings coming from this library, to help identify their source in the merged file.
+        #                       - `:add_ignore_attr`: If set to `true`, will add `tools:ignore="UnusedResources"` to merged strings.
+        #
         # @return [Boolean] True if at least one string from the library has been added to (or has updated) the main strings file.
+        #
         def self.merge_lib(main, library)
           UI.message("Merging #{library[:library]} strings into #{main}")
           main_strings = File.open(main) { |f| Nokogiri::XML(f, nil, Encoding::UTF_8.to_s) }
diff --git a/spec/an_localize_libs_action_spec.rb b/spec/an_localize_libs_action_spec.rb
index 4316fec95..25f4b26d2 100644
--- a/spec/an_localize_libs_action_spec.rb
+++ b/spec/an_localize_libs_action_spec.rb
@@ -1,48 +1,223 @@
 require 'spec_helper'
 
 describe Fastlane::Actions::AnLocalizeLibsAction do
-  # This test is more of a way of ensuring `run_described_fastlane_action` handles array of hashes properly than a comprehensive test for the `an_localize_libs_action` action.
-  #
-  # Please consider expanding this test if you'll find yourself working on its action.
-  it 'merges the strings from the given array into the given main strings file' do
-    in_tmp_dir do |tmp_dir|
-      app_strings_path = File.join(tmp_dir, 'app.xml')
-      File.write(app_strings_path, android_xml_with_content('<string name="a_string">test from app</string>'))
-
-      lib1_strings_path = File.join(tmp_dir, 'lib1.xml')
-      File.write(lib1_strings_path, android_xml_with_content('<string name="a_lib1_string">test from lib 1</string>'))
-
-      lib2_strings_path = File.join(tmp_dir, 'lib2.xml')
-      File.write(lib2_strings_path, android_xml_with_content('<string name="a_lib2_string">test from lib 2</string>'))
-
-      run_described_fastlane_action(
-        app_strings_path: app_strings_path,
-        libs_strings_path: [
-          { library: 'lib_1', strings_path: lib1_strings_path, exclusions: [] },
-          { library: 'lib_2', strings_path: lib2_strings_path, exclusions: [] },
-        ]
-      )
-
-      expected = <<~XML
-        <string name="a_string">test from app</string>
-        <string name="a_lib1_string">test from lib 1</string>
-        <string name="a_lib2_string">test from lib 2</string>
-      XML
-      expect(File.read(app_strings_path)).to eq(android_xml_with_content(expected))
-    end
+  def android_xml_with_lines(lines)
+    # I couldn't find a way to interpolate a multiline string preserving its indentation in the heredoc below, so I hacked the following transformation of the input that adds the desired indentation to all lines.
+    #
+    # The desired indentation is 4 spaces to stay aligned with the production code applies when merging the XMLs.
+    indented_content = lines.map { |l| "    #{l.chomp}" }.join("\n")
+
+    return <<~XML
+      <?xml version="1.0" encoding="UTF-8"?>
+      <resources xmlns:tools="http://schemas.android.com/tools">
+      #{indented_content}
+      </resources>
+    XML
   end
-end
 
-def android_xml_with_content(content)
-  # I couldn't find a way to interpolate a multiline string preserving its indentation in the heredoc below, so I hacked the following transformation of the input that adds the desired indentation to all lines.
-  #
-  # The desired indentation is 4 spaces to stay aligned with the production code applies when merging the XMLs.
-  indented_content = content.chomp.lines.map { |l| "    #{l}" }.join
-
-  return <<~XML
-    <?xml version="1.0" encoding="UTF-8"?>
-    <resources xmlns:tools="http://schemas.android.com/tools">
-    #{indented_content}
-    </resources>
-  XML
+  def write_android_xml(path, lines)
+    File.write(path, android_xml_with_lines(lines))
+  end
+
+  describe 'merges the strings from the given array into the given main strings file' do
+    it 'handles simple XMLs with no duplicates nor attributes' do
+      in_tmp_dir do |tmp_dir|
+        app_strings_path = File.join(tmp_dir, 'app.xml')
+        File.write(app_strings_path, android_xml_with_lines(['<string name="a_string">test from app</string>']))
+
+        lib1_strings_path = File.join(tmp_dir, 'lib1.xml')
+        File.write(lib1_strings_path, android_xml_with_lines(['<string name="a_lib1_string">test from lib 1</string>']))
+
+        lib2_strings_path = File.join(tmp_dir, 'lib2.xml')
+        File.write(lib2_strings_path, android_xml_with_lines(['<string name="a_lib2_string">test from lib 2</string>']))
+
+        run_described_fastlane_action(
+          app_strings_path: app_strings_path,
+          libs_strings_path: [
+            { library: 'lib_1', strings_path: lib1_strings_path, exclusions: [] },
+            { library: 'lib_2', strings_path: lib2_strings_path, exclusions: [] },
+          ]
+        )
+
+        expected = [
+          '<string name="a_string">test from app</string>',
+          '<string name="a_lib1_string">test from lib 1</string>',
+          '<string name="a_lib2_string">test from lib 2</string>',
+        ]
+        expect(File.read(app_strings_path)).to eq(android_xml_with_lines(expected))
+      end
+    end
+
+    it 'keeps app value if content_override is used' do
+      in_tmp_dir do |tmp_dir|
+        app_strings_path = File.join(tmp_dir, 'app.xml')
+        app_xml_lines = [
+          '<string name="override-true" content_override="true">from app override-true</string>',
+          '<string name="override-false" content_override="false">from app override-false</string>',
+          '<string name="override-missing">from app override-missing</string>',
+        ]
+        File.write(app_strings_path, android_xml_with_lines(app_xml_lines))
+
+        lib_strings_path = File.join(tmp_dir, 'lib.xml')
+        lib_xml_lines = [
+          '<string name="override-true">from lib override-true</string>',
+          '<string name="override-false">from lib override-false</string>',
+          '<string name="override-missing">from lib override-missing</string>',
+        ]
+        File.write(lib_strings_path, android_xml_with_lines(lib_xml_lines))
+
+        run_described_fastlane_action(
+          app_strings_path: app_strings_path,
+          libs_strings_path: [
+            { library: 'lib', strings_path: lib_strings_path, exclusions: [] },
+          ]
+        )
+
+        expected = [
+          '<string name="override-true" content_override="true">from app override-true</string>',
+          '', '', # FIXME: Current implementation adds empty lines; we should get rid of those at some point
+          '<string name="override-false">from lib override-false</string>',
+          '<string name="override-missing">from lib override-missing</string>',
+        ]
+        expect(File.read(app_strings_path)).to eq(android_xml_with_lines(expected))
+      end
+    end
+
+    it 'adds a8c-lib-src attribute if provided' do
+      in_tmp_dir do |tmp_dir|
+        app_strings_path = File.join(tmp_dir, 'app.xml')
+        app_xml_lines = [
+          '<string name="override-true" content_override="true">from app override-true</string>',
+          '<string name="override-missing">from app override-missing</string>',
+        ]
+        File.write(app_strings_path, android_xml_with_lines(app_xml_lines))
+
+        lib1_strings_path = File.join(tmp_dir, 'lib1.xml')
+        lib1_xml_lines = [
+          '<string name="override-true">from lib1 override-true</string>',
+          '<string name="override-missing">from lib1 override-missing</string>',
+          '<string name="lib1-key">Key only present in lib1</string>',
+        ]
+        File.write(lib1_strings_path, android_xml_with_lines(lib1_xml_lines))
+
+        lib2_strings_path = File.join(tmp_dir, 'lib2.xml')
+        lib2_xml_lines = [
+          '<string name="override-true">from lib2 override-true</string>',
+          '<string name="override-missing">from lib2 override-missing</string>',
+          '<string name="lib2-key">Key only present in lib2</string>',
+        ]
+        File.write(lib2_strings_path, android_xml_with_lines(lib2_xml_lines))
+
+        run_described_fastlane_action(
+          app_strings_path: app_strings_path,
+          libs_strings_path: [
+            { library: 'lib1', strings_path: lib1_strings_path, source_id: 'lib1-id' },
+            { library: 'lib2', strings_path: lib2_strings_path, source_id: 'lib2-id' },
+          ]
+        )
+
+        expected = [
+          '<string name="override-true" content_override="true">from app override-true</string>',
+          '', # FIXME: Current implementation adds empty lines; we should get rid of those at some point
+          '<string name="lib1-key" a8c-src-lib="lib1-id">Key only present in lib1</string>',
+          '<string name="override-missing" a8c-src-lib="lib2-id">from lib2 override-missing</string>',
+          '<string name="lib2-key" a8c-src-lib="lib2-id">Key only present in lib2</string>',
+          '', # FIXME: Current implementation adds empty lines; we should get rid of those at some point
+        ]
+        expect(File.read(app_strings_path)).to eq(android_xml_with_lines(expected))
+      end
+    end
+
+    it 'adds tools:ignore attribute when requested' do
+      in_tmp_dir do |tmp_dir|
+        app_strings_path = File.join(tmp_dir, 'app.xml')
+        app_xml_lines = [
+          '<string name="override-true" content_override="true">from app, override true</string>',
+          '<string name="ignore-unused" tools:ignore="UnusedResources">from app, tools:ignore="UnusedResources"</string>',
+          '<string name="ignore-x-unused-y" tools:ignore="X,UnusedResources,Y">from app, tools:ignore mix</string>',
+          '<string name="ignore-x-y" tools:ignore="X,Y">from app, tools:ignore mix</string>',
+        ]
+        File.write(app_strings_path, android_xml_with_lines(app_xml_lines))
+
+        lib1_strings_path = File.join(tmp_dir, 'lib1.xml')
+        lib1_xml_lines = [
+          '<string name="override-true">from lib1, override true</string>',
+          '<string name="lib1-key">Key only present in lib1, no extra attribute</string>',
+          '<string name="lib1-ignore-unused" tools:ignore="UnusedResources">Key only present in lib1, with tools:ignore attribute</string>',
+          '<string name="lib1-ignore-x-y" tools:ignore="X,Y">Key only present in lib1, with tools:ignore attribute x,y</string>',
+          '<string name="lib1-ignore-x-unused-y" tools:ignore="X,UnusedResources,Y">Key only present in lib1, with tools:ignore attribute x,y</string>',
+        ]
+        File.write(lib1_strings_path, android_xml_with_lines(lib1_xml_lines))
+
+        lib2_strings_path = File.join(tmp_dir, 'lib2.xml')
+        lib2_xml_lines = [
+          '<string name="override-true">from lib2, override true</string>',
+          '<string name="lib2-key">Key only present in lib2, no extra attribute</string>',
+          '<string name="lib2-ignore-unused" tools:ignore="UnusedResources">Key only present in lib2, with tools:ignore attribute</string>',
+          '<string name="lib2-ignore-x-y" tools:ignore="X,Y">Key only present in lib2, with tools:ignore attribute x,y</string>',
+          '<string name="lib2-ignore-x-unused-y" tools:ignore="X,UnusedResources,Y">Key only present in lib2, with tools:ignore attribute x,y</string>',
+        ]
+        File.write(lib2_strings_path, android_xml_with_lines(lib2_xml_lines))
+
+        run_described_fastlane_action(
+          app_strings_path: app_strings_path,
+          libs_strings_path: [
+            { library: 'lib1', strings_path: lib1_strings_path, source_id: 'lib1', add_ignore_attr: true },
+            { library: 'lib2', strings_path: lib2_strings_path, source_id: 'lib2' },
+          ]
+        )
+
+        expected = [
+          '<string name="override-true" content_override="true">from app, override true</string>',
+          '<string name="ignore-unused" tools:ignore="UnusedResources">from app, tools:ignore="UnusedResources"</string>',
+          '<string name="ignore-x-unused-y" tools:ignore="X,UnusedResources,Y">from app, tools:ignore mix</string>',
+          '<string name="ignore-x-y" tools:ignore="X,Y">from app, tools:ignore mix</string>',
+          '<string name="lib1-key" tools:ignore="UnusedResources" a8c-src-lib="lib1">Key only present in lib1, no extra attribute</string>',
+          '<string name="lib1-ignore-unused" tools:ignore="UnusedResources" a8c-src-lib="lib1">Key only present in lib1, with tools:ignore attribute</string>',
+          '<string name="lib1-ignore-x-y" tools:ignore="X,Y,UnusedResources" a8c-src-lib="lib1">Key only present in lib1, with tools:ignore attribute x,y</string>',
+          '<string name="lib1-ignore-x-unused-y" tools:ignore="X,UnusedResources,Y" a8c-src-lib="lib1">Key only present in lib1, with tools:ignore attribute x,y</string>',
+          '<string name="lib2-key" a8c-src-lib="lib2">Key only present in lib2, no extra attribute</string>',
+          '<string name="lib2-ignore-unused" tools:ignore="UnusedResources" a8c-src-lib="lib2">Key only present in lib2, with tools:ignore attribute</string>',
+          '<string name="lib2-ignore-x-y" tools:ignore="X,Y" a8c-src-lib="lib2">Key only present in lib2, with tools:ignore attribute x,y</string>',
+          '<string name="lib2-ignore-x-unused-y" tools:ignore="X,UnusedResources,Y" a8c-src-lib="lib2">Key only present in lib2, with tools:ignore attribute x,y</string>',
+        ]
+        expect(File.read(app_strings_path)).to eq(android_xml_with_lines(expected))
+      end
+    end
+
+    it 'handles exclusions list per library' do
+      in_tmp_dir do |tmp_dir|
+        app_strings_path = File.join(tmp_dir, 'app.xml')
+        app_xml_lines = [
+          '<string name="override-true" content_override="true">from app override-true</string>',
+          '<string name="override-false" content_override="false">from app override-false</string>',
+          '<string name="override-missing">from app override-missing</string>',
+        ]
+        File.write(app_strings_path, android_xml_with_lines(app_xml_lines))
+
+        lib_strings_path = File.join(tmp_dir, 'lib.xml')
+        lib_xml_lines = [
+          '<string name="override-true">from lib override-true</string>',
+          '<string name="override-false">from lib override-false</string>',
+          '<string name="override-missing">from lib override-missing</string>',
+        ]
+        File.write(lib_strings_path, android_xml_with_lines(lib_xml_lines))
+
+        run_described_fastlane_action(
+          app_strings_path: app_strings_path,
+          libs_strings_path: [
+            { library: 'lib', strings_path: lib_strings_path, exclusions: ['override-missing'] },
+          ]
+        )
+
+        expected = [
+          '<string name="override-true" content_override="true">from app override-true</string>',
+          '', # FIXME: Current implementation adds empty lines; we should get rid of those at some point
+          '<string name="override-missing">from app override-missing</string>',
+          '<string name="override-false">from lib override-false</string>',
+        ]
+        expect(File.read(app_strings_path)).to eq(android_xml_with_lines(expected))
+      end
+    end
+  end
 end