diff --git a/src/GitParamTabExpansion.ps1 b/src/GitParamTabExpansion.ps1
index a0947e8a8..9bf32d832 100644
--- a/src/GitParamTabExpansion.ps1
+++ b/src/GitParamTabExpansion.ps1
@@ -150,8 +150,14 @@ $gitParamValues = @{
     log = @{
         decorate = 'short full no'
         'no-walk' = 'sorted unsorted'
-        pretty = 'oneline short medium full fuller email raw'
-        format = 'oneline short medium full fuller email raw'
+        pretty = {
+            param($format)
+            gitConfigKeys 'pretty' $format 'oneline short medium full fuller email raw'
+        }
+        format = {
+            param($format)
+            gitConfigKeys 'pretty' $format 'oneline short medium full fuller email raw'
+        }
         encoding = 'UTF-8'
         date = 'relative local default iso rfc short raw'
     }
@@ -189,8 +195,14 @@ $gitParamValues = @{
         strategy = 'resolve recursive octopus ours subtree'
     }
     show = @{
-        pretty = 'oneline short medium full fuller email raw'
-        format = 'oneline short medium full fuller email raw'
+        pretty = {
+            param($format)
+            gitConfigKeys 'pretty' $format 'oneline short medium full fuller email raw'
+        }
+        format = {
+            param($format)
+            gitConfigKeys 'pretty' $format 'oneline short medium full fuller email raw'
+        }
         encoding = 'utf-8'
     }
     status = @{
diff --git a/src/GitTabExpansion.ps1 b/src/GitTabExpansion.ps1
index 956eed84d..65ab7d585 100644
--- a/src/GitTabExpansion.ps1
+++ b/src/GitTabExpansion.ps1
@@ -155,6 +155,18 @@ function script:gitRemoteUniqueBranches($filter) {
         quoteStringWithSpecialChars
 }
 
+function script:gitConfigKeys($section, $filter, $defaultOptions = '') {
+    $completions = @($defaultOptions -split ' ')
+
+    git config --name-only --get-regexp ^$section\..* |
+        ForEach-Object { $completions += ($_ -replace "$section\.","") }
+
+    return $completions |
+        Where-Object { $_ -like "$filter*" } |
+        Sort-Object |
+        quoteStringWithSpecialChars
+}
+
 function script:gitTags($filter, $prefix = '') {
     git tag |
         Where-Object { $_ -like "$filter*" } |
diff --git a/test/GitParamTabExpansion.Tests.ps1 b/test/GitParamTabExpansion.Tests.ps1
index 4b3554cbc..8eaf20d41 100644
--- a/test/GitParamTabExpansion.Tests.ps1
+++ b/test/GitParamTabExpansion.Tests.ps1
@@ -44,5 +44,111 @@ Describe 'ParamsTabExpansion Tests' {
             $result -contains '--recurse-submodules=on-demand' | Should -Be $true
         }
     }
+
+    Context 'Pretty/Format TabCompletion Tests - No Custom Formats' {
+        It 'Tab completes default formats for log --pretty' {
+            $result = & $module GitTabExpansionInternal 'git log --pretty='
+            $result -contains '--pretty=oneline' | Should -Be $true
+            $result -contains '--pretty=short' | Should -Be $true
+            $result -contains '--pretty=medium' | Should -Be $true
+            $result -contains '--pretty=full' | Should -Be $true
+            $result -contains '--pretty=fuller' | Should -Be $true
+            $result -contains '--pretty=email' | Should -Be $true
+            $result -contains '--pretty=raw' | Should -Be $true
+        }
+        It 'Tab completes default formats for log --format' {
+            $result = & $module GitTabExpansionInternal 'git log --format='
+            $result -contains '--format=oneline' | Should -Be $true
+            $result -contains '--format=short' | Should -Be $true
+            $result -contains '--format=medium' | Should -Be $true
+            $result -contains '--format=full' | Should -Be $true
+            $result -contains '--format=fuller' | Should -Be $true
+            $result -contains '--format=email' | Should -Be $true
+            $result -contains '--format=raw' | Should -Be $true
+        }
+        It 'Tab completes default formats for show --pretty' {
+            $result = & $module GitTabExpansionInternal 'git show --pretty='
+            $result -contains '--pretty=oneline' | Should -Be $true
+            $result -contains '--pretty=short' | Should -Be $true
+            $result -contains '--pretty=medium' | Should -Be $true
+            $result -contains '--pretty=full' | Should -Be $true
+            $result -contains '--pretty=fuller' | Should -Be $true
+            $result -contains '--pretty=email' | Should -Be $true
+            $result -contains '--pretty=raw' | Should -Be $true
+        }
+        It 'Tab completes default formats for show --format' {
+            $result = & $module GitTabExpansionInternal 'git show --format='
+            $result -contains '--format=oneline' | Should -Be $true
+            $result -contains '--format=short' | Should -Be $true
+            $result -contains '--format=medium' | Should -Be $true
+            $result -contains '--format=full' | Should -Be $true
+            $result -contains '--format=fuller' | Should -Be $true
+            $result -contains '--format=email' | Should -Be $true
+            $result -contains '--format=raw' | Should -Be $true
+        }
+    }
+
+    Context 'Pretty/Format TabCompletion Tests - With Custom Formats' {
+        BeforeEach {
+            [System.Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSUseDeclaredVarsMoreThanAssigments', '')]
+            $repoPath = NewGitTempRepo
+
+            # Test with custom formats
+            &$gitbin config pretty.birdseye "%C(auto)%h%d %s %C(bold blue)<%aN> %C(green)(%cr)%Creset"
+            &$gitbin config pretty.test2 "%h%d %s <%aN> (%cr)"
+        }
+        AfterEach {
+            RemoveGitTempRepo $repoPath
+        }
+
+        It 'Tab completes default and custom formats for log --pretty' {
+            $result = & $module GitTabExpansionInternal 'git log --pretty='
+            $result -contains '--pretty=oneline' | Should -Be $true
+            $result -contains '--pretty=short' | Should -Be $true
+            $result -contains '--pretty=medium' | Should -Be $true
+            $result -contains '--pretty=full' | Should -Be $true
+            $result -contains '--pretty=fuller' | Should -Be $true
+            $result -contains '--pretty=email' | Should -Be $true
+            $result -contains '--pretty=raw' | Should -Be $true
+            $result -contains '--pretty=birdseye' | Should -Be $true
+            $result -contains '--pretty=test2' | Should -Be $true
+        }
+        It 'Tab completes default and custom formats for log --format' {
+            $result = & $module GitTabExpansionInternal 'git log --format='
+            $result -contains '--format=oneline' | Should -Be $true
+            $result -contains '--format=short' | Should -Be $true
+            $result -contains '--format=medium' | Should -Be $true
+            $result -contains '--format=full' | Should -Be $true
+            $result -contains '--format=fuller' | Should -Be $true
+            $result -contains '--format=email' | Should -Be $true
+            $result -contains '--format=raw' | Should -Be $true
+            $result -contains '--format=birdseye' | Should -Be $true
+            $result -contains '--format=test2' | Should -Be $true
+        }
+        It 'Tab completes default and custom formats for show --pretty' {
+            $result = & $module GitTabExpansionInternal 'git show --pretty='
+            $result -contains '--pretty=oneline' | Should -Be $true
+            $result -contains '--pretty=short' | Should -Be $true
+            $result -contains '--pretty=medium' | Should -Be $true
+            $result -contains '--pretty=full' | Should -Be $true
+            $result -contains '--pretty=fuller' | Should -Be $true
+            $result -contains '--pretty=email' | Should -Be $true
+            $result -contains '--pretty=raw' | Should -Be $true
+            $result -contains '--pretty=birdseye' | Should -Be $true
+            $result -contains '--pretty=test2' | Should -Be $true
+        }
+        It 'Tab completes default and custom formats for show --format' {
+            $result = & $module GitTabExpansionInternal 'git show --format='
+            $result -contains '--format=oneline' | Should -Be $true
+            $result -contains '--format=short' | Should -Be $true
+            $result -contains '--format=medium' | Should -Be $true
+            $result -contains '--format=full' | Should -Be $true
+            $result -contains '--format=fuller' | Should -Be $true
+            $result -contains '--format=email' | Should -Be $true
+            $result -contains '--format=raw' | Should -Be $true
+            $result -contains '--format=birdseye' | Should -Be $true
+            $result -contains '--format=test2' | Should -Be $true
+        }
+    }
 }