diff --git a/icu4c/source/common/locdispnames.cpp b/icu4c/source/common/locdispnames.cpp
index 70470a862912..5f725e09ae89 100644
--- a/icu4c/source/common/locdispnames.cpp
+++ b/icu4c/source/common/locdispnames.cpp
@@ -835,7 +835,10 @@ uloc_getDisplayKeywordValue(   const char* locale,
     }
 
     /* get the keyword value */
-    CharString keywordValue = ulocimp_getKeywordValue(locale, keyword, *status);
+    CharString keywordValue;
+    if (keyword != nullptr && *keyword != '\0') {
+        keywordValue = ulocimp_getKeywordValue(locale, keyword, *status);
+    }
 
     /* 
      * if the keyword is equal to currency .. then to get the display name 
diff --git a/icu4c/source/common/locid.cpp b/icu4c/source/common/locid.cpp
index df6211947027..d608ba8a2ed4 100644
--- a/icu4c/source/common/locid.cpp
+++ b/icu4c/source/common/locid.cpp
@@ -2597,13 +2597,7 @@ Locale::getKeywordValue(StringPiece keywordName, ByteSink& sink, UErrorCode& sta
         return;
     }
 
-    // TODO: Remove the need for a const char* to a NUL terminated buffer.
-    const CharString keywordName_nul(keywordName, status);
-    if (U_FAILURE(status)) {
-        return;
-    }
-
-    ulocimp_getKeywordValue(fullName, keywordName_nul.data(), sink, status);
+    ulocimp_getKeywordValue(fullName, keywordName, sink, status);
 }
 
 void
diff --git a/icu4c/source/common/loclikely.cpp b/icu4c/source/common/loclikely.cpp
index e7188be3667b..1e6538134a6a 100644
--- a/icu4c/source/common/loclikely.cpp
+++ b/icu4c/source/common/loclikely.cpp
@@ -19,6 +19,7 @@
 *   that then do not depend on resource bundle code and likely-subtags data.
 */
 
+#include <string_view>
 #include <utility>
 
 #include "unicode/bytestream.h"
@@ -388,7 +389,7 @@ U_NAMESPACE_END
 
 namespace {
 icu::CharString
-GetRegionFromKey(const char* localeID, const char* key, UErrorCode& status) {
+GetRegionFromKey(const char* localeID, std::string_view key, UErrorCode& status) {
     icu::CharString result;
 
     // First check for keyword value
diff --git a/icu4c/source/common/uloc.cpp b/icu4c/source/common/uloc.cpp
index c2b7bbfd6af0..a8621a8912c2 100644
--- a/icu4c/source/common/uloc.cpp
+++ b/icu4c/source/common/uloc.cpp
@@ -31,6 +31,7 @@
 */
 
 #include <optional>
+#include <string_view>
 
 #include "unicode/bytestream.h"
 #include "unicode/errorcode.h"
@@ -551,17 +552,17 @@ namespace {
  * @param status return status (keyword too long)
  * @return the keyword name
  */
-CharString locale_canonKeywordName(const char* keywordName, UErrorCode& status)
+CharString locale_canonKeywordName(std::string_view keywordName, UErrorCode& status)
 {
   if (U_FAILURE(status)) { return {}; }
   CharString result;
 
-  for (; *keywordName != 0; keywordName++) {
-    if (!UPRV_ISALPHANUM(*keywordName)) {
+  for (char c : keywordName) {
+    if (!UPRV_ISALPHANUM(c)) {
       status = U_ILLEGAL_ARGUMENT_ERROR; /* malformed keyword name */
       return {};
     }
-    result.append(uprv_tolower(*keywordName), status);
+    result.append(uprv_tolower(c), status);
   }
   if (result.isEmpty()) {
     status = U_ILLEGAL_ARGUMENT_ERROR; /* empty keyword name */
@@ -733,6 +734,11 @@ uloc_getKeywordValue(const char* localeID,
                      char* buffer, int32_t bufferCapacity,
                      UErrorCode* status)
 {
+    if (U_FAILURE(*status)) { return 0; }
+    if (keywordName == nullptr || *keywordName == '\0') {
+        *status = U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
     return ByteSinkUtil::viaByteSinkToTerminatedChars(
         buffer, bufferCapacity,
         [&](ByteSink& sink, UErrorCode& status) {
@@ -743,7 +749,7 @@ uloc_getKeywordValue(const char* localeID,
 
 U_EXPORT CharString
 ulocimp_getKeywordValue(const char* localeID,
-                        const char* keywordName,
+                        std::string_view keywordName,
                         UErrorCode& status)
 {
     return ByteSinkUtil::viaByteSinkToCharString(
@@ -755,13 +761,13 @@ ulocimp_getKeywordValue(const char* localeID,
 
 U_EXPORT void
 ulocimp_getKeywordValue(const char* localeID,
-                        const char* keywordName,
+                        std::string_view keywordName,
                         icu::ByteSink& sink,
                         UErrorCode& status)
 {
     if (U_FAILURE(status)) { return; }
 
-    if (localeID == nullptr || keywordName == nullptr || keywordName[0] == 0) {
+    if (localeID == nullptr || keywordName.empty()) {
         status = U_ILLEGAL_ARGUMENT_ERROR;
         return;
     }
diff --git a/icu4c/source/common/ulocimp.h b/icu4c/source/common/ulocimp.h
index ff3910ac8f35..5eab0812cf58 100644
--- a/icu4c/source/common/ulocimp.h
+++ b/icu4c/source/common/ulocimp.h
@@ -11,6 +11,7 @@
 #define ULOCIMP_H
 
 #include <cstddef>
+#include <string_view>
 
 #include "unicode/bytestream.h"
 #include "unicode/uloc.h"
@@ -95,12 +96,12 @@ ulocimp_canonicalize(const char* localeID,
 
 U_EXPORT icu::CharString
 ulocimp_getKeywordValue(const char* localeID,
-                        const char* keywordName,
+                        std::string_view keywordName,
                         UErrorCode& status);
 
 U_EXPORT void
 ulocimp_getKeywordValue(const char* localeID,
-                        const char* keywordName,
+                        std::string_view keywordName,
                         icu::ByteSink& sink,
                         UErrorCode& status);
 
diff --git a/icu4c/source/common/uresbund.cpp b/icu4c/source/common/uresbund.cpp
index 59b08688319c..cfe2f4a4d20f 100644
--- a/icu4c/source/common/uresbund.cpp
+++ b/icu4c/source/common/uresbund.cpp
@@ -3074,9 +3074,12 @@ ures_getFunctionalEquivalent(char *result, int32_t resultCapacity,
     UErrorCode subStatus = U_ZERO_ERROR;
     int32_t length = 0;
     if(U_FAILURE(*status)) return 0;
-    CharString kwVal = ulocimp_getKeywordValue(locid, keyword, subStatus);
-    if(kwVal == DEFAULT_TAG) {
-        kwVal.clear();
+    CharString kwVal;
+    if (keyword != nullptr && *keyword != '\0') {
+        kwVal = ulocimp_getKeywordValue(locid, keyword, subStatus);
+        if (kwVal == DEFAULT_TAG) {
+            kwVal.clear();
+        }
     }
     CharString base = ulocimp_getBaseName(locid, subStatus);
 #if defined(URES_TREE_DEBUG)