diff --git a/icu4c/source/i18n/tznames_impl.cpp b/icu4c/source/i18n/tznames_impl.cpp
index ec0ef8ec40f..c315d2b5d5b 100644
--- a/icu4c/source/i18n/tznames_impl.cpp
+++ b/icu4c/source/i18n/tznames_impl.cpp
@@ -34,6 +34,7 @@
 #include "ureslocs.h"
 #include "zonemeta.h"
 #include "ucln_in.h"
+#include "uinvchar.h"
 #include "uvector.h"
 #include "olsontz.h"
 
@@ -2280,6 +2281,10 @@ TZDBTimeZoneNames::getMetaZoneNames(const UnicodeString& mzID, UErrorCode& statu
         return nullptr;
     }
     mzIDKey[mzID.length()] = 0;
+    if (!uprv_isInvariantUString(mzIDKey, mzID.length())) {
+        status = U_ILLEGAL_ARGUMENT_ERROR;
+        return nullptr;
+    }
 
     static UMutex gTZDBNamesMapLock;
     umtx_lock(&gTZDBNamesMapLock);
diff --git a/icu4c/source/test/intltest/tzfmttst.cpp b/icu4c/source/test/intltest/tzfmttst.cpp
index ddb49946234..247939a8d28 100644
--- a/icu4c/source/test/intltest/tzfmttst.cpp
+++ b/icu4c/source/test/intltest/tzfmttst.cpp
@@ -89,6 +89,7 @@ TimeZoneFormatTest::runIndexedTest( int32_t index, UBool exec, const char* &name
         TESTCASE(9, TestCentralTime);
         TESTCASE(10, TestBogusLocale);
         TESTCASE(11, Test22614GetMetaZoneNamesNotCrash);
+        TESTCASE(12, Test22615NonASCIIID);
     default: name = ""; break;
     }
 }
@@ -1316,6 +1317,52 @@ TimeZoneFormatTest::TestFormatCustomZone() {
     }
 }
 
+void
+TimeZoneFormatTest::Test22615NonASCIIID() {
+    UErrorCode status = U_ZERO_ERROR;
+    LocalPointer<TimeZoneNames> tzdb(TimeZoneNames::createTZDBInstance(Locale("en"), status));
+    // A test to ensure under the debugging build non ASCII id will not cause
+    // internal assertion error.
+    UnicodeString id(9, u'\u00C0', 8);
+    UnicodeString output;
+    tzdb->getMetaZoneDisplayName(id, UTZNM_SHORT_STANDARD, output);
+    assertTrue("getMetaZoneID of non ASCII id should return bogus string",
+               output.isBogus());
+
+    status = U_ZERO_ERROR;
+    std::unique_ptr<icu::StringEnumeration> enumeration(
+        tzdb->getAvailableMetaZoneIDs(id, status));
+    assertSuccess("getAvailableMetaZoneIDs should success", status);
+    assertEquals("getAvailableMetaZoneIDs with non ASCII id return 0 ids",
+                 0, enumeration->count(status));
+    assertSuccess("count should success", status);
+
+    output.remove();
+    tzdb->getMetaZoneID(id, 0, output);
+    assertTrue("getMetaZoneID of non ASCII id should return bogus string",
+               output.isBogus());
+
+    output.remove();
+    tzdb->getMetaZoneDisplayName(id, UTZNM_EXEMPLAR_LOCATION, output);
+    assertTrue("getMetaZoneDisplayName of non ASCII id should return bogus string",
+               output.isBogus());
+
+    output.remove();
+    tzdb->getTimeZoneDisplayName(id, UTZNM_SHORT_DAYLIGHT, output);
+    assertTrue("getTimeZoneDisplayName of non ASCII id should return bogus string",
+               output.isBogus());
+
+    output.remove();
+    tzdb->getExemplarLocationName(id, output);
+    assertTrue("getExemplarLocationName of non ASCII id should return bogus string",
+               output.isBogus());
+
+    output.remove();
+    tzdb->getDisplayName(id, UTZNM_LONG_GENERIC, 0, output);
+    assertTrue("getDisplayName of non ASCII id should return bogus string",
+               output.isBogus());
+}
+
 void
 TimeZoneFormatTest::Test22614GetMetaZoneNamesNotCrash() {
     UErrorCode status = U_ZERO_ERROR;
diff --git a/icu4c/source/test/intltest/tzfmttst.h b/icu4c/source/test/intltest/tzfmttst.h
index 1bcae2955bc..88258cf9b2b 100644
--- a/icu4c/source/test/intltest/tzfmttst.h
+++ b/icu4c/source/test/intltest/tzfmttst.h
@@ -33,6 +33,7 @@ class TimeZoneFormatTest : public IntlTest {
     void TestCentralTime();
     void TestBogusLocale();
     void Test22614GetMetaZoneNamesNotCrash();
+    void Test22615NonASCIIID();
 
     void RunTimeRoundTripTests(int32_t threadNumber);
     void RunAdoptDefaultThreadSafeTests(int32_t threadNumber);