diff --git a/Libraries/LibJS/Runtime/DatePrototype.cpp b/Libraries/LibJS/Runtime/DatePrototype.cpp
index a6ffb51d75f..e47b51d3721 100644
--- a/Libraries/LibJS/Runtime/DatePrototype.cpp
+++ b/Libraries/LibJS/Runtime/DatePrototype.cpp
@@ -1134,7 +1134,7 @@ ByteString time_zone_string(double time)
 
     // Most implementations seem to prefer the long-form display name of the time zone. Not super important, but we may as well match that behavior.
     if (auto name = Unicode::time_zone_display_name(Unicode::default_locale(), tz_name, in_dst, time); name.has_value())
-        tz_name = name.release_value();
+        tz_name = name->to_utf8_but_should_be_ported_to_utf16();
 
     // 10. Return the string-concatenation of offsetString and tzName.
     return ByteString::formatted("{} ({})", offset_string, tz_name);
diff --git a/Libraries/LibJS/Runtime/Intl/DisplayNamesPrototype.cpp b/Libraries/LibJS/Runtime/Intl/DisplayNamesPrototype.cpp
index dcbb701ca87..64b888e4201 100644
--- a/Libraries/LibJS/Runtime/Intl/DisplayNamesPrototype.cpp
+++ b/Libraries/LibJS/Runtime/Intl/DisplayNamesPrototype.cpp
@@ -83,7 +83,7 @@ JS_DEFINE_NATIVE_FUNCTION(DisplayNamesPrototype::of)
 
     // 5. Let fields be displayNames.[[Fields]].
     // 6. If fields has a field [[<code>]], return fields.[[<code>]].
-    Optional<String> result;
+    Optional<Utf16String> result;
 
     switch (display_names->type()) {
     case DisplayNames::Type::Language:
diff --git a/Libraries/LibUnicode/DisplayNames.cpp b/Libraries/LibUnicode/DisplayNames.cpp
index f2ad8442351..14574c14a97 100644
--- a/Libraries/LibUnicode/DisplayNames.cpp
+++ b/Libraries/LibUnicode/DisplayNames.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ * Copyright (c) 2024-2025, Tim Flynn <trflynn89@ladybird.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -37,7 +37,7 @@ StringView language_display_to_string(LanguageDisplay language_display)
     }
 }
 
-Optional<String> language_display_name(StringView locale, StringView language, LanguageDisplay display)
+Optional<Utf16String> language_display_name(StringView locale, StringView language, LanguageDisplay display)
 {
     auto locale_data = LocaleData::for_locale(locale);
     if (!locale_data.has_value())
@@ -54,10 +54,10 @@ Optional<String> language_display_name(StringView locale, StringView language, L
     icu::UnicodeString result;
     display_names.localeDisplayName(language_data->locale().getName(), result);
 
-    return icu_string_to_string(result);
+    return icu_string_to_utf16_string(result);
 }
 
-Optional<String> region_display_name(StringView locale, StringView region)
+Optional<Utf16String> region_display_name(StringView locale, StringView region)
 {
     UErrorCode status = U_ZERO_ERROR;
 
@@ -72,10 +72,10 @@ Optional<String> region_display_name(StringView locale, StringView region)
     icu::UnicodeString result;
     locale_data->standard_display_names().regionDisplayName(icu_region.getCountry(), result);
 
-    return icu_string_to_string(result);
+    return icu_string_to_utf16_string(result);
 }
 
-Optional<String> script_display_name(StringView locale, StringView script)
+Optional<Utf16String> script_display_name(StringView locale, StringView script)
 {
     UErrorCode status = U_ZERO_ERROR;
 
@@ -90,10 +90,10 @@ Optional<String> script_display_name(StringView locale, StringView script)
     icu::UnicodeString result;
     locale_data->standard_display_names().scriptDisplayName(icu_script.getScript(), result);
 
-    return icu_string_to_string(result);
+    return icu_string_to_utf16_string(result);
 }
 
-Optional<String> calendar_display_name(StringView locale, StringView calendar)
+Optional<Utf16String> calendar_display_name(StringView locale, StringView calendar)
 {
     auto locale_data = LocaleData::for_locale(locale);
     if (!locale_data.has_value())
@@ -109,7 +109,7 @@ Optional<String> calendar_display_name(StringView locale, StringView calendar)
     icu::UnicodeString result;
     locale_data->standard_display_names().keyValueDisplayName("calendar", ByteString(calendar).characters(), result);
 
-    return icu_string_to_string(result);
+    return icu_string_to_utf16_string(result);
 }
 
 static constexpr UDateTimePatternField icu_date_time_field(StringView field)
@@ -155,7 +155,7 @@ static constexpr UDateTimePGDisplayWidth icu_date_time_style(Style style)
     VERIFY_NOT_REACHED();
 }
 
-Optional<String> date_time_field_display_name(StringView locale, StringView field, Style style)
+Optional<Utf16String> date_time_field_display_name(StringView locale, StringView field, Style style)
 {
     auto locale_data = LocaleData::for_locale(locale);
     if (!locale_data.has_value())
@@ -167,10 +167,10 @@ Optional<String> date_time_field_display_name(StringView locale, StringView fiel
     icu::UnicodeString result;
     result = locale_data->date_time_pattern_generator().getFieldDisplayName(icu_field, icu_style);
 
-    return icu_string_to_string(result);
+    return icu_string_to_utf16_string(result);
 }
 
-Optional<String> time_zone_display_name(StringView locale, StringView time_zone_identifier, TimeZoneOffset::InDST in_dst, double time)
+Optional<Utf16String> time_zone_display_name(StringView locale, StringView time_zone_identifier, TimeZoneOffset::InDST in_dst, double time)
 {
     auto locale_data = LocaleData::for_locale(locale);
     if (!locale_data.has_value())
@@ -183,7 +183,7 @@ Optional<String> time_zone_display_name(StringView locale, StringView time_zone_
     if (static_cast<bool>(time_zone_name.isBogus()))
         return {};
 
-    return icu_string_to_string(time_zone_name);
+    return icu_string_to_utf16_string(time_zone_name);
 }
 
 static constexpr Array<UChar, 4> icu_currency_code(StringView currency)
@@ -212,7 +212,7 @@ static constexpr UCurrNameStyle icu_currency_style(Style style)
     VERIFY_NOT_REACHED();
 }
 
-Optional<String> currency_display_name(StringView locale, StringView currency, Style style)
+Optional<Utf16String> currency_display_name(StringView locale, StringView currency, Style style)
 {
     UErrorCode status = U_ZERO_ERROR;
 
@@ -230,10 +230,10 @@ Optional<String> currency_display_name(StringView locale, StringView currency, S
     if ((status == U_USING_DEFAULT_WARNING) && (result == icu_currency.data()))
         return {};
 
-    return icu_string_to_string(result, length);
+    return icu_string_to_utf16_string(result, length);
 }
 
-Optional<String> currency_numeric_display_name(StringView locale, StringView currency)
+Optional<Utf16String> currency_numeric_display_name(StringView locale, StringView currency)
 {
     UErrorCode status = U_ZERO_ERROR;
 
@@ -251,7 +251,7 @@ Optional<String> currency_numeric_display_name(StringView locale, StringView cur
     if ((status == U_USING_DEFAULT_WARNING) && (result == icu_currency.data()))
         return {};
 
-    return icu_string_to_string(result, length);
+    return icu_string_to_utf16_string(result, length);
 }
 
 }
diff --git a/Libraries/LibUnicode/DisplayNames.h b/Libraries/LibUnicode/DisplayNames.h
index 615cd260137..bd9ad1e8509 100644
--- a/Libraries/LibUnicode/DisplayNames.h
+++ b/Libraries/LibUnicode/DisplayNames.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ * Copyright (c) 2024-2025, Tim Flynn <trflynn89@ladybird.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -7,8 +7,8 @@
 #pragma once
 
 #include <AK/Optional.h>
-#include <AK/String.h>
 #include <AK/StringView.h>
+#include <AK/Utf16String.h>
 #include <LibUnicode/Locale.h>
 #include <LibUnicode/TimeZone.h>
 
@@ -22,13 +22,13 @@ enum class LanguageDisplay {
 LanguageDisplay language_display_from_string(StringView language_display);
 StringView language_display_to_string(LanguageDisplay language_display);
 
-Optional<String> language_display_name(StringView locale, StringView language, LanguageDisplay);
-Optional<String> region_display_name(StringView locale, StringView region);
-Optional<String> script_display_name(StringView locale, StringView script);
-Optional<String> calendar_display_name(StringView locale, StringView calendar);
-Optional<String> date_time_field_display_name(StringView locale, StringView field, Style);
-Optional<String> time_zone_display_name(StringView locale, StringView time_zone_identifier, TimeZoneOffset::InDST, double time);
-Optional<String> currency_display_name(StringView locale, StringView currency, Style);
-Optional<String> currency_numeric_display_name(StringView locale, StringView currency);
+Optional<Utf16String> language_display_name(StringView locale, StringView language, LanguageDisplay);
+Optional<Utf16String> region_display_name(StringView locale, StringView region);
+Optional<Utf16String> script_display_name(StringView locale, StringView script);
+Optional<Utf16String> calendar_display_name(StringView locale, StringView calendar);
+Optional<Utf16String> date_time_field_display_name(StringView locale, StringView field, Style);
+Optional<Utf16String> time_zone_display_name(StringView locale, StringView time_zone_identifier, TimeZoneOffset::InDST, double time);
+Optional<Utf16String> currency_display_name(StringView locale, StringView currency, Style);
+Optional<Utf16String> currency_numeric_display_name(StringView locale, StringView currency);
 
 }
diff --git a/Libraries/LibUnicode/ICU.cpp b/Libraries/LibUnicode/ICU.cpp
index ec1ce4a3151..9a4b9c0f7af 100644
--- a/Libraries/LibUnicode/ICU.cpp
+++ b/Libraries/LibUnicode/ICU.cpp
@@ -164,7 +164,12 @@ String icu_string_to_string(UChar const* string, i32 length)
 
 Utf16String icu_string_to_utf16_string(icu::UnicodeString const& string)
 {
-    return Utf16String::from_utf16_without_validation({ string.getBuffer(), static_cast<size_t>(string.length()) });
+    return icu_string_to_utf16_string(string.getBuffer(), string.length());
+}
+
+Utf16String icu_string_to_utf16_string(UChar const* string, i32 length)
+{
+    return Utf16String::from_utf16_without_validation({ string, static_cast<size_t>(length) });
 }
 
 UCharIterator icu_string_iterator(Utf16View const& string)
diff --git a/Libraries/LibUnicode/ICU.h b/Libraries/LibUnicode/ICU.h
index fa9dc3a68df..26bea7d1933 100644
--- a/Libraries/LibUnicode/ICU.h
+++ b/Libraries/LibUnicode/ICU.h
@@ -105,6 +105,7 @@ String icu_string_to_string(icu::UnicodeString const& string);
 String icu_string_to_string(UChar const*, i32 length);
 
 Utf16String icu_string_to_utf16_string(icu::UnicodeString const& string);
+Utf16String icu_string_to_utf16_string(UChar const*, i32 length);
 
 UCharIterator icu_string_iterator(Utf16View const&);
 
diff --git a/Tests/LibUnicode/TestDisplayNames.cpp b/Tests/LibUnicode/TestDisplayNames.cpp
index 1c8aeed9c8a..a1495df3ca4 100644
--- a/Tests/LibUnicode/TestDisplayNames.cpp
+++ b/Tests/LibUnicode/TestDisplayNames.cpp
@@ -13,21 +13,21 @@ TEST_CASE(locale_mappings_en)
 {
     auto language = Unicode::language_display_name("en"sv, "en"sv, Unicode::LanguageDisplay::Standard);
     EXPECT(language.has_value());
-    EXPECT_EQ(*language, "English"sv);
+    EXPECT_EQ(*language, u"English"sv);
 
     language = Unicode::language_display_name("en"sv, "i-definitely-don't-exist"sv, Unicode::LanguageDisplay::Standard);
     EXPECT(!language.has_value());
 
     auto territory = Unicode::region_display_name("en"sv, "US"sv);
     EXPECT(territory.has_value());
-    EXPECT_EQ(*territory, "United States"sv);
+    EXPECT_EQ(*territory, u"United States"sv);
 
     territory = Unicode::region_display_name("en"sv, "i-definitely-don't-exist"sv);
     EXPECT(!territory.has_value());
 
     auto script = Unicode::script_display_name("en"sv, "Latn"sv);
     EXPECT(script.has_value());
-    EXPECT_EQ(*script, "Latin"sv);
+    EXPECT_EQ(*script, u"Latin"sv);
 
     script = Unicode::script_display_name("en"sv, "i-definitely-don't-exist"sv);
     EXPECT(!script.has_value());
@@ -37,21 +37,21 @@ TEST_CASE(locale_mappings_fr)
 {
     auto language = Unicode::language_display_name("fr"sv, "en"sv, Unicode::LanguageDisplay::Standard);
     EXPECT(language.has_value());
-    EXPECT_EQ(*language, "anglais"sv);
+    EXPECT_EQ(*language, u"anglais"sv);
 
     language = Unicode::language_display_name("fr"sv, "i-definitely-don't-exist"sv, Unicode::LanguageDisplay::Standard);
     EXPECT(!language.has_value());
 
     auto territory = Unicode::region_display_name("fr"sv, "US"sv);
     EXPECT(territory.has_value());
-    EXPECT_EQ(*territory, "États-Unis"sv);
+    EXPECT_EQ(*territory, u"États-Unis"sv);
 
     territory = Unicode::region_display_name("fr"sv, "i-definitely-don't-exist"sv);
     EXPECT(!territory.has_value());
 
     auto script = Unicode::script_display_name("fr"sv, "Latn"sv);
     EXPECT(script.has_value());
-    EXPECT_EQ(*script, "latin"sv);
+    EXPECT_EQ(*script, u"latin"sv);
 
     script = Unicode::script_display_name("fr"sv, "i-definitely-don't-exist"sv);
     EXPECT(!script.has_value());
@@ -61,21 +61,21 @@ TEST_CASE(locale_mappings_root)
 {
     auto language = Unicode::language_display_name("und"sv, "en"sv, Unicode::LanguageDisplay::Standard);
     EXPECT(language.has_value());
-    EXPECT_EQ(*language, "en"sv);
+    EXPECT_EQ(*language, u"en"sv);
 
     language = Unicode::language_display_name("und"sv, "i-definitely-don't-exist"sv, Unicode::LanguageDisplay::Standard);
     EXPECT(!language.has_value());
 
     auto territory = Unicode::region_display_name("und"sv, "US"sv);
     EXPECT(territory.has_value());
-    EXPECT_EQ(*territory, "US"sv);
+    EXPECT_EQ(*territory, u"US"sv);
 
     territory = Unicode::region_display_name("und"sv, "i-definitely-don't-exist"sv);
     EXPECT(!territory.has_value());
 
     auto script = Unicode::script_display_name("und"sv, "Latn"sv);
     EXPECT(script.has_value());
-    EXPECT_EQ(*script, "Latn"sv);
+    EXPECT_EQ(*script, u"Latn"sv);
 
     script = Unicode::script_display_name("und"sv, "i-definitely-don't-exist"sv);
     EXPECT(!script.has_value());