diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index c880d831e86..c376d3165de 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -39,6 +39,8 @@
         `Player.addListener`.
     *   Fix initial timestamp display in `PlayerControlView`
         ([#9524](https://github.com/google/ExoPlayer/issues/9254)).
+    *   Fix capitalization of languages in the track selector
+        ([#9452](https://github.com/google/ExoPlayer/issues/9452)).
 *   Extractors:
     *   MP4: Correctly handle HEVC tracks with pixel aspect ratios other than 1.
     *   TS: Correctly handle HEVC tracks with pixel aspect ratios other than 1.
diff --git a/library/common/src/main/java/com/google/android/exoplayer2/util/Util.java b/library/common/src/main/java/com/google/android/exoplayer2/util/Util.java
index e5bd28aca23..27a0d936702 100644
--- a/library/common/src/main/java/com/google/android/exoplayer2/util/Util.java
+++ b/library/common/src/main/java/com/google/android/exoplayer2/util/Util.java
@@ -2243,6 +2243,11 @@ public static String[] getSystemLanguageCodes() {
     return systemLocales;
   }
 
+  /** Returns the default {@link Locale.Category#DISPLAY DISPLAY} {@link Locale}. */
+  public static Locale getDefaultDisplayLocale() {
+    return Util.SDK_INT >= 24 ? Locale.getDefault(Locale.Category.DISPLAY) : Locale.getDefault();
+  }
+
   /**
    * Uncompresses the data in {@code input}.
    *
diff --git a/library/ui/src/main/java/com/google/android/exoplayer2/ui/DefaultTrackNameProvider.java b/library/ui/src/main/java/com/google/android/exoplayer2/ui/DefaultTrackNameProvider.java
index a3d20eadb7d..59fde6950f5 100644
--- a/library/ui/src/main/java/com/google/android/exoplayer2/ui/DefaultTrackNameProvider.java
+++ b/library/ui/src/main/java/com/google/android/exoplayer2/ui/DefaultTrackNameProvider.java
@@ -17,6 +17,7 @@
 
 import android.content.res.Resources;
 import android.text.TextUtils;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.util.Assertions;
@@ -100,12 +101,26 @@ private String buildLabelString(Format format) {
   }
 
   private String buildLanguageString(Format format) {
-    String language = format.language;
+    @Nullable String language = format.language;
     if (TextUtils.isEmpty(language) || C.LANGUAGE_UNDETERMINED.equals(language)) {
       return "";
     }
-    Locale locale = Util.SDK_INT >= 21 ? Locale.forLanguageTag(language) : new Locale(language);
-    return locale.getDisplayName();
+    Locale languageLocale =
+        Util.SDK_INT >= 21 ? Locale.forLanguageTag(language) : new Locale(language);
+    Locale displayLocale = Util.getDefaultDisplayLocale();
+    String languageName = languageLocale.getDisplayName(displayLocale);
+    if (TextUtils.isEmpty(languageName)) {
+      return "";
+    }
+    try {
+      // Capitalize the first letter. See: https://github.com/google/ExoPlayer/issues/9452.
+      int firstCodePointLength = languageName.offsetByCodePoints(0, 1);
+      return languageName.substring(0, firstCodePointLength).toUpperCase(displayLocale)
+          + languageName.substring(firstCodePointLength);
+    } catch (IndexOutOfBoundsException e) {
+      // Should never happen, but return the unmodified language name if it does.
+      return languageName;
+    }
   }
 
   private String buildRoleString(Format format) {
diff --git a/library/ui/src/test/java/com/google/android/exoplayer2/ui/DefaultTrackNameProviderTest.java b/library/ui/src/test/java/com/google/android/exoplayer2/ui/DefaultTrackNameProviderTest.java
new file mode 100644
index 00000000000..a5ea81f2597
--- /dev/null
+++ b/library/ui/src/test/java/com/google/android/exoplayer2/ui/DefaultTrackNameProviderTest.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.ui;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.res.Resources;
+import androidx.test.core.app.ApplicationProvider;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import com.google.android.exoplayer2.Format;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/** Tests for the {@link DefaultMediaDescriptionAdapter}. */
+@RunWith(AndroidJUnit4.class)
+public class DefaultTrackNameProviderTest {
+
+  @Test
+  public void getTrackName_handlesInvalidLanguage() {
+    Resources resources = ApplicationProvider.getApplicationContext().getResources();
+    DefaultTrackNameProvider provider = new DefaultTrackNameProvider(resources);
+    Format format = new Format.Builder().setLanguage("```").build();
+
+    String name = provider.getTrackName(format);
+
+    assertThat(name).isEqualTo(resources.getString(R.string.exo_track_unknown));
+  }
+}