diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index 7646e4f42a..1b333bc9ca 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -74,6 +74,8 @@
     *   Assume Dolby Vision content is encoded as H264 when calculating maximum
         codec input size
         ([#8705](https://github.com/google/ExoPlayer/issues/8705)).
+    *   Use an empty string instead of the URI if the media ID is not explicitly
+        set with `MediaItem.Builder.setMediaId(String)`.
 *   HLS:
     *   Fix bug of ignoring `EXT-X-START` when setting the live target offset
         ([#8764](https://github.com/google/ExoPlayer/pull/8764)).
diff --git a/extensions/media2/src/main/java/com/google/android/exoplayer2/ext/media2/DefaultMediaItemConverter.java b/extensions/media2/src/main/java/com/google/android/exoplayer2/ext/media2/DefaultMediaItemConverter.java
index e6d4550d88..57b5ac8b48 100644
--- a/extensions/media2/src/main/java/com/google/android/exoplayer2/ext/media2/DefaultMediaItemConverter.java
+++ b/extensions/media2/src/main/java/com/google/android/exoplayer2/ext/media2/DefaultMediaItemConverter.java
@@ -84,7 +84,7 @@ public class DefaultMediaItemConverter implements MediaItemConverter {
 
     return new MediaItem.Builder()
         .setUri(uri)
-        .setMediaId(mediaId)
+        .setMediaId(mediaId != null ? mediaId : MediaItem.DEFAULT_MEDIA_ID)
         .setMediaMetadata(
             new com.google.android.exoplayer2.MediaMetadata.Builder().setTitle(title).build())
         .setTag(media2MediaItem)
diff --git a/library/common/src/main/java/com/google/android/exoplayer2/MediaItem.java b/library/common/src/main/java/com/google/android/exoplayer2/MediaItem.java
index 68cf30d18f..8e9ecb27d1 100644
--- a/library/common/src/main/java/com/google/android/exoplayer2/MediaItem.java
+++ b/library/common/src/main/java/com/google/android/exoplayer2/MediaItem.java
@@ -147,17 +147,17 @@ public final class MediaItem implements Bundleable {
     }
 
     /**
-     * Sets the optional media ID which identifies the media item. If not specified, {@link #setUri}
-     * must be called and the string representation of {@link PlaybackProperties#uri} is used as the
-     * media ID.
+     * Sets the optional media ID which identifies the media item.
+     *
+     * <p>By default {@link #DEFAULT_MEDIA_ID} is used.
      */
-    public Builder setMediaId(@Nullable String mediaId) {
-      this.mediaId = mediaId;
+    public Builder setMediaId(String mediaId) {
+      this.mediaId = checkNotNull(mediaId);
       return this;
     }
 
     /**
-     * Sets the optional URI. If not specified, {@link #setMediaId(String)} must be called.
+     * Sets the optional URI.
      *
      * <p>If {@code uri} is null or unset no {@link PlaybackProperties} object is created during
      * {@link #build()} and any other {@code Builder} methods that would populate {@link
@@ -168,7 +168,7 @@ public final class MediaItem implements Bundleable {
     }
 
     /**
-     * Sets the optional URI. If not specified, {@link #setMediaId(String)} must be called.
+     * Sets the optional URI.
      *
      * <p>If {@code uri} is null or unset no {@link PlaybackProperties} object is created during
      * {@link #build()} and any other {@code Builder} methods that would populate {@link
@@ -587,10 +587,9 @@ public final class MediaItem implements Bundleable {
                 customCacheKey,
                 subtitles,
                 tag);
-        mediaId = mediaId != null ? mediaId : uri.toString();
       }
       return new MediaItem(
-          checkNotNull(mediaId),
+          mediaId != null ? mediaId : DEFAULT_MEDIA_ID,
           new ClippingProperties(
               clipStartPositionMs,
               clipEndPositionMs,
@@ -1194,6 +1193,12 @@ public final class MediaItem implements Bundleable {
     }
   }
 
+  /**
+   * The default media ID that is used if the media ID is not explicitly set by {@link
+   * Builder#setMediaId(String)}.
+   */
+  public static final String DEFAULT_MEDIA_ID = "";
+
   /** Identifies the media item. */
   public final String mediaId;
 
@@ -1296,7 +1301,7 @@ public final class MediaItem implements Bundleable {
   public static final Creator<MediaItem> CREATOR = MediaItem::fromBundle;
 
   private static MediaItem fromBundle(Bundle bundle) {
-    String mediaId = checkNotNull(bundle.getString(keyForField(FIELD_MEDIA_ID)));
+    String mediaId = checkNotNull(bundle.getString(keyForField(FIELD_MEDIA_ID), DEFAULT_MEDIA_ID));
     @Nullable
     Bundle liveConfigurationBundle = bundle.getBundle(keyForField(FIELD_LIVE_CONFIGURATION));
     LiveConfiguration liveConfiguration;
diff --git a/library/common/src/test/java/com/google/android/exoplayer2/MediaItemTest.java b/library/common/src/test/java/com/google/android/exoplayer2/MediaItemTest.java
index e50ac6ea08..0654eb1c70 100644
--- a/library/common/src/test/java/com/google/android/exoplayer2/MediaItemTest.java
+++ b/library/common/src/test/java/com/google/android/exoplayer2/MediaItemTest.java
@@ -37,19 +37,13 @@ public class MediaItemTest {
 
   private static final String URI_STRING = "http://www.google.com";
 
-  @Test
-  public void builder_needsUriOrMediaId() {
-    assertThrows(NullPointerException.class, () -> new MediaItem.Builder().build());
-  }
-
   @Test
   public void builderWithUri_setsUri() {
     Uri uri = Uri.parse(URI_STRING);
 
     MediaItem mediaItem = MediaItem.fromUri(uri);
 
-    assertThat(mediaItem.playbackProperties.uri.toString()).isEqualTo(URI_STRING);
-    assertThat(mediaItem.mediaId).isEqualTo(URI_STRING);
+    assertThat(mediaItem.playbackProperties.uri).isEqualTo(uri);
     assertThat(mediaItem.mediaMetadata).isNotNull();
   }
 
@@ -58,7 +52,13 @@ public class MediaItemTest {
     MediaItem mediaItem = MediaItem.fromUri(URI_STRING);
 
     assertThat(mediaItem.playbackProperties.uri.toString()).isEqualTo(URI_STRING);
-    assertThat(mediaItem.mediaId).isEqualTo(URI_STRING);
+  }
+
+  @Test
+  public void builderWithoutMediaId_usesDefaultMediaId() {
+    MediaItem mediaItem = MediaItem.fromUri(URI_STRING);
+
+    assertThat(mediaItem.mediaId).isEqualTo(MediaItem.DEFAULT_MEDIA_ID);
   }
 
   @Test