diff --git a/Assets/Tests/InputSystem/Plugins/PlayerInputTests.cs b/Assets/Tests/InputSystem/Plugins/PlayerInputTests.cs
index fabbfe89b4..16e927676f 100644
--- a/Assets/Tests/InputSystem/Plugins/PlayerInputTests.cs
+++ b/Assets/Tests/InputSystem/Plugins/PlayerInputTests.cs
@@ -2165,10 +2165,266 @@ public void TODO_PlayerInput_CanSetUpSplitScreen_AndMaintainFixedNumberOfScreens
 
     [Test]
     [Category("PlayerInput")]
-    [Ignore("TODO")]
-    public void TODO_PlayerInput_CanSetUpSplitScreen_AndManuallyAllocatePlayersToScreens()
+    public void PlayerInput_CanSetUpSplitScreen_AndManuallyAllocatePlayersToScreens()
     {
-        Assert.Fail();
+        var actions = InputActionAsset.FromJson(kActions);
+
+        var playerPrefab = new GameObject();
+        playerPrefab.SetActive(false);
+        playerPrefab.AddComponent<PlayerInput>();
+        playerPrefab.AddComponent<Camera>();
+        playerPrefab.GetComponent<PlayerInput>().camera = playerPrefab.GetComponent<Camera>();
+        playerPrefab.GetComponent<PlayerInput>().actions = actions;
+
+        var manager = new GameObject();
+        var managerComponent = manager.AddComponent<PlayerInputManager>();
+        managerComponent.notificationBehavior = PlayerNotifications.InvokeCSharpEvents;
+        managerComponent.joinBehavior = PlayerJoinBehavior.JoinPlayersManually;
+        managerComponent.playerPrefab = playerPrefab;
+        managerComponent.splitScreen = true;
+
+        var gamepad1 = InputSystem.AddDevice<Gamepad>();
+        var gamepad2 = InputSystem.AddDevice<Gamepad>();
+        var gamepad3 = InputSystem.AddDevice<Gamepad>();
+        var gamepad4 = InputSystem.AddDevice<Gamepad>();
+
+        var playerIndex = 0;
+
+        Assert.That(InputUser.GetUnpairedInputDevices().ToArray(dispose: true),
+            Is.EquivalentTo(new[] { gamepad1, gamepad2, gamepad3, gamepad4 }));
+
+        // Join two players manually and make sure we get two screen side-by-side.
+        managerComponent.JoinPlayer(playerIndex, playerIndex, "Gamepad", gamepad1);
+        playerIndex++;
+        managerComponent.JoinPlayer(playerIndex, playerIndex, "Gamepad", gamepad2);
+        playerIndex++;
+
+        Assert.That(PlayerInput.all, Has.Count.EqualTo(2));
+
+        Assert.That(PlayerInput.all[0].devices, Is.EquivalentTo(new[] { gamepad1 }));
+        Assert.That(PlayerInput.all[1].devices, Is.EquivalentTo(new[] { gamepad2 }));
+        Assert.That(InputUser.GetUnpairedInputDevices().ToArray(dispose: true),
+            Is.EquivalentTo(new[] { gamepad3, gamepad4 }));
+
+        Assert.That(PlayerInput.all[0].splitScreenIndex, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[1].splitScreenIndex, Is.EqualTo(1));
+
+        // Player #1: Upper Left.
+        Assert.That(PlayerInput.all[0].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[0].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[0].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.height, Is.EqualTo(1));
+
+        // Player #2: Upper Right.
+        Assert.That(PlayerInput.all[1].camera.rect.x, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[1].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.height, Is.EqualTo(1));
+
+        // Add one more player and make sure we got a 2x2 setup.
+        managerComponent.JoinPlayer(playerIndex, playerIndex, "Gamepad", gamepad3);
+        playerIndex++;
+
+        Assert.That(PlayerInput.all, Has.Count.EqualTo(3));
+
+        Assert.That(PlayerInput.all[0].devices, Is.EquivalentTo(new[] { gamepad1 }));
+        Assert.That(PlayerInput.all[1].devices, Is.EquivalentTo(new[] { gamepad2 }));
+        Assert.That(PlayerInput.all[2].devices, Is.EquivalentTo(new[] { gamepad3 }));
+        Assert.That(InputUser.GetUnpairedInputDevices().ToArray(dispose: true),
+            Is.EquivalentTo(new[] { gamepad4 }));
+
+        Assert.That(PlayerInput.all[0].splitScreenIndex, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[1].splitScreenIndex, Is.EqualTo(1));
+        Assert.That(PlayerInput.all[2].splitScreenIndex, Is.EqualTo(2));
+
+        // Player #1: Upper Left.
+        Assert.That(PlayerInput.all[0].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[0].camera.rect.y, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #2: Upper Right.
+        Assert.That(PlayerInput.all[1].camera.rect.x, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.y, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #3: Lower Left.
+        Assert.That(PlayerInput.all[2].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[2].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[2].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[2].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Join one more player and make sure we got a fully filled 2x2 setup.
+        managerComponent.JoinPlayer(playerIndex, playerIndex, "Gamepad", gamepad4);
+        playerIndex++;
+
+        Assert.That(PlayerInput.all, Has.Count.EqualTo(4));
+
+        Assert.That(PlayerInput.all[0].devices, Is.EquivalentTo(new[] { gamepad1 }));
+        Assert.That(PlayerInput.all[1].devices, Is.EquivalentTo(new[] { gamepad2 }));
+        Assert.That(PlayerInput.all[2].devices, Is.EquivalentTo(new[] { gamepad3 }));
+        Assert.That(PlayerInput.all[3].devices, Is.EquivalentTo(new[] { gamepad4 }));
+        Assert.That(InputUser.GetUnpairedInputDevices().ToArray(dispose: true), Is.Empty);
+
+        Assert.That(PlayerInput.all[0].splitScreenIndex, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[1].splitScreenIndex, Is.EqualTo(1));
+        Assert.That(PlayerInput.all[2].splitScreenIndex, Is.EqualTo(2));
+        Assert.That(PlayerInput.all[3].splitScreenIndex, Is.EqualTo(3));
+
+        // Player #1: Upper Left.
+        Assert.That(PlayerInput.all[0].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[0].camera.rect.y, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #2: Upper Right.
+        Assert.That(PlayerInput.all[1].camera.rect.x, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.y, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #3: Lower Left.
+        Assert.That(PlayerInput.all[2].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[2].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[2].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[2].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #4: Lower Right.
+        Assert.That(PlayerInput.all[3].camera.rect.x, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[3].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[3].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[3].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Unjoin the player in the upper right and make sure the other players stay where they are.
+        Object.DestroyImmediate(PlayerInput.all[1].gameObject);
+
+        Assert.That(PlayerInput.all, Has.Count.EqualTo(3));
+
+        Assert.That(PlayerInput.all[0].devices, Is.EquivalentTo(new[] { gamepad1 }));
+        Assert.That(PlayerInput.all[1].devices, Is.EquivalentTo(new[] { gamepad3 }));
+        Assert.That(PlayerInput.all[2].devices, Is.EquivalentTo(new[] { gamepad4 }));
+        Assert.That(InputUser.GetUnpairedInputDevices().ToArray(dispose: true),
+            Is.EquivalentTo(new[] { gamepad2 }));
+
+        Assert.That(PlayerInput.all[0].splitScreenIndex, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[1].splitScreenIndex, Is.EqualTo(2));
+        Assert.That(PlayerInput.all[2].splitScreenIndex, Is.EqualTo(3));
+
+        // Player #1: Upper Left.
+        Assert.That(PlayerInput.all[0].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[0].camera.rect.y, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #3: Lower Left.
+        Assert.That(PlayerInput.all[1].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[1].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[1].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #4: Lower Right.
+        Assert.That(PlayerInput.all[2].camera.rect.x, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[2].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[2].camera.rect.width, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[2].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Join a new player but manually allocate the next index.
+        // The split-screen setup goes to 3x2 because we are adding it to the end leaving the second empty
+        managerComponent.JoinPlayer(playerIndex, playerIndex, "Gamepad", gamepad2);
+        playerIndex++;
+
+        Assert.That(PlayerInput.all, Has.Count.EqualTo(4));
+
+        // PlayerInput.all is sorted by playerIndex so the player we just joined should be in the last slot.
+        Assert.That(PlayerInput.all[0].devices, Is.EquivalentTo(new[] { gamepad1 }));
+        Assert.That(PlayerInput.all[1].devices, Is.EquivalentTo(new[] { gamepad3 }));
+        Assert.That(PlayerInput.all[2].devices, Is.EquivalentTo(new[] { gamepad4 }));
+        Assert.That(PlayerInput.all[3].devices, Is.EquivalentTo(new[] { gamepad2 }));
+        Assert.That(InputUser.GetUnpairedInputDevices().ToArray(dispose: true), Is.Empty);
+
+        Assert.That(PlayerInput.all[0].splitScreenIndex, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[1].splitScreenIndex, Is.EqualTo(2));
+        Assert.That(PlayerInput.all[2].splitScreenIndex, Is.EqualTo(3));
+        Assert.That(PlayerInput.all[3].splitScreenIndex, Is.EqualTo(4));
+
+        // Player #1: Upper Left.
+        Assert.That(PlayerInput.all[0].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[0].camera.rect.y, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.width, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Upper Middle will be empty
+
+        // Player #3: Upper Right.
+        Assert.That(PlayerInput.all[1].camera.rect.x, Is.EqualTo(2 * (1 / 3.0)).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.y, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.width, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #4: Lower Left.
+        Assert.That(PlayerInput.all[2].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[2].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[2].camera.rect.width, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[2].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #2: Lower Middle.
+        Assert.That(PlayerInput.all[3].camera.rect.x, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[3].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[3].camera.rect.width, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[3].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Join yet another player and make sure the split-screen setup goes to 3x2.
+        var gamepad5 = InputSystem.AddDevice<Gamepad>();
+        managerComponent.JoinPlayer(playerIndex, playerIndex, "Gamepad", gamepad5);
+        playerIndex++;
+
+        Assert.That(PlayerInput.all, Has.Count.EqualTo(5));
+
+        Assert.That(PlayerInput.all[0].devices, Is.EquivalentTo(new[] { gamepad1 }));
+        Assert.That(PlayerInput.all[1].devices, Is.EquivalentTo(new[] { gamepad3 }));
+        Assert.That(PlayerInput.all[2].devices, Is.EquivalentTo(new[] { gamepad4 }));
+        Assert.That(PlayerInput.all[3].devices, Is.EquivalentTo(new[] { gamepad2 }));
+        Assert.That(PlayerInput.all[4].devices, Is.EquivalentTo(new[] { gamepad5 }));
+        Assert.That(InputUser.GetUnpairedInputDevices().ToArray(dispose: true), Is.Empty);
+
+        Assert.That(PlayerInput.all[0].splitScreenIndex, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[1].splitScreenIndex, Is.EqualTo(2));
+        Assert.That(PlayerInput.all[2].splitScreenIndex, Is.EqualTo(3));
+        Assert.That(PlayerInput.all[3].splitScreenIndex, Is.EqualTo(4));
+        Assert.That(PlayerInput.all[4].splitScreenIndex, Is.EqualTo(5));
+
+        // Player #1: Upper Left.
+        Assert.That(PlayerInput.all[0].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[0].camera.rect.y, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.width, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[0].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Upper Middle will be empty
+
+        // Player #3: Upper Right.
+        Assert.That(PlayerInput.all[1].camera.rect.x, Is.EqualTo(2 * (1 / 3.0)).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.y, Is.EqualTo(0.5).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.width, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[1].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #4: Lower Left.
+        Assert.That(PlayerInput.all[2].camera.rect.x, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[2].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[2].camera.rect.width, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[2].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #2: Lower Middle.
+        Assert.That(PlayerInput.all[3].camera.rect.x, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[3].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[3].camera.rect.width, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[3].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
+
+        // Player #5: Lower Right.
+        Assert.That(PlayerInput.all[4].camera.rect.x, Is.EqualTo(2 * (1 / 3.0)).Within(0.00001));
+        Assert.That(PlayerInput.all[4].camera.rect.y, Is.EqualTo(0));
+        Assert.That(PlayerInput.all[4].camera.rect.width, Is.EqualTo(1 / 3.0).Within(0.00001));
+        Assert.That(PlayerInput.all[4].camera.rect.height, Is.EqualTo(0.5).Within(0.00001));
     }
 
     // https://fogbugz.unity3d.com/f/cases/1260625/
diff --git a/Packages/com.unity.inputsystem/CHANGELOG.md b/Packages/com.unity.inputsystem/CHANGELOG.md
index 0a7ecaf744..a5714222ea 100644
--- a/Packages/com.unity.inputsystem/CHANGELOG.md
+++ b/Packages/com.unity.inputsystem/CHANGELOG.md
@@ -15,6 +15,7 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed an issue causing a number of errors to be displayed when using `InputTestFixture` in playmode tests with domain reloading disabled on playmode entry. [ISXB-1446](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1446)
 - Fixed issue where user was not prompted to save changes when loading a second input actions asset into an already opened editor. [ISXB-1343](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1343)
 - Fixed an issue on macOS which didn't detect up-left DPAD presses for Xbox controllers. [ISXB-810](https://issuetracker.unity3d.com/issues/macos-d-pad-upper-left-corner-is-not-logged-with-the-xbox-controller)
+- Fixed an issue when providing JoinPlayer with a specific split screen index. [ISXB-897](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-897)
 
 ## [1.14.0] - 2025-03-20
 
diff --git a/Packages/com.unity.inputsystem/InputSystem/Plugins/PlayerInput/PlayerInput.cs b/Packages/com.unity.inputsystem/InputSystem/Plugins/PlayerInput/PlayerInput.cs
index 9468230bab..00c09d7bed 100644
--- a/Packages/com.unity.inputsystem/InputSystem/Plugins/PlayerInput/PlayerInput.cs
+++ b/Packages/com.unity.inputsystem/InputSystem/Plugins/PlayerInput/PlayerInput.cs
@@ -1831,7 +1831,7 @@ private void OnEnable()
 
             // Split-screen index defaults to player index.
             if (s_InitSplitScreenIndex >= 0)
-                m_SplitScreenIndex = splitScreenIndex;
+                m_SplitScreenIndex = s_InitSplitScreenIndex;
             else
                 m_SplitScreenIndex = playerIndex;