Fix: Mixamo Animations Broken After Retargeting to the UE5 Mannequin

Mixamo is the fastest way to get placeholder or even final animations onto a UE5 character, and UE5's retargeting tools have become much better at it. The remaining problems are predictable, because the Mixamo skeleton differs from the UE5 Mannequin in three specific ways.

Why Mixamo is different

• Rest pose: Mixamo characters are in a T-pose; Manny and Quinn are in an A-pose. A retarget that assumes the poses match rotates every arm animation by the difference, which is where twisted shoulders and arms through the body come from.
• No root bone: the Mixamo hierarchy starts at mixamorig:Hips. Unreal's root motion needs a root bone at the ground.
• Naming and proportions: different bone names, finger structure and limb lengths.

Step 1: download and import correctly

1. In Mixamo, download one animation With Skin (FBX Binary) to get the skeleton, and the rest Without Skin.
2. For locomotion, decide now: tick In Place if you will move the character with Character Movement (the usual choice), untick it if you need root motion.
3. Import the With Skin file as a skeletal mesh to create the Mixamo skeleton, then import the other animations onto that skeleton.

Step 2: retarget with aligned poses

In recent UE5 versions you can right-click the Mixamo animations and choose Retarget Animations, pick the Mixamo mesh as source and Manny as target, and let the editor generate the IK Rigs and retargeter. If the preview looks wrong, open the generated IK Retargeter and fix the pose:

• Switch to Edit Retarget Pose for the target (or the source) and use the auto-align option to match bone directions between the two skeletons, or manually rotate the upper arms down until the T-pose and A-pose line up.
• Check the arms in the preview at frame 0 of a neutral animation: hands should be in the same place on both characters.

Step 3: check chain mapping

In the retargeter's chain mapping list, every source chain should map to the matching target chain: Spine to Spine, LeftArm to LeftArm, each finger to its finger. Auto-mapping usually gets this right; when one limb is wrong, it is usually a chain mapped to the wrong side or to None. Mixamo fingers have one fewer bone than the Mannequin's, which is fine as long as the chain endpoints are correct.

Step 4: hips, height and root motion

• Character floating or sunk into the floor: adjust the retarget root (pelvis) settings in the retargeter so vertical translation scales to the target's proportions.
• Feet sliding or not planting: enable the IK goals for the feet in the target IK Rig so the retargeter can keep them planted.
• Need root motion: Mixamo clips carry the motion on the hips, so Unreal sees no root motion. Add a root bone before import with a Blender add-on or a converter tool built for Mixamo-to-Unreal root motion, then retarget.
• Using In Place clips: make sure the Character Movement component's speeds match the animation, and use stride or orientation warping to hide the rest.

Step 5: export and verify

Export retargeted animations from the retargeter (or the Retarget Animations dialog) into a folder for the Mannequin skeleton. Spot-check a walk, a run and something with arms above the head; those three reveal nearly every remaining pose or chain mistake.

Animation bugs players notice

Players rarely describe animation bugs precisely. Bugnet's Unreal SDK lets your UMG menu call ReportBug() to file a report with a screenshot and the player's context, which turns “my arms went weird when I climbed” into something you can find.

Related problems

• How to Fix Unreal Runtime Retargeting Stretching the Arms Because the IK Rig Chain Mapping Is Wrong
• How to Fix Animation Retargeting Issues Between Rigs
• Fix: Unreal MetaHuman Rig Broken After Retarget
• How to Fix Control Rig Foot IK Sliding During Locomotion in Unreal

Frequently asked questions

Why are the arms twisted after retargeting Mixamo animations in Unreal?

Mixamo uses a T-pose and the UE5 Mannequin uses an A-pose. Align the retarget pose in the IK Retargeter so the arms match before exporting.

Do Mixamo animations have root motion in Unreal?

Not by default. Mixamo has no root bone, so motion is on the hips. Add a root bone before importing, or use In Place clips with Character Movement.

How do I retarget Mixamo animations to Manny in UE5?

Import the Mixamo character and animations, right-click the animations, choose Retarget Animations, select the Mixamo mesh as source and Manny as target, check the retarget pose and chain mapping, then export.

Fix the retarget pose before touching anything else. Most "broken" Mixamo retargets are a T-pose against an A-pose.