How to Create Rounded Video Overlays in CapCut

On CapCut mobile, you round the corners of a clip with a Rectangle mask, then fill the empty space around it with a blurred background. The mask shapes the clip, and the blur replaces the black bars that CapCut leaves in a vertical frame.

Round the corners with a Rectangle mask and blur background

1. Create a new project and add your clip.
2. Tap Ratio and choose TikTok, the 1080 by 1920 vertical setting. The clip now sits in a tall frame with black space around it.
3. Tap the clip to select it, tap Mask, and choose Rectangle.
4. Drag the corner handles on the mask to size the frame and round its corners.
5. Tap an empty spot on the preview so nothing is selected and you're back at the main editing menu.
6. Tap Background, choose Blur, and pick a light blur. The black space turns into a soft, blurred copy of your video.

If that doesn't work: darken a copy of the video underneath

This method skips the Background menu. You stack two copies of the same clip instead.

1. Add your clip to the timeline and shrink it with the corner handles so it sits inside the frame with room around it.
2. Tap the clip, tap Mask, choose Rectangle, and drag the handles to round the corners.
3. Tap the clip again and duplicate it so you have two copies of the same video.
4. Move the copy to the bottom layer so it sits underneath the rounded clip.
5. Darken the bottom copy using the adjustment settings, or add a blur to it. The rounded clip stays sharp on top.

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