Gather all ingredients for the Unicorn Marshmallow Popcorn, including air-popped popcorn and butter. Set up your mixing bowl, heat-safe bowl, and lined baking sheets.

Divide marshmallows by color and portion the unsalted butter. This allows for organized melting and coating.

Melt marshmallows (one color at a time) with equal butter in a heat-safe bowl, microwaving in intervals until smooth.

Pour the melted marshmallow over the popcorn. Toss gently to coat each piece evenly.

Add mini fruit marshmallows and sprinkles, folding them into the popcorn for extra fun.

Transfer the coated popcorn to prepared baking sheets to cool for about 30 minutes to 1 hour before serving.