Spread the popcorn on a baking sheet in a single layer.
Melt the white chocolate chips in the microwave. Start with 20 seconds... then stir. Do another 10 seconds at a time until it is melted. Careful not to burn the chocolate.
Drizzle the popcorn with the white chocolate. While the chocolate is still soft sprinkle the M&M's and sprinkles on top, making sure to get it on the areas with the chocolate so it will stick.
Allow chocolate to harden. Break apart any large pieces and serve.