Place the frozen mixed berries, Greek yogurt, milk, honey, and ice cubes into a high-speed blender.

Secure the lid and blend on high speed for 60 to 90 seconds until the mixture is completely smooth and creamy.

Stop and scrape down the sides of the blender with a spatula if necessary, then blend for an additional 10 seconds.

Pour the thick smoothie evenly into two chilled glass cups.

Serve cold immediately with a reusable straw.