Prepare the grapefruit by removing the peel and white pith thoroughly to minimize bitterness, then break into segments.
Place the grapefruit segments, frozen banana slices, Greek yogurt, almond milk, honey, and vanilla extract into a high-speed blender.
Add ice cubes to the blender jar.
Secure the lid and pulse three times to break up large fruit pieces.
Blend on high speed for 45 to 60 seconds until the texture is completely smooth and emulsified.
Pour into a chilled glass and consume immediately to maintain optimal texture and temperature.