Cut half of blueberries crosswise into thin slices, then cut the rest in half. Divide berries among 6 (1/3 cup) popsicle molds*. Add lemonade (don't insert sticks yet). Cover and freeze until slushy, about 1 1/2 hours.
With a chopstick or table knife, stir popsicle mixture to distribute berries. Insert popsicle sticks and freeze until solid, at least 3 hours more.
To remove popsicles from molds, either let sit at room temperature 5 minutes or run under warm water 10 to 15 seconds.
*We used the Prepworks by Progressive Freezer Pop Maker ($15; shop.cocktail builder.com/collections/all).
Make ahead: Up to 2 weeks, frozen.