Place watermelon, lime juice, and mint in a blender or food processor. Blend!
Pour into popsicle molds of choice and freeze until solid.
Notes
As long as you are using a seedless watermelon there is no need to strain the mixture. There will be some separation during the freezing process; totally normal. Most popsicle molds will need to be run under hot water for a few seconds after coming out of the freezer.