Whisk together the contents of the lime Jello packet and boiling water in a large mixing bowl until the Jello fully dissolves.
Whisk in the cold water.
Stir in the cool whip topping until fully incorporated.
Pour the pie filling into a prepared 9-inch graham cracker pie crust and spread it out evenly with a spatula.
Place the pie in the refrigerator to chill for at least 6-8 hours or overnight.
Serve as is or garnish with additional whipped topping and lime slices; enjoy!