Gather all the ingredients listed above to make the process smoother.
In a large mixing bowl, combine the marshmallow fluff, sweetened condensed milk, key lime juice, and lime zest. Stir until smooth.
In a separate bowl, whip the heavy whipping cream until stiff peaks form. Be careful not to over-whip.
Gently fold the whipped cream into the key lime mixture using a spatula.
Transfer the dip to a serving bowl, cover with plastic wrap, and chill in the refrigerator for at least 30 minutes.
Serve chilled with fresh fruits like strawberries, pineapple, kiwi, and apple slices. Garnish with additional lime zest.