Add the grape jelly and the bbq sauce to the slow cooker and whisk together to combine.
Add in the meatballs and toss in the sauce.
Cook on low for 4 hours.
Note: If you are in a hurry and would like to speed this up. Add all of the ingredients to a large saucepan on the stove and heat over medium heat for about 10 minutes while stirring. Once the meatballs are warmed throughout, you can add everything to the slow cooker and keep on warm to serve.