Start by placing your frozen meatballs straight into the slow cooker — no thawing needed. This shortcut keeps things simple and works wonderfully because the sauce heats through evenly as they cook.
Next, pour in the chili sauce and grape jelly on top of the meatballs. Give it a gentle stir so everything gets coated. The jelly melts down and combines with the chili sauce to make a glossy, sweet-tangy coating.
Set your crockpot to either Low (4–6 hours) or High (2–3 hours) and let the magic happen. The sauce will get warm and slightly thick, and the meatballs will absorb all those sweet and savory flavors.