In a large saucepan or slow cooker, combine cranberry sauce, chili sauce, brown sugar, lemon juice, and garlic powder.
Whisk the sauce ingredients over medium heat until the cranberry sauce has melted and the mixture is smooth.
Add the frozen meatballs to the sauce, stirring to ensure each meatball is thoroughly coated.
Cover and simmer for 15 to 20 minutes, or until the meatballs are heated through to an internal temperature of 165°F (74°C).
Transfer to a serving dish and serve warm with toothpicks.