Preheat the oven. Set your oven to 350°F (175°C). Prepare a nonstick baking sheet for the meatballs.
Prepare the meatball mixture. In a large mixing bowl, combine the ground beef, bread crumbs, minced onion, water, and egg. Mix gently until all ingredients are evenly incorporated.
Shape the meatballs. Roll the mixture into small, evenly sized meatballs and arrange them in a single layer on the prepared baking sheet, leaving a little space between each one.
Bake the meatballs. Place the baking sheet in the preheated oven and bake for 20–25 minutes, turning the meatballs once halfway through cooking. Bake until browned and cooked through, reaching an internal temperature of 160°F (71°C).
Prepare the cranberry chili sauce. While the meatballs bake, combine the jellied cranberry sauce, chili sauce, brown sugar, and lemon juice in a large saucepan over low heat.
Stir until smooth. Heat the sauce gently, stirring occasionally, until the cranberry sauce melts and the ingredients form a smooth, evenly blended mixture.
Add the cooked meatballs. Transfer the baked meatballs into the saucepan, stirring gently to coat them evenly with the sweet and tangy sauce.
Simmer the meatballs. Keep the saucepan over low heat and allow the meatballs to simmer in the sauce for 1 hour. Stir occasionally to prevent sticking and maintain an even coating.
Serve warm. Transfer the meatballs to a serving dish or keep them warm in a slow cooker. Serve with toothpicks for an easy party appetizer.