Costco Meatballs in Marinara Sauce

June 13, 2025

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Costco meatballs in marinara sauce is about as easy as dinner gets. You pour frozen meatballs into the crockpot, add a jar of marinara, garlic, and Italian seasoning, and let the slow cooker do the rest.

It takes about 15 minutes of hands-on time. By dinner, the meatballs are hot and soft and the sauce tastes like it simmered all day, because it did. A handful of Parmesan stirred in at the end makes it rich and cheesy.

Why This Recipe Works

The Kirkland Italian style meatballs from Costco are fully cooked before they are frozen. That means the slow cooker only has to heat them through, not cook raw meat. It is a very forgiving recipe, and it is hard to mess up.

Jarred marinara is a good base, but it can taste a little flat on its own. Fresh garlic and a teaspoon of Italian seasoning wake it up. As the frozen meatballs thaw, they release some of their own seasoning and fat into the sauce, which adds a meaty, homemade flavor.

Stirring in Parmesan at the very end, instead of at the start, keeps the cheese from clumping or turning grainy. It melts right into the hot sauce and gives it a smooth, salty finish.

Ingredients and Easy Swaps

Frozen meatballs: The Costco Kirkland Italian style bag is the classic choice. Any fully cooked frozen meatballs work, including turkey or chicken meatballs.
Marinara sauce: Use your favorite jar. A 24 ounce jar coats about 2 pounds of meatballs. If you use more meatballs, add a second jar so they stay covered.
Italian seasoning: Dried oregano and basil, about 1/2 teaspoon each, can stand in.
Garlic: Two fresh cloves, minced. Jarred minced garlic or 1/2 teaspoon garlic powder also works.
Parmesan: Freshly grated melts best. Pecorino Romano is a sharper swap.
Fresh basil: Optional, but a few torn leaves on top add color and a fresh smell.

How to Make It at a Glance

Add the frozen meatballs to the crockpot.
Pour the marinara over the top. Sprinkle on the Italian seasoning and minced garlic.
Cover and cook on low for 6 hours or on high for 3 hours, until the meatballs are hot in the center (165°F).
Stir in the Parmesan cheese.
Serve over pasta, zucchini noodles, or with garlic bread. Top with fresh basil if you like.

Common Mistakes to Avoid

Not enough sauce. Meatballs that poke out of the sauce can dry out and get tough on top. Make sure every meatball is mostly covered.
Overfilling the crock. Keep the slow cooker no more than two thirds full so the heat moves evenly.
Adding cheese too early. Parmesan cooked for hours can scorch on the bottom and turn stringy. Add it at the end.
Leaving it on warm all day. After cooking, the warm setting is fine for an hour or two. Much longer and the meatballs start to fall apart.

Variations

Meatball subs: Spoon the meatballs into toasted hoagie rolls, top with sliced mozzarella, and broil for 2 minutes until bubbly.
Spicy: Use arrabbiata sauce or add 1/2 teaspoon of red pepper flakes.
Cheesy bake: Move the cooked meatballs and sauce to a baking dish, cover with mozzarella, and bake until melted.
Party appetizer: Keep the crock on warm and serve with toothpicks.
Veggie boost: Add a cup of diced bell pepper or sliced mushrooms at the start.

What to Serve With It

Spaghetti is the obvious pick, but penne, rigatoni, and egg noodles hold the sauce just as well. For a lighter plate, serve the meatballs over zucchini noodles or spaghetti squash. Polenta and mashed potatoes are cozy options too.

On the side, add garlic bread to soak up extra sauce and a simple green salad or roasted broccoli to balance the meal.

This recipe is also a smart pick for game days, potlucks, and busy sports nights. Start it in the morning, set out a pot of pasta and a basket of rolls, and let everyone build their own plate. Leftover meatballs make great lunches the next day, either over pasta or tucked into a sandwich with a slice of provolone.

Make Ahead, Storage and Reheating

Cool leftovers and store them in a sealed container in the fridge for up to 4 days. Reheat on the stove over medium low heat or in the microwave until hot all the way through, about 165°F. Add a splash of water if the sauce has thickened.

This recipe freezes well. Portion the meatballs and sauce into freezer bags and freeze for up to 3 months. Thaw overnight in the fridge before reheating. It is a handy way to stock the freezer with ready meals for busy nights.

FAQ

Do I need to thaw the meatballs first?
No. They go into the crockpot frozen. Since they are fully cooked, they only need to heat through.

How many meatballs should I use?
The Costco bag is large. About 2 pounds of meatballs with one jar of sauce feeds 4 people. Save the rest of the bag for another night, or use more sauce and a bigger slow cooker for a crowd.

Can I make this on the stove?
Yes. Simmer the meatballs and sauce in a covered pot over medium low heat for 20 to 25 minutes, stirring now and then, until hot in the center.

Can I use homemade sauce?
Absolutely. Use about 3 cups of your favorite marinara.