Keto Tuna Casserole 

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This keto tuna casserole is a delicious healthy recipe that’s incredibly delicious and made with only naturally low-carb ingredients. With only 3g net carbs per serving, this low carb keto tuna casserole it’s super cheesy and hearty, perfect for a weeknight dinner.

Keto Tuna Casserole

Casseroles are one of my favorite dinner recipes since they are super easy to make using only one dish. Whether you’re craving the classic flavors of a Cheeseburger Casserole, the spicy goodness of a Taco Casserole, or the richness of a Million-Dollar Chicken Casserole, each dish offers its unique appeal. And now, with the addition of this delicious Tuna Casserole to your repertoire, you have even more variety to enjoy.

So if you are looking for an easy and delicious dinner recipe, this healthy tuna casserole checks all the boxes. This dish is both filling and nutritious, made with tender tuna, a delicious blend of spices, and a layer of melted cheese.

What is Tuna Casserole?

Traditional tuna casserole is a beloved classic American recipe consisting of a delicious blend of ingredients such as cooked noodles, canned tuna, a creamy sauce, and sometimes vegetables. However, I’ve taken this traditional recipe to the next level by making it incredibly simple to prepare while adding an extra touch of cheesy deliciousness.

Is Tuna Casserole Keto-Friendly?

Regular tuna casserole is not keto-friendly since it’s made with pasta and breadcrumbs. Still, fortunately, there are many keto-friendly versions of the dish that use low-carb substitutes such as zucchini noodles and almond flour.

Why Are You Going To Love This Keto Tuna Casserole Recipe

  • Budget-friendly and accessible: The low carb casserole recipe is designed to be affordable, utilizing ingredients that are commonly found and reasonably priced. This makes it a cost-effective option for those looking to enjoy a delicious and nutritious meal without breaking the bank.
  • Freezer-friendly convenience: This allows you to save time and effort by having pre-prepared portions readily available whenever needed. Simply thaw and enjoy a hassle-free meal whenever you desire.
  • Time-efficient preparation: With its quick and easy preparation time of just 30 minutes, this casserole recipe is a time-saving option. This not only saves you time but also ensures that you have a quick and nutritious meal option on hand whenever you need it.
  • Versatility for various dietary needs: The Keto Tuna Casserole recipe is highly versatile and can be adapted to fit various dietary needs and preferences. Whether you follow a ketogenic diet, have specific dietary restrictions, or simply want to incorporate more low-carb meals into your routine, this recipe can be customized to suit your individual requirements.
  • Mouthwatering flavors: Loaded with delicious flavors, the Keto Tuna Casserole is a treat for your taste buds. The combination of tender tuna, flavorful cheese, aromatic herbs, and other seasonings creates a dish that is both savory and satisfying. Each bite is packed with a delightful medley of flavors that will leave you wanting more.
  • Meal prep for busy days: an excellent recipe for meal prepping. By preparing it in advance, you can enjoy a nutritious and filling meal on those busy days when you don’t have much time to cook. Simply portion out the casserole into individual servings, store them in the refrigerator or freezer, and reheat whenever you’re ready to eat.
  • Customizable to your taste: The Keto Tuna Casserole recipe provides plenty of room for customization. You can add your favorite spices, herbs, or toppings to enhance the flavors and make them uniquely yours. Whether you prefer a spicy kick, a burst of freshness from herbs, or an extra layer of cheesy goodness, feel free to tailor the recipe to your liking.
Keto Tuna Casserole

Ingredients You’ll Need

Once you see how easy and few ingredients are required to make this delicious tuna casserole, you will want to make it over and over again. Here is a list of everything you will need:

Keto Tuna Casserole Ingredients
  • Canned Tuna in Water – you’ll need 10 oz tuna, so about 2 cans. Place the tuna in a colander while you prep the other ingredients. Feel free to replace it with canned salmon if you’re not a fan.
  • Zucchini – add extra nutrients and flavor to the dish while keeping it low in carbs.
  • Celery – used to add an extra crunch to the casserole.
  • Mayonnaise – you can make it at home or buy it from the store.
  • Mustard – I used Dijon mustard for this recipe, but any other type will also work.
  • Red Onion – you will need one medium onion finely chopped.
  • Mozzarella Cheese – feel free to use your favorite shredded cheese.
  • Salt&Pepper – to taste.
  • Garlic Powder – you can also use fresh minced garlic for an intense flavor.
  • Parsley – fresh chopped parsley to garnish.

How To Make Keto Tuna Casserole?

You will be surprised to see how easy it is to prepare this insanely delicious casserole recipe. Here are the steps that you need to follow:

Preparing The Tuna Mixture

Start by preheating the oven at 400F/200C.

In a large bowl, combine the drained tuna, zucchini, celery, mayonnaise, mustard, chopped onion, salt, pepper, and 1/4 cup of shredded cheese. Use a silicone spatula or spoon to mix all the ingredients together until well combined thoroughly. The creamy mayo and tangy mustard will enhance the flavors of the tuna.

how to make Keto Tuna Casserole

Assemble and Bake The Casserole

Transfer the tuna mixture to a 1-quart casserole dish, spreading it evenly. The dish’s size will ensure proper cooking and allow the flavors to meld together. Sprinkle the remaining shredded cheese on top of the mixture. The melted cheese will create a delicious golden-brown crust.

how to make Keto Tuna Casserole

Place the casserole dish in the preheated oven and bake for approximately 15 minutes or until the top is golden brown. Keep an eye on the casserole to prevent it from overcooking. The baking process will allow the flavors to meld and the cheese to melt, creating a delectable and satisfying dish.

how to make Keto Tuna Casserole

Once the casserole is cooked to perfection, remove it from the oven. Garnish with freshly chopped parsley for a touch of freshness.

Serve the Keto Tuna Casserole while it’s still warm, and enjoy its delightful flavors.

Tips For Making The Best Low Carb Tuna Casserole

  • Use high-quality canned tuna since this is the main ingredient in this casserole recipe.
  • I suggest using solid or chunk tuna rather than flaked tuna. Solid or chunk tuna provides a meatier texture and more distinct fish pieces in the casserole.
  • Avoid tuna packed in oil since it will add unnecessary calories to this dish.
  • To make your tuna casserole turn out perfectly, here’s a helpful tip: cover it with aluminum foil while it bakes. This simple step works wonders by trapping the moisture inside the dish, resulting in even cooking and preventing the top from drying out or getting too browned.
Keto Tuna Casserole

Recipe Variations

  • Spice it up: If you’re craving some heat, try adding a tablespoon of red pepper chili flakes to give your tuna casserole a spicy kick. It’ll add a fiery burst of flavor that’ll make your taste buds tingle with delight!
  • Get cheesy: Take your tuna bake to the next level by using a combination of your favorite cheeses. Whether it’s sharp cheddar, gooey mozzarella, or creamy Gruyere, the melty cheese will add a deliciously indulgent twist to this comforting dish.
  • Veggie power: Boost the nutritional value of your casserole by adding your favorite vegetables. Broccoli, cauliflower, and mushrooms are fantastic options that not only provide a pop of color but also contribute to a healthier and more well-rounded meal.
  • Crunch and flavor: For an extra layer of texture and taste, consider adding crumbled crispy bacon and green onions to your casserole. The crispy bacon will bring a delightful crunch, while the green onions add a fresh and savory note that complements the tuna perfectly.

Serving Suggestions

Even if this keto tuna casserole is enough to create dinner on its own, you can also pair it with various delicious side dishes like:

  • Cauliflower Rice: Serve your tuna casserole alongside some flavorful cauliflower rice. It’s a low-carb alternative that complements the dish perfectly while adding an extra dose of veggies to your plate.
  • Fresh Green Salad: Keep things light and refreshing with a simple green salad as a side dish. A mix of crisp lettuce, juicy tomatoes, and crunchy cucumbers will add a burst of freshness to balance the richness of the casserole.
  • Cauliflower Mashed Potatoes: If you’re craving comfort food, whip up some creamy cauliflower mashed potatoes. It’s a fantastic low-carb substitute for traditional mashed potatoes that pairs wonderfully with the tuna casserole.
  • Roasted Vegetables: Roasting a medley of your favorite vegetables, like zucchini, bell peppers, and asparagus, will create a colorful and flavorful side dish. The caramelized edges and tender textures of the roasted veggies will complement the casserole beautifully.
  • Your Favorite Keto Bread: If you’re in the mood for some bread, choose your favorite keto-friendly bread option. Whether it’s almond flour bread, cloud bread, or flaxseed bread, having a slice on the side will complete your meal.
Keto Tuna Casserole

Storing Keto Tuna Casserole Leftovers

  • Fridge: you can store any tuna casserole leftovers in the fridge in an airtight container for up to 5 days.
  • Freezer: this keto tuna casserole can also be stored in the freezer in a freezer-safe container for up to 2 months. When you’re ready to enjoy the casserole, remove it from the freezer and let it thaw in the refrigerator overnight.
  • Make ahead: Follow the recipe instructions to prepare and mix all the ingredients as directed, then assemble the casserole, and cover it tightly with plastic foil. Store in the fridge for up to 3 days, then bake and enjoy.

More Seafood Recipes

Keto Tuna Casserole

Keto Tuna Casserole

5 from 1 vote

Prep time 15 minutes
Cook Time 15 minutes
Yelds 4 servings
Author Ioana Borcea from LowCarbSpark.com


This keto tuna casserole is a delicious healthy recipe that's incredibly delicious and made with only naturally low-carb ingredients. With only 3g net carbs per serving, this low carb keto tuna casserole it's super cheesy and hearty, perfect for a weeknight dinner.
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  • 2 (5 oz) cans tuna in water drained
  • 1 cup zucchini finely chopped
  • 1 cup celery finely chopped
  • 1 medium red onion finely chopped
  • cup mayonnaise
  • 1 tbsp Dijon mustard
  • 1 cup mozzarella cheese shredded
  • 1/2 tsp sea salt
  • ¼ tsp black pepper
  • ¼ cup fresh parsley chopped


  • Preheat the oven to 400°F/200°C.
  • Mix the tuna, zucchini, celery, mayonnaise, mustard, chopped onion, salt, pepper, and 1/4 cup of shredded cheese in a large bowl.
    how to make Keto Tuna Casserole
  • Transfer the tuna mixture to a 1-quart casserole dish, sprinkle with the remaining shredded cheese. Bake for 15 minutes until golden on top.
    how to make Keto Tuna Casserole
  • Remove from the oven, garnish with fresh chopped parsley, and enjoy.
    how to make Keto Tuna Casserole
Nutrition Facts
Amount per serving.
Total Carbs
Net Carbs

How do we calculate the nutrition info?

These nutrition facts listed are determined using nutrition information from the USDA Food Database. Our nutrition facts are accurate, but if you are using different products, please make your calculations. Net carb count is calculated by subtracting both fiber and sugar alcohols because they don’t raise blood sugar.

Course Dinner
Cuisine American
Keyword Keto Tuna Casserole
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Ioana is a food and travel lover. Her greatest passion is developing mouthwatering recipes that are comforting, easy to make, and budget friendly! She firmly believes that cooking should be fun! About me...

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Recipe Rating

  1. So your instructions were incomplete with the KetoTuna Casserole. When does the celery and Zucchini get added to the recipe?
    Or you could have just said Mix all the ingredients, put into dish and bake.
    Also does the nutrients or macros reflect the total ingredients or without celery and zucchini?

    1. Thank you so much for taking the time to leave a comment on our Keto Tuna Casserole recipe. We truly appreciate your feedback and apologize for the confusion caused by the incomplete instructions. We’re here to help and would be delighted to provide you with the necessary information.

      To clarify, you should add the celery and zucchini to the recipe when you’re mixing all the other ingredients. We apologize for not mentioning this important step in the original instructions. We understand how frustrating it can be when crucial details are omitted. The macros provided do reflect the total ingredients, including the zucchini and celery.

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Hello! My name is Ioana Borcea, and I'm here to provide you with mouthwatering recipes. This blog is all about sharing my favorite tested easy to make, delicious low-carb & keto, nutrient-dense recipes.

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