Ready in just 15 minutes, this Blackened Mahi Mahi has the perfect combo of a buttery and flaky fish paired with a spicy, crisp crust. Simply sear in a skillet for a delicious Cajun twist on your fish dinner!
London’s Top Tip: A cast-iron skillet gives the fish a perfectly blackened char and imparts the best flavor.
Growing up in Southeast Texas, right on the border with Louisiana, it was inevitable that restaurants would have some sort of blackened fish on their menu. And if I ever spotted blackened mahi mahi? It was a must-order!
The pairing of tender, flaky fish with bold, Cajun seasonings is unlike anything else you’ve ever tasted.
But instead of waiting around to visit the next seafood spot (which are REALLY hard to find now that we live in Austin!), Justin and I decided to recreate that flavor magic at home. And surprisingly, it took us less than 15 minutes!
The trick to making the best blackened mahi mahi?
It’s all in making the Cajun blackened seasoning from scratch. And don’t worry, the ingredients are super simple to find. In fact, you probably already have most of them on hand.
Have extra blackened seasoning? You’ve got to try out this Blackened Salmon recipe, these Blackened Fish Tacos or these Blackened Shrimp next!
Ingredients You’ll Need
Please see the recipe card below for the exact measurements and detailed instructions.
- Mahi-mahi. You want the thicker portion of fish, not the part that’s over the rib cage. This section tends to have lots of little bones that are very difficult to remove and unpleasant to accidentally bite into.
- Blackened seasoning. You can either make your own blackened seasoning at home (which I highly recommend!) or buy a store-bought variety. If you opt for a store-bought kind, make sure you check the sodium content AND the spice level as these can vary drastically.
- Butter. Because butter makes everything better, especially when blackening things! Salted or unsalted work. You can also use a dairy-free vegan buttery stick if avoiding dairy, or even sub for a high smoke point oil such as avocado oil.
- Lemons. These might just seem like a garnish, but they add a lovely note of acidity just before serving to balance out the buttery flavors of the fish.
How to Make Blackened Mahi Mahi
Please see the recipe card below for the full instructions, ingredient amounts, and a printable recipe.
Step 1: Cut and Prep the Fish.
Slice the mahi-mahi into evenly sized filets (super important for consistent cooking!) Then, pat them dry with a paper towel to remove excess moisture—this is my trick that ensures the seasoning sticks and gives you a crispier sear!
Step 2: Season the Filets.
Generously sprinkle the homemade blackened seasoning over the filets. Pat it in thoroughly to ensure it sticks during cooking.
Step 3: Sear in a Cast-Iron Skillet.
Heat butter in a large cast-iron skillet over medium-high heat for 1 minute, or until hot. Add the mahi-mahi skin-side up and cook for 4-5 minutes. Flip and cook skin-side down for another 3-4 minutes, or until the fish flakes easily with a fork and reaches an internal temp of 137℉.
Step 4: Serve with Lemon or Fruit Salsas.
Remove from the heat as soon as the fish is cooked through to avoid drying out. Serve with a sprinkle of fresh parsley and a squeeze of lemon juice, or get fancy and try out this Mango Salsa, Pineapple Salsa, or even Mango Avocado Salsa! (The sweet with the spice is *muah!* So good!)
FAQs
Using a spicy, blackened seasoning gives this flaky white fish the perfect kick. Grilling is also a great options as it imparts a subtle smokiness that also balances out the delicate flavors.
Blackening is all about bold, smoky flavor and that crispy, delicious crust! It’s a Southern cooking technique where fish gets coated in a mix of Cajun seasonings—think paprika, cayenne, garlic powder, thyme, and oregano—then seared in a super hot cast-iron skillet. The high heat gives it that dark, crispy crust on the outside while keeping the inside tender and flaky. And don’t worry, it’s not burnt—it’s just packed with flavor and totally irresistible!
More Easy Seafood Dinner Recipes
Try any of these delicious seafood main dishes next:
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Cajun Blackened Seasoning:
Prevent your screen from going dark
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If making the homemade blackened seasoning: Mix all of the ingredients together in a small bowl or the glass jar you’ll be storing it in.
1 tablespoon paprika, 1 tablespoon garlic powder, 1 tablespoon onion powder, 1 tablespoon black pepper, 1 teaspoon dried thyme, 1 teaspoon cayenne pepper, 1 teaspoon dried basil, 1 teaspoon dried oregano, 1 teaspoon salt
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Cut the mahi mahi into 4 equal-sized filets and pat the fish dry with a paper towel.
1 pound mahi mahi
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Sprinkle the blackened seasoning and salt, if seasoning does not already include it, over the filets and rub it into the fish.
1 tablespoon blackened seasoning, ¼ – ½ teaspoon salt
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Melt butter in a cast-iron skillet over medium-high heat. Wait for at least 1 minute so butter is heated through. Add the mahi mahi to the skillet, skin side-up, and cook for 4-5 minutes. Flip the filets over and continue cooking for 3-4 more minutes or until cooked through.
2 tablespoons salted butter
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Serve blackened mahi mahi with lemon wedges and a sprinkle of fresh parsley, if desired.
Lemon wedges, Fresh parsley
- Blackened Seasoning: The Evolving Table Cajun Blackened Seasoning spice blend was used when testing this recipe. If you opt for another brand (like Slap Ya’ Mama or Tony’s) you’ll need to adjust the amount of salt and seasoning you add depending on your desired spice level.
- Crispy sear: A cast-iron skillet is essential to get that classic, crusty char on the blackened fish.
Calories: 149kcal, Carbohydrates: 1g, Protein: 21g, Fat: 7g, Saturated Fat: 4g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 2g, Trans Fat: 1g, Cholesterol: 99mg, Sodium: 1251mg, Potassium: 474mg, Sugar: 1g, Vitamin A: 389IU, Calcium: 19mg, Iron: 1mg
Nutrition information is automatically calculated, so should only be used as an approximation.
