Check your pan fit. Place your baking pan in the empty air fryer basket to confirm it fits with some space around the sides for airflow. If it’s tight, choose a slightly smaller pan.

Prep the pan. Lightly grease the pan with cooking spray or butter. For super clean removal, line the bottom with a strip of parchment and grease it too.

Mix the batter. In a medium bowl, combine the brownie mix, eggs, oil, and water according to the box instructions. Stir just until combined. Don’t overmix—streaks of dry mix should be gone, but keep it gentle.

Add extras (optional). Fold in up to 1/2 cup chocolate chips or nuts. If using a swirl like peanut butter or caramel, add the plain batter to the pan first, then dollop and swirl with a knife.

Preheat the air fryer. Set it to 325°F (165°C) for 3–5 minutes. Air fryers run hot; starting slightly lower than oven temp helps prevent over-browning before the center sets.

Fill the pan. Pour the batter into the prepared pan and smooth the top. Tap the pan lightly on the counter to pop large air bubbles.

Bake. Place the pan in the air fryer and cook at 325°F (165°C) for 18–22 minutes. Start checking around 16 minutes. Times vary by air fryer and pan depth.

Test doneness. Insert a toothpick in the center. For fudgy brownies, you want moist crumbs but no wet batter. The edges will look set and slightly pull away from the pan.

Cool before cutting. Let the brownies cool in the pan on a rack for at least 20–30 minutes. This helps them firm up and slice cleanly. For super neat squares, cool completely.

Slice and serve. Lift out using the parchment sling, if used, and cut with a sharp knife. Wipe the blade between cuts for clean edges.