Grab a small bowl and stir together the paprika, garlic powder, salt, pepper, and cayenne if you're using it. This only takes a minute but it's what gives the chicken its flavor base. Set the bowl aside while you prep the chicken breasts.
Pat the chicken breasts dry with a paper towel so the seasoning has something to stick to. If any pieces are noticeably thicker than others, pound them gently to even out the thickness. This one step prevents dry edges and undercooked centers later on.
Spray or brush one side of each chicken breast with oil, then sprinkle on the spice rub and press it in gently with your fingers. Flip the chicken over and repeat the same process on the other side. Pressing the seasoning in really does make a difference in how well it stays put.
Lightly oil the air fryer basket so the chicken doesn't stick during cooking. Place the chicken presentation side down in a single layer, making sure the pieces aren't overlapping or touching too much. Crowding the basket is one of the easiest ways to end up with uneven cooking.
Set your air fryer to 360°F and cook for 10 minutes. Open the basket, flip each piece with tongs, and cook for another 8 to 10 minutes. You're looking for the internal temperature to hit around 160°F before moving to the next step.
Once the chicken is close to done, brush or spoon the BBQ sauce generously over the top and sides. Slide it back into the air fryer for just 1 to 2 minutes, long enough for the sauce to warm through and get sticky without burning.
Pull the chicken out once it reaches 165°F internally and let it rest for about 5 minutes before slicing. Resting keeps all those juices inside the chicken instead of running out onto your cutting board.