In a large bowl, add the gochujang, soy sauce, brown sugar, sesame oil, onion powder, and garlic powder. Stir until combined.
Add chicken thighs to the bowl and mix together until chicken thighs are coated in the sauce. Cover and let marinade in the refrigerator for 30 minutes (up to 2 hours).
Preheat the air fryer for 5 minutes at 400 degrees F. Brush or lightly spray the basket with oil.
Add the chicken thighs to the air fryer basket in a single layer. Air fry at 400 degrees F for 13-15 minutes, flipping halfway through.
Remove and plate.
Notes
All air fryers cook differently. Adjust cooking times based on your air fryer and size of the chicken thighs.
Honey or maple syrup could be swapped out for brown sugar.
Different brands of gochujang may have different spice levels. Adjust accordingly based on your desired level of spice.