Heat your air fryer to 400ºF and lightly coat the basket with non-stick spray.
Combine garlic powder, paprika, dried thyme, salt, and brown sugar thoroughly in a mixing bowl.
Dry the chicken thighs with paper towels then evenly rub the seasoning mixture over each piece.
Arrange the chicken thighs skin-side down in the air fryer basket and drizzle them with olive oil; cook in batches if needed.
Cook the chicken for 8 minutes, flip the pieces, then continue cooking for another 8 minutes.
Check that the chicken’s internal temperature reaches between 160ºF and 165ºF and that the skin is nicely crisped; cook 1-2 more minutes if you want crunchier skin.
Allow the chicken to rest for 3-5 minutes before serving.