Make the marinade: In a bowl, whisk together Dijon mustard, honey, olive oil, garlic powder, paprika, salt, and pepper.
Coat the chicken: Pat the chicken thighs dry. Place in a bowl or zip-top bag, and pour the marinade over them. Toss to coat. For best results, marinate for 30 minutes or up to overnight.
Preheat the air fryer: Set to 380°F (193°C) and let preheat for 2–3 minutes.
Air fry the chicken: Place thighs in the air fryer basket in a single layer, skin-side up. Cook for 18–22 minutes, flipping halfway, until golden and internal temp reaches 165°F (74°C).
Optional glaze: In the last 2 minutes of cooking, brush with extra honey-mustard mixture for a sticky glaze.
Serve: Let rest for 5 minutes, then serve with sides of your choice.