In a small bowl, whisk together the dijon mustard, honey, whole grain mustard, minced garlic, smoked paprika, apple cider vinegar, and olive oil until smooth and well combined. Set aside about 2 tablespoons of the sauce for glazing at the end.
Pat the chicken thighs dry with paper towels. Drizzle with olive oil and season both sides with salt, black pepper, and garlic powder. Then spoon the larger portion of the honey mustard sauce over the chicken, coating each piece evenly on all sides.
Preheat the air fryer to 380 degrees F. Place the coated chicken thighs in the basket in a single layer, leaving space between each piece.
Air fry for 10 minutes, then flip the chicken. Brush the reserved honey mustard sauce over the tops of the chicken thighs.
Continue cooking for another 6 to 8 minutes until the chicken reaches an internal temperature of 165 degrees F and the glaze looks sticky and caramelized with golden edges.
Let the chicken rest for 3 to 4 minutes before serving. The honey mustard glaze will thicken slightly as it sits. Serve with roasted vegetables or a fresh green salad.