In a medium bowl, whisk together the honey, Dijon mustard, apple cider vinegar, garlic powder, salt, and pepper until well combined.
Place the chicken thighs in a large resealable plastic bag or a glass container. Pour the honey mustard marinade over the chicken, ensuring each piece is well coated.
Preheat your oven to 425°F (220°C).
Remove the chicken from the marinade, allowing any excess to drip off. Place the chicken thighs skin-side up on a baking sheet lined with parchment paper.
Bake in the preheated oven for 25-30 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and the skin is golden brown and crispy.
In the last 5 minutes of cooking, brush the reserved marinade over the chicken thighs.
Once done, remove the chicken thighs from the oven and let them rest for about 5 minutes.
Plate the chicken thighs and drizzle any remaining sauce from the baking dish over the top.