Preheat your oven to 400°F (200°C).
In a mixing bowl, combine the olive oil, balsamic vinegar, chili powder, ground cumin, garlic powder, paprika, salt, and pepper. Whisk until well blended.
Place the boneless skinless chicken thighs in the baking dish. Pour the marinade over the chicken, ensuring each piece is generously coated.
Arrange the chicken thighs in a single layer in the baking dish. Bake for 25-30 minutes, or until the chicken reaches an internal temperature of 165°F (75°C).
Once done, remove the chicken from the oven and let it rest for about 5 minutes before serving.
