Bake boneless chicken thighs in the oven about 25 minutes at 425 degrees. Bake bone-in chicken thighs 30-35 minutes at 400 degrees. Slow-cook chicken thighs for 35 minutes on medium heat. Grill chicken thighs about 15 minutes on medium-high heat. Stir-fry chicken thighs (sliced) 10 minutes on high heat.