Prepare the Marinade: In a bowl, mix the barbecue sauce, olive oil, garlic powder, onion powder, smoked paprika, salt, and pepper.
Marinate the Chicken: Place the chicken thighs in a large resealable bag or bowl. Pour the marinade over the chicken, ensuring it's well-coated. Seal and refrigerate for at least 1 hour, or up to overnight for maximum flavor.
Preheat the Grill: Preheat your grill to medium-high heat (about 400°F or 200°C).
Grill the Chicken: Remove chicken from the marinade and place it skin-side down on the hot grill. Cook for about 6-8 minutes, then flip and continue cooking for another 6-8 minutes, or until the internal temperature reaches 165°F (75°C).
Baste with Sauce: During the last few minutes of grilling, brush additional barbecue sauce on the chicken for extra flavor. Remove from the grill and let rest for 5 minutes.
Serve: Garnish with fresh parsley if desired, and enjoy your juicy BBQ chicken thighs with your favorite sides.