In a medium bowl, whisk together ketchup, apple cider vinegar, brown sugar, Worcestershire sauce, smoked paprika, garlic powder, onion powder, black pepper, and olive oil.

Make sure the ingredients are fully combined and remain smooth.

Place boneless, skinless chicken thighs into a resealable plastic bag or shallow dish.

Pour the marinade over the chicken, ensuring each piece is well-coated.

Seal the bag or cover the dish tightly, then refrigerate for at least 1 hour; for best results, allow it to marinate overnight.

Preheat your grill to medium-high heat, reaching temperatures around 375°F to 400°F.

Carefully remove the chicken from the marinade, letting any excess drip off. Lightly season both sides with salt.

Place the thighs on the grill, cooking for 6-8 minutes per side.

In the last 2-3 minutes of grilling, baste the chicken with your favorite BBQ sauce.

Cook until the internal temperature reaches 165°F.

Remove the chicken from the grill and tent it with foil. Allow it to rest for 5-10 minutes.

Slice the chicken and serve with additional BBQ sauce.