Pat chicken pieces completely dry with paper towels—this is critical for proper browning and smoke development. Combine smoked paprika, garlic powder, onion powder, black pepper, sea salt, and brown sugar in a small bowl, mixing well.
Rub the spice blend generously over all chicken surfaces, pressing gently so it adheres. Stir together olive oil, balsamic vinegar, liquid smoke, fresh rosemary, minced garlic, and Worcestershire sauce in a small dish.
Place a large cast iron skillet over high heat for 3-4 minutes until smoking hot—this ensures optimal searing. Brush the hot pan lightly with your oil mixture, then carefully lay chicken pieces skin-side down.
The smoky cast iron grilled chicken recipe requires patience during this stage: do not move the chicken for 7-8 minutes until a deep golden crust forms. Resist the urge to flip early, as this disrupts browning and smoke development.
Flip each piece carefully, brush with remaining oil mixture, and cook the other side for 6-7 minutes until internal temperature reaches 165°F. Squeeze fresh lemon juice over the hot chicken right before serving for brightness.
Transfer finished chicken to a warm plate and let rest for 3 minutes before serving to redistribute juices throughout the meat. Any pan drippings can be spooned over the top for extra flavor and moisture.