01 - In a mixing bowl, whisk together olive oil, lemon juice, minced garlic, chopped rosemary, salt, and black pepper until well combined.
02 - Place chicken breasts in a large resealable bag or shallow dish. Pour marinade over the chicken, ensuring all pieces are evenly coated. Seal or cover and refrigerate for at least 1 hour.
03 - Preheat grill to medium-high heat, around 400°F.
04 - Remove chicken from marinade and let excess drip off. Grill chicken breasts for 6 to 7 minutes per side or until internal temperature reaches 165°F and juices run clear.
05 - Transfer grilled chicken to a plate and let rest for 5 minutes before slicing or serving.