In a large bowl, whisk together the olive oil, lemon juice, parsley, basil, garlic, salt, pepper, and oregano until well combined.
Add the chicken breasts to the marinade, ensuring they are fully coated. Cover the bowl with plastic wrap and refrigerate for at least 30 minutes, or up to 4 hours for more flavor.
Preheat your grill to medium-high heat.
Remove the chicken from the marinade and let any excess drip off. Discard the marinade.
Place the chicken on the grill and cook for 6-7 minutes on each side, or until the internal temperature reaches 165°F.
Remove the chicken from the grill and let it rest for 5 minutes before slicing.