Combine all ingredients for the marinade (olive oil, lemon juice, minced garlic, lemon pepper seasoning) in a glass dish or zip-top bag. Add the chicken breasts and marinate in the refrigerator for 4-8 hours.
When you're ready to grill your lemon pepper chicken, preheat the grill to medium-high heat (around 400 degrees F).
Remove the chicken from the marinade. Sprinkle the chicken on all sides with lemon pepper seasoning.
Place the chicken on the grill and cook for 6-8 minutes per side. Remove the chicken once it reaches 160 degrees F. Optionally, you can grill some lemon slices alongside the chicken for a fun garnish.
Cover the chicken loosely with aluminum foil and let it rest for 5-10 minutes. This helps keep the chicken moist when it comes to its final temperature of 165 degrees F.
Serve the chicken with grilled lemon slices or fresh lemon.