In a bowl, whisk together the olive oil, lemon juice, garlic, oregano, salt, and pepper.
Add the chicken cubes to the marinade and toss to coat. Marinate for at least 30 minutes, or up to 4 hours in the refrigerator.
Assemble the Kabobs
Thread the chicken, bell pepper, and red onion onto skewers, alternating ingredients.
Grill the Kabobs
Preheat grill to medium-high heat. Grill the kabobs for about 12-15 minutes, turning occasionally, until the chicken is cooked through and the vegetables are tender.
Notes
Serve immediately with your favorite sides, like rice or a fresh salad.