Mix together olive oil, lemon juice, minced garlic, cumin, paprika, chili powder, salt, and pepper in a bowl until well combined to create the marinade.
Add the chicken pieces to the marinade, tossing to coat thoroughly. Cover and refrigerate for at least 1 hour, or up to 24 hours for maximum flavor.
Preheat your grill or grill pan over medium-high heat until hot, with a slight smoky aroma in the air.
Thread the marinated chicken, bell peppers, and red onion onto skewers, alternating ingredients for color and flavor.
Place the skewers on the hot grill, hearing a satisfying sizzle as the meat and vegetables begin to char and develop grill marks.
Grill the kabobs, turning every few minutes to ensure even charring and cooking, until the chicken is cooked through and vegetables are tender, about 8-10 minutes.
Remove the skewers from the grill and let rest for a couple of minutes, allowing juices to settle and flavors to meld.
Serve the kabobs hot, garnished with fresh herbs if desired, and enjoy the smoky, tender bites packed with flavor.