Gather all your ingredients. Chop the chicken breasts into bite-sized pieces and season with salt and pepper. Slice vegetables as needed.

In a large skillet, heat olive oil over medium-high heat. Add the chicken pieces and sear for 5-7 minutes until golden brown.

Add red onion and garlic to the skillet and sauté for 2 minutes until fragrant. Then add the bell peppers, followed by zucchini after 2 minutes.

Combine the seared chicken back into the skillet with cherry tomatoes and olives. Add the dried oregano and mix well.

Remove from heat and squeeze lemon juice over the stir fry. Top with feta cheese and serve immediately.