Preheat the oven to 350°F (175°C).
Heat olive oil in a large skillet over medium-high heat.
Add the chicken pieces and cook until lightly browned but not fully cooked, about 4-5 minutes. Remove chicken and set aside.
In the same skillet, add diced onion, minced garlic, sliced mushrooms, carrots, and celery. Sauté until vegetables are tender, about 5 minutes.
In a large mixing bowl, combine the rinsed rice, chicken broth, cream of mushroom soup, water, dried thyme, dried parsley, salt, and black pepper. Stir well to combine.
Add the sautéed vegetables and browned chicken pieces to the rice mixture. Stir to distribute evenly.
Transfer the mixture to a greased 9×13 inch casserole dish and spread evenly.
Cover the casserole dish tightly with aluminum foil.
Bake in the preheated oven for 55-60 minutes, or until the rice is tender and liquid is absorbed.
Remove the foil and gently stir in the frozen peas.
Return the casserole to the oven uncovered and bake for an additional 5 minutes to heat the peas.
Remove from oven and let stand for 5 minutes before serving.