Preheat oven to 350°F (175°C) and coat a 9×13-inch baking dish with cooking spray.
In a large mixing bowl, whisk together the rice, water, cream of mushroom soup, cream of chicken soup, chopped onion, red bell pepper, onion soup mix, and oregano until smooth.
Pour the rice mixture into the prepared baking dish, spreading it evenly.
Season the chicken thighs with seasoned salt and arrange them over the rice mixture.
Cover the dish tightly with foil to trap in steam and keep the chicken moist.
Bake for 1 hour and 30 minutes without peeking, then check the internal temperature of the chicken to ensure it reaches 165°F (74°C).