In a large bowl, combine the garlic and ¼ cup of the teriyaki sauce. Add the chicken, turn to coat, cover, and let marinate for 30 minutes.
Cook the rice according to the package directions.
Meanwhile, heat oven to 450° F. Place the chicken on a foil-lined rimmed baking sheet and roast, basting with the remaining ⅓ cup of teriyaki sauce, until cooked through, 25 to 30 minutes. Ten minutes before the chicken is done, add the bok choy. Serve the chicken and bok choy over the rice.