Cook the rice according to the package instructions and set aside.
Steam the broccoli until tender-crisp and keep warm.
Season the chicken pieces with salt and black pepper.
Place a large non-stick skillet over medium-high heat.
Add the seasoned chicken and cook for 6–8 minutes, stirring occasionally, until fully cooked and lightly golden.
In a small bowl, whisk together the brown sugar, soy sauce, vinegar, ginger, garlic, and cornstarch until smooth and free of lumps.
Pour the sauce mixture over the cooked chicken.
Stir constantly as the sauce heats and thickens into a glossy teriyaki glaze.
Continue cooking for 1–2 minutes until the chicken is evenly coated.
Remove from heat.
Assemble the Quick Teriyaki Chicken Rice Bowls Recipe by dividing rice among serving bowls, topping with steamed broccoli and glazed chicken.
Serve immediately while warm.