Whisk honey, soy sauce, garlic, rice vinegar, cornstarch, and water in a small bowl until the cornstarch dissolves completely.
Heat oil in a large skillet over medium-high heat, add the chicken, and spread it into a single layer.
Cook the chicken for 6–7 minutes, turning occasionally, until browned on several sides and almost fully cooked.
Add the zucchini slices and continue cooking for 3–4 minutes until they become tender but still retain some firmness.
Stir the prepared honey garlic sauce once more, then pour it into the skillet and toss everything together.
Simmer for 2–3 minutes until the sauce thickens and coats the chicken and zucchini with a glossy finish.
Remove from the heat and serve immediately over rice, finishing with green onions or sesame seeds if desired.