Preheat oven to 450° F. Wash green beans and trim ends.
Line a rimmed baking sheet with aluminum foil and spread beans on foil.
Pour olive oil over beans and sprinkle on garlic powder. Toss gently to coat beans evenly.
Roast in oven for 10 minutes. Remove baking sheet from oven and redistribute beans for even baking.
Return to oven and bake for approximately 10 additional minutes or until beans have a few golden brown areas. Remove from oven, season with ground pepper and serve.