Place green beans in a pot and cover with water; bring to a boil. Reduce heat to medium-low and simmer until beans start to soften, about 10 minutes. Drain water, leaving beans in the pot.
Place bacon strips on a microwave-safe plate and cook in the microwave until crisp, about 2 minutes. Cool and crumble bacon.
Stir butter and bacon into beans in the pot and return to medium heat; cook and stir until butter melts, 2 to 3 minutes. Add garlic; cook and stir until fragrant, 3 to 4 minutes. Top with lemon zest and stir.
