Reeser was born in La Jolla, California, the daughter of Kim (née Handel) and Tom Reeser, the executive director of the television channel KOCT. Reeser performed musical theater in her hometown from the age of six until she left at seventeen. After graduating from Carlsbad High School, she moved to Los Angeles to study at UCLA. Reeser lives in Hollywood, California. She enjoys cooking, scrapbooking, dancing, painting, and playing with her dog, a Papillon named Gatsby after the book The Great Gatsby by F. Scott Fitzgerald. She is currently engaged to her boyfriend Jesse.