Isner, who also won this tournament in 2010, put 23 aces past Lu for his eighth career championship. It came in his 17th final.
Lu reached the title match by defeating three-time defending champion David Ferrer. This was his first ATP final.
Isner will be the top-seeded American in the men's bracket when the Australian Open begins Monday. He will be seeded 13th.
Beautician charged with giving client fatal silicone butt injection
Ohio bar shooting arrested, charged with murder