He was voted in in the annual election that concluded over the weekend.
Two others were in the race: Gergely Nagy, who is studying for a degree in Hungarian grammar and literature; and Moray Allan, a freelance technology consultant.
Nussbaum, who has been a contributor to Debian since 2005, was making his first tilt at the leadership.
The Debian project will mark its 20th birthday in August. Apart from being a very solid distribution in its own right, it is the base for many other distributions and supports more architectures than any other distribution.