Biker Build-Off is a reality television series for the Discovery Channel. Created and narrated by Thom Beers, the series was originally conceived as a single special called The Great Biker Build-Off. The show proved so popular that more episodes were produced in succeeding years, to the point that it was turned into a regular series (and its name shortened to just Biker Build-Off) in 2005.

Two reputed custom motorcycle builders from different parts of the country—usually with very different styles of building—each build a unique custom bike in their respective style, pitting their teams and expertise against each other to see who is the better builder.

Biker Build-Off was originally an irregularly-grouped series (termed "rounds") of contests that spanned a calendar year. The original Great Biker Build-Off was a single competition. In 2003, the second round had three contests, and the third round (2004) had six. In 2005, the program was turned into a regular series in which each round would feature a total of 13 contests each. There has also been a World Biker Build-Off special (pitting three international bikers) in 2004.

Various aspects of the rules have evolved over the course of the series. When the show became a regular series, the current rules of the Biker Build-Off were defined as follows:

1. Each builder has 10 days to build a working custom motorcycle in his or her respective style.

2. Upon completion, the two builders bring their bikes to a mutually-agreed neutral location.

3. When they meet, the two builders and their teams will begin a lengthy ride to a bike show.

4. At the bike show, the two bikes will be showcased and a winner decided by an audience ballot.