One of the more experienced lightweights in the UFC, Mac Danzig made his professional debut in 2001 and has fought for KOTC, Pride FC, and the UFC throughout his long career. The first notable achievement of Danzig’s career came in 2005, when he won the KOTC Lightweight Championship and defended it four times. Following a loss to the larger Hayato Sakurai at Pride 33, Danzig was invited to compete in the welterweight tournament of The Ultimate Fighter 6, which he won, before debuting at 155 lbs. with a win over Canadian grappler Mark Bocek by submission.

Danzig experienced a three-fight losing streak from 2008-2009, but since then has gone 3-3 with losses to Matt Wiman and Takanori Gomi and wins over Justin Buchholz and fellow TUF winners Joe Stevenson and Efrain Escudero.

Outside of the cage, Danzig is a vegan and a dedicated animal activist, having appeared in several PETA ad campaigns during his UFC career.

The Ultimate Fighter 6
Episode 1 Danzig def. Joe Scarola by Triangle Choke at 4:54 of Round 1
Episode 9 Danzig def. John Kolosci by Rear Naked Choke at 3:55 of Round 1
Episode 12 Danzig def. John Kolosci by Rear Naked Choke at 4:28 of Round 1
The Ultimate Fighter 6 Finale Danzig def. Tom Speer by Rear Naked Choke at 2:01 of Round 1

On March 4, 2014, Danzig announced his retirement in a letter he released online. Among other things, Danzig cited concern over wear and tear, injuries and concussions suffered throughout his career as primary reasons for his retirement.