The year 2005 was the 13th year in the history of the Ultimate Fighting Championship (UFC), a mixed martial arts promotion based in the United States.

The reality TV series The Ultimate Fighter and the first UFC Ultimate Fight Night both premiered on Spike TV.

The Ultimate Fighter 1 Finale was the first live UFC broadcast on non-pay-per-view television.

The following fighters fought their first UFC fight in 2005:

UFC Ultimate Fight Night (also known as UFC Fight Night 1)[5] was an event held on August 6, 2005 at the Cox Pavilion in Las Vegas, Nevada.