Joseph Ryan Warren (born October 31, 1976) is an American Greco-Roman wrestler and mixed martial artist who most recently competed for Bellator MMA.

During the end of 2008 Warren started transitioning to mixed martial arts, and on March 8, 2009, he made his professional debut.

[5] In 2007 he missed the Pan American Games at Rio de Janeiro because of positive test for cannabis.

On December 18, 2010, it was reported that Warren would be making a return to wrestling, to try to qualify for the 2012 Summer Olympics in London.

[8] Joe Warren started a transition to MMA in 2008 and joined up with Team Quest where he got to train with fellow Greco-Roman wrestler and Pride Fighting Championship Champion Dan Henderson.

[10] In the second round of the tournament, at Dream.9 on May 26, 2009, he was matched up with and defeated former K-1 Hero's Lightweight Grand Prix Champion, and formerly 17–1,[11] Norifumi Yamamoto in his first fight after a 512-day layoff officially due to elbow and knee injuries.

In his scheduled semi-final bout Warren fought Brazilian jiu-jitsu expert Bibiano Fernandes,[14] where he quickly lost due to a controversial first-round armbar after securing a takedown.

[15] Warren advanced to the semi-final round where he defeated Georgi Karakhanyan via unanimous decision at Bellator 18.

On June 24, 2010, Warren won the Bellator featherweight tournament by claiming a split-decision over Patricio Freire.

Along with Smith, many top MMA sites, (MMAJunkie, Sherdog, MMAFighting, MMASpot), all believed that Galvão won the fight by 29–28.

[20] Warren was expected to put his title on the line versus Patricio Freire at Bellator 47 on July 23, 2011, but had to be postponed due to Pitbull's unexpected injury.

[26] After losing the title, Warren returned and faced Owen Evinger on November 9, 2012, at Bellator 80.

[28] On February 5, 2013, it was announced that Warren would be one of the four coaches to appear on the promotion's reality series titled Fight Master: Bellator MMA.

[37] Warren faced Eduardo Dantas in a title unification bout on October 10, 2014, at Bellator 128.

[39] Warren made his first bantamweight title defense against Marcos Galvão in a rematch on March 27, 2015, at Bellator 135.

[43] Warren next faced undefeated prospect Darrion Caldwell in a title eliminator in the main event at Bellator 151 on March 4, 2016.