Mulkey began practicing
Muay Thai in his 20s under Saekson Janjira at Janjira Muay Thai in
Dallas, Texas. After training there for six months, he moved to
Las Vegas,
Nevada. He turned professional in 2009 after an undefeated amateur career. On August 28, 2010, Mulkey lost via
unanimous decision to Remy Bonnel in
Primm, Nevada. He then lost to Joe Schilling by second round
technical knockout in
Los Angeles, California on December 5, 2012 in a
WBC Muaythai US Super Muddleweight (-76 kg/168 lb) title eliminator. He snapped a two-fight losing streak by defeating Douglas Edwards by TKO in round two in a rematch in Primm, Nevada on February 12, 2011. This was followed up with two back-to-back wins in the space of a month in May 2011 when he beat Ken Tran by unanimous decision in Primm and Phillip Sidkrunoom by TKO due to low kicks in
Thailand. This earned him a shot at the WBC Muaythai International Middleweight (-72 kg/160 lb) Championship against familiar opponent Remy Bonnel on August 20, 2011. After a close fight, Mulkey was decided the victor by split decision to become the new champion. He made the first defence of his title against Simon Chu in Las Vegas on November 19, 2011, taking a unanimous decision over the Englishman. He then went up against
Gregory Choplin in Las Vegas on May 14, 2012. Choplin floored Mulkey and utilised powerful low kicks en route to a unanimous decision which ended Mulkey's five-fight win-streak. He was slated to face
Saiyok Pumpanmuang at
Thai Fight: Pattaya in
Pattaya, Thailand on April 17, 2012 but instead faced Bernueng TopKing Boxing and lost a decision after three rounds. In March 2012, it was reported that Mulkey had signed with
Glory, one of the world's premier
kickboxing organizations, to compete in the 2012 Middleweight Slam tournament. He was replaced by Michael Chase Corley, however, as America's second representative alongside Ky Hollenbeck. He joined
K-1 instead and debuted against
Kit Cope at the
K-1 World Grand Prix 2012 in Los Angeles on September 8, 2012. Cope injured himself while attempting a spinning kick in round two, and Mulkey was able to knock him down three time by attacking his injured leg, which caused the referee to stop the bout and announce Mulkey as the winner by TKO. ==Championships and awards==