Doerksen started his career in 1999, when he entered the first Bas Rutten Invitational on February 6, 1999, defeating three different opponents by submission before losing to UFC vet Eugene Jackson by submission. His next notable fight was against now-UFC Hall of FamerMatt Hughes at Extreme Challenge 29 on November 13, 1999, losing by second round submission.
In his first fight in the UFC, Doerksen faced Joe Riggs at UFC 49 on August 21, 2004. He lost the fight via second round submission. He then faced Patrick Cote at UFC 52 on April 16, 2005. Doerksen won the fight via rear-naked choke submission. In his third fight with the promotion, Doerksen faced Matt Lindland at UFC 54 on August 20, 2005. He lost the fight via unanimous decision. Doerksen faced Nate Marquardt at UFC 58 on March 4, 2006. He lost the fight via unanimous decision and was subsequently released from the promotion. In November 2006, it was reported that Doerksen had signed a contract with the PRIDE Fighting Championships, but with Zuffa's purchase of the PRIDE organization in the spring of 2007, Doerksen's contract saw him enter the WEC organization instead.
World Extreme Cagefighting
His first fight in the organization was against PRIDE veteran Paulo Filho for the vacant WEC middleweight championship at WEC 29 on August 5, 2007. Doerksen lost the fight via TKO in the first round.
Return to the UFC
Following his loss to Filho, Doerksen returned to the UFC and faced Ed Herman at UFC 78 on November 17, 2007. He lost the fight via third-round KO. In his next fight, Doerksen faced Jason MacDonald at UFC 83 on April 19, 2008. He lost the fight via TKO and was once again released from the promotion.
Post-UFC
After his UFC release, Doerksen signed with World Victory Road promotion in October 2008, and would make his debut against Izuru Takeuchi at on November 1, 2008. He won the fight via TKO. Doerksen defeated Gregory Babene via triangle-choke submission at Canadian Fighting Championship 2 on May 22, 2009. He then returned to WVR and faced Takenori Sato at on September 23, 2009. Doerksen won the fight via KO.
Third UFC stint
Riding a five-fight win streak, Doerksen returned to the UFC to face Tom Lawlor on May 8, 2010 at UFC 113, replacing an injured Tim Credeur. Following a first round in which he was rocked by Lawlor, Doerksen rebounded and won via submission in the second round. Doerksen next faced CB Dollaway on September 25, 2010 at UFC 119. He lost the fight via guillotine choke in the first round. Doerksen then faced Dan Miller on December 11, 2010 at UFC 124. He lost the fight via split decision and was subsequently released from the promotion.
Retirement
Doerksen announced his retirement from MMA competition on August 21, 2015.
Documentary
Doerksen was the subject of a 2013 documentary by filmmaker BJ Verot called Scheduled Violence.
