Cruickshank made his amateur debut in August 2008 where he defeated Tom Grisham via KO at XCC 11: Duel in Downriver 2. He then went on to compile an amateur record of 8-1 while capturing two titles.

On July 12, 2011, it was announced that Cruickshank signed a contract with Bellator Fighting Championships to fight on their upcoming Summer Series card on July 23. He was to fight Lithuanian fighter Sergej Juskevic but the fight was scrapped at the last minute.

Cruickshank competed on The Ultimate Fighter: Live beginning in March, 2012. In the elimination fight, he defeated Drew Dober by unanimous decision to get into the TUF house. Cruickshank was selected third (sixth overall) by Urijah Faber to be part of his team. In the first fight on the show, Cruickshank was chosen to face James Vick of Team Cruz. Despite controlling much of the action in the opening round, Cruickshank was knocked out with a knee on a takedown attempt.

Cruickshank faced fellow cast member Chris Tickle on June 1, 2012 at The Ultimate Fighter 15 Finale. He won the fight via unanimous decision.

Cruickshank was expected to face Henry Martinez on September 1, 2012 at UFC 151. However, after UFC 151 was cancelled, Cruickshank/Martinez was rescheduled and took place on December 8, 2012 at UFC on Fox 5. He won the fight via spectacular knockout in the second round.

Cruickshank next faced John Makdessi on March 16, 2013 at UFC 158. He lost the fight via unanimous decision. In the final 10 seconds of the Makdessi fight, Cruickshank had his nose badly injured and wound up having surgery to repair what his doctor called “the worst thing he’s ever seen.” He underwent the surgery in May 2013.

Cruickshank faced off against Yves Edwards on July 27, 2013 at UFC on Fox 8, replacing an injured Spencer Fisher. He won the fight via split decision in a closely contested fight.

Cruickshank faced Adriano Martins on November 9, 2013 at UFC Fight Night 32. Martins defeated Cruckshank via submission in the second round.

Cruickshank faced Mike Rio on January 25, 2014 at UFC on Fox 10. He won the fight by wheel kick to the face and punches at 4:56 of the second round.

Cruickshank faced Erik Koch on May 10, 2014 at UFC Fight Night 40. Cruickshank, a significant betting underdog, won the fight via TKO due to a kick and punches in the first round.

Cruickshank faced Jorge Masvidal on July 26, 2014 at UFC on Fox 12. He lost the fight via unanimous decision.

Cruickshank faced Anthony Njokuani on October 4, 2014 at UFC Fight Night: MacDonald vs. Saffiedine. He won the fight by unanimous decision.

Cruickshank faced K.J. Noons on December 12, 2014 at The Ultimate Fighter 20 Finale. After a back-and-forth first round, the fight was stopped in the second round when Cruickshank received a second inadvertent eye poke from Noons and was unable to continue. Because they had not reached the third round, the fight was declared a No Contest.

Cruickshank faced Beneil Dariush on March 14, 2015 at UFC 185. Cruickshank missed weight on his first attempt at the weigh ins, coming in at 157.5 pounds. He was given additional time to make the lightweight limit, but missed weight again, coming in at 157 pounds. Subsequently, he was fined 20 percent of his purse, which went to Dariush. He lost the fight via submission in the second round.

Cruickshank faced James Krause on July 25, 2015 at UFC on Fox 16. He lost the fight by submission in the first round.

Cruickshank faced Paul Felder on January 17, 2016 at UFC Fight Night 81. He lost the fight via submission in the third round.

After losing three straight fights Cruickshank was released from his UFC contract on March 1, 2016.

In March 2016, it was announced that Cruickshank had signed with Rizin Fighting Federation. He made his debut against Shinji Sasaki on April 17, 2016 and won the fight via TKO due to soccer kicks in the first round.

In his second fight for the promotion, Cruickshank faced Dutch kickboxer Andy Souwer on September 25, 2016. He won the fight via submission due to a rear-naked choke in the first round.

Cruickshank was expected to face Chris Brown at WXC 77 on April 24, 2019. However, Brown missed the contracted weight and Cruickshank declined to proceed to the bout.

Cruickshank faced Tofiq Musayev at Rizin 16 – Kobe on June 2, 2019. He lost the fight via unanimous decision.

Cruickshank faced Goiti Yamauchi at Bellator & Rizin: Japan on December 29, 2019. He lost the fight via a rear-naked choke submission in the first round.

While still being under contract with Rizin but unable to enter Japan due to the COVID-19 pandemic, Cruickshank signed a one-fight contract with Taura MMA. He is expected to make his promotional debut against Deivison Ribeiro at Taura MMA 11 on October 30, 2020.