[9] Larratt entered his first international competition, competing at WAF Worlds event in Japan, where he defeated Krister Jonsson and lost to John Brzenk.

[19][20] In 2004, Devon Larratt once again dominated the Central Ontario Championships, but lost a super match in Chehalis, Washington against John Brzenk.

[24] In 2006, after returning from a six-month deployment, Larratt defeated Ron Bath 3–1, at a Mike Gould Classic event in Ontario, Canada.

At the time Ron Bath was considered the #3 ranked heavy weight in North America, behind only John Brzenk and Travis Bagent.

Devon Larratt has stated that this was his favorite match, "for a number of reasons", but mostly because of the difficulties and stressors of combat, and the uncertainty of returning to a "normal life".

[26] Months later, Laratt faced the Ukrainian champion Taras Ivakin at Professional Armwrestling League (PAL) Vendetta/Armfight #26 and lost, 2-4.

[38] In 2010, Devon Larratt beat Travis Bagent 4–3, Tim Bresnan 5–1, and Don Underwood 4–3, to become the #1 ranked arm-wrestler in the world (both left and right).

[39][40][41] In 2010, Devon Larratt defeated former Arnold Classic champion and number one contender, Don Underwood, to retain the right-hand title.

[47] In 2013, Larratt beat Oleh Zhokh, Wilton Brock, and Eric Woelfel at Ultimate Armwrestling League 4 (UAL 4) to retain his left hand heavyweight title.

[52] He underwent a similar procedure on his left elbow in 2016, but was able to recover much faster, returning to win the WAL championship in the same year.

[64][65][66] In 2017, Larratt retained the WAL right-hand and left-hand heavyweight titles by defeating perennial rival Matt Mask.

[69][70][71] On May 17, 2018, at WAL 402, Larratt defeated American super heavyweight "Big Daddy" Jerry Cadorette, 3–2, in a right handed supermatch.

[81] In July 2019, at WAL 504, Larratt beat Dave Chaffee 3–1, displaying an impressive king's move and much improved strength.

[85] On May 28, 2021, less than five months after recovering from deep vein thrombosis, Devon Larratt agreed to meet Michael Todd at King of the Table (KOTT) in Dubai for the right-hand heavyweight title.

[86] In one of the most hyped matches of all time, Larratt avenged his 2018 loss in dramatic fashion by defeating number one ranked Michael Todd 6–0.

[90][91] On December 11, 2021, at King of the Table II, Devon Larratt beat John Brzenk 4-0 for the right-hand heavy weight title.

[94][80] On August 16, 2021, Devon Larratt accepted a boxing match with the World's Strongest Man Champion Hafþór Júlíus Björnsson.

[95] Larratt, who had no previous boxing experience, trained for the match at Tristar Gym, owned by Firas Zahabi.

The gym is notable for training a number of top mixed martial artists, including UFC Hall of Famer Georges St-Pierre.

Devon participated in this match because Prudnik's originally scheduled opponent (Michael Todd) had to withdraw due to injury.

[103] In a pre-recorded [104] Arm Wars Dark Card event that aired on February 4, Devon Larratt faced Sandris Sedis twice, both in right and left handed matches.

[107] Immediately after the Genadi match, Devon Larratt traveled to the UK for Arm Wars Dark Card 2.

On June 10, Larratt continued his left hand winning streak by defeating Bulgarian champion Yordan Tsonev at Be Strong Armwrestling 4.

An underdog in this bout, Devon would decisively defeat Gasparini 5 - 0 to become, at age 48, the oldest Super-Heavyweight champion in arm wrestling history.

[116] On August 30, Devon Larratt defeated Georgi Tsvetkov 6-0 in a long and hard fought left handed match at Arm Wars Dark Card 3.

[121] Larratt would start the year competing on the left hand at the Arm Wars The Gathering II event in Las Vegas.

On January 5, in an exhibition supermatch leading up to the event, Larratt would defeat the 3rd-ranked American Super-Heavyweight Pavlo Derbedyenyev 3-1.

On 20th of April, Devon Larratt faced Levan Saginashvili in a rematch at East vs West 12, in a right handed best of 7 supermatch.

Oftentimes, he only needs to stop the initial surge of his opponent in order to hold them in a disadvantageous position, tire them as the match progresses, and eventually pin them.