Mason Fowler began his athletic journey relatively late, initially competing in rugby during his senior year of high school. After graduation, he joined Thrive MMA, a mixed martial arts gym where he extensively trained in boxing, muay Thai, wrestling, and no-gi jiu-jitsu. Fowler transitioned fully into grappling following an injury sustained during MMA training, prompting him to dedicate himself exclusively to Brazilian Jiu-Jitsu.

Initially introduced to gi jiu-jitsu by brown belt Brian Gonzalez, Fowler significantly evolved his grappling skills under the mentorship of Gabriel Procópio at Dethrone Gym. Procópio played a pivotal role in Fowler's technical growth and oversaw his belt promotions. In 2019, Fowler joined the Caio Terra Association (CTA) to prepare specifically for the 2019 ADCC West Coast Trials. After excelling at the trials, he became a direct student of Caio Terra, who awarded Fowler his black belt. Fowler frequently credits Terra's disciplined, fundamentals-driven approach as instrumental to his competitive success.

Fowler gained international recognition through his dominant performance at the 2019 ADCC West Coast Trials, a form he consistently maintained in subsequent competitions. He became a prominent figure in Chael Sonnen's Submission Underground (SUG) promotion, capturing and repeatedly defending the absolute title. One of his most notable victories occurred at SUG 17 (August 30, 2020), where he defeated renowned grappler Craig Jones via a submission officially recorded as a rear naked choke but effectively functioning as a spine and neck crank. Fowler openly acknowledged strategically utilizing the ruleset to secure the victory.

Technical Approach and Strategy

Fowler is renowned for his wrestling-heavy style and relentless pressure passing in no-gi competition. He integrates extensive cross-training in wrestling and judo to sharpen his takedown capabilities, consistently emphasizing the importance of chaining wrestling techniques into submission opportunities. Fowler attributes much of his competitive success, particularly at ADCC trials, to the deliberate incorporation of wrestling fundamentals and rigorous strength and conditioning into his Brazilian Jiu-Jitsu training camps. His tactical approach allows him to effectively control opponents, systematically advancing positions to secure finishes.

Leveraging his grappling expertise, Fowler transitioned into MMA coaching. In 2025, he was invited by Chael Sonnen to serve as an assistant coach on The Ultimate Fighter Season 33. Joining a coaching staff featuring UFC veterans, Fowler provided elite-level jiu-jitsu insights, significantly contributing to Sonnen's team's overall performance.

Fowler's competitive prominence led to several high-profile superfight opportunities. He was scheduled to face Gordon Ryan in the main event of the UFC Fight Pass Invitational (December 9, 2023), but the match was canceled due to Ryan's injury. Additionally, Fowler withdrew from the ADCC 2024 to compete in the inaugural Craig Jones Invitational, though he later withdrew from the over 80kg division of that event.