He is a former professional triathlete, representing the United States on the ITU Triathlon World Cup circuit, racing in 25 countries on six continents from 2009 to 2015.

On December 26, 2018, he completed a solo crossing of the land mass of Antarctica, excluding the ice shelves, using the South Pole Traverse (SPoT) vehicle road during the last 366 miles (589 km) of the journey.

In late 2009, encouraged by his mentor, financier Brian Gelber, O'Brady quit his job to pursue a career as a professional athlete.

[2] O'Brady aimed to conquer the Explorers Grand Slam (Last Degree), an adventurer's challenge to climb the highest mountain on each of the seven continents and complete expeditions to both the North and South Poles in world record time.

O'Brady and Besaw financed the Grand Slam attempt through sponsorships from Gelber Group, Nike, Columbia Sportswear, and Mountain Hardwear, among others.

[2] The project raised funds and awareness to benefit the Alliance for a Healthier Generation, a non-profit organization that aims to combat childhood obesity.

[citation needed] O'Brady was joined on parts of his Beyond 7/2 journey by various climbing partners and as a paying client with guides including polar explorer Eric Larsen, Vern Tejas and fellow mountaineer Maria (Masha) Gordon.

[citation needed] O'Brady became the fastest person (male) to complete the Explorers Grand Slam (Last Degree) when he reached the summit of Denali in Alaska on May 27, 2016, and set a new speed record of 139 days.

While reaching each high point, he invited local residents of all ages and backgrounds to come out to join him in setting a new world record; this piece of the project was coined "The Forrest Gump Effect".

[32][33] In December 2019, O'Brady acted as the first mate in a six-man team on the first man-powered crossing of Drake Passage, the body of water between South America and Antarctica.