Monger suffered a harrowing Formula 4 crash in 2017 that resulted in his lower legs being amputated.
The British driver returned to racing with the assistance of hand controls less than a year later before taking up a broadcasting career with Channel 4.
After his on-track endeavours ceased, Monger turned his attention to triathlons.
His latest achievement saw him break the double leg amputee course record by more than two hours, finishing in 14 hours, 23 minutes, and 56 seconds.
Monger also became the youngest double leg amputee to compete in the Ironman World Championship.
“What a day! That was the longest day of my life – I just felt so much love out on the course; that was a really special day,” said Monger in Hawaii.
“All that hard work finally paid off and it couldn’t have gone better, everything came together in a really good way.
“There were a few moments – getting stung by jellyfish and getting a cut on my run socket but all things considered, issues we could have had, I am absolutely chuffed – it was a race I couldn’t have dreamed of.
“My support team as always absolutely killed it so big thanks to them. I hope you guys have loved the journey as much as I have and we are an IRONMAN! A course record by two hours? That’ll do!”
Monger is raising money for Comic Relief. In 2021, he raised $6.3 million for the charity.
HE DID IT! 🔥🏁@BillyMonger battled jellyfish stings, intense humidity and torrential rain to SMASH the existing Ironman World Championships course record for a double leg amputee by over 2 HOURS!
Give it up one more time for BILLY MONGER 👏
Donate now: https://t.co/PELrCMMyHe pic.twitter.com/hF2jtsdYlP— Comic Relief (@comicrelief) October 27, 2024