Terry Twining, who is a member of the Adjutant General's Corps and has been in the Army for 18 years, averaged one seat every four seconds at Belgium's King Baudouin national football stadium, raising more than £4,000 for charity.
Sergeant Twining, who lives with his family in Gosport, Hants, completed the challenge just weeks after a triple hernia operation and beat the previous record by 790.
He said: "It's brilliant that I've broken the record but my legs are killing me.
"It was hard work but such a relief when it was finally over, and the money is going to a great cause, which is very close to my heart.
"I knew that sitting in all those seats would be an extreme challenge - that's why I decided to do it and I'm just overjoyed that I managed it."
The previous record of 39,250 seats was set at the Rose Bowl stadium in California, USA, in 2007.
To get in shape for the challenge, he sat in all 9,205 seats of RAEC Mons football stadium in Mons, Belgium, in five hours and 30 minutes last August - an average one seat every two seconds.
He raised funds for Marie Curie Cancer Care after his grandfather died of lung cancer and his mother was diagnosed with cancer last Easter.
He has previously run 21 marathons in 21 days, completed 24 hours on a treadmill and done a 24-hour combat fitness test.
This takes his fundraising total from his challenges over recent years to more than £50,000, which has all been donated to good causes.
