The first proposal in London's Olympic Stadium took place today and, to the delight of the 20,000-strong crowd, she said "yes".
Charity mascot Wendell Raphael was shown onto a stage, his face beamed onto a big screen, after participating in a parade around the ground.
Thanking his girlfriend for her support of his charity work, Mr Raphael, 40, dressed as a super hero, then said: "This is not an April Fool. Bindi Bhambra, will you marry me?"
She was shown in tears watching from her seat and, to applause from the crowds, nodded her head to say "yes" as the words "She said yes!" flashed onto the screens.
Mr Raphael, known as Raph, said: "When it was confirmed I'd be taking part in the parade two weeks ago, I knew I wanted to propose in front of all these people here today."
He met his fiancée, a 35-year-old teacher from Bristol, on a dating website six months ago.
Mr Raphael, an IT worker originally from Port of Spain, Trinidad, and now living in New Cross, London, also took part in a race at the new stadium during today's Gold Challenge charity test event.
He acts as mascot Super Donor Dan - wearing a red outfit and matching cape - for the African Caribbean Leukaemia Trust to raise awareness of blood and bone marrow donation, and donated a kidney to a friend in 2007.
Asked when the wedding might be, he said with a smile: "I want her surname to be Raphael as soon as possible."
The Gold Challenge sees members of the public compete alongside celebrities and sporting stars.
Miss Bhambra said she has ruled out this summer for their wedding - as her new fiance is carrying the Olympic Torch in Hackney, two days before the games begin, and also taking part in the opening ceremony. Summer 2013 is the likely date instead.
Describing the moment of the proposal, she said: "It was a complete and utter surprise. I saw him in the parade and then all of a sudden he was gone - then I saw him on the big screen.
"I was crying then, because he does so much for charity and I thought that's what he was there for.
"When he proposed, I was bawling tears. I was just amazed - I feel so blessed.
"I always knew I was going to marry him. I just knew.
"I couldn't find him for 15 minutes afterwards, and it felt like such a long time. When I saw him, I couldn't speak. It made me cry again."
The Gold Challenge event saw hundreds of people - many of them schoolchildren - given the chance to run 100m, either as part of a relay or a sprint, after raising money for their chosen charity.
Celebrity runners, including former rugby stars Austin Healey, Gareth Thomas and Mike Catt and singer Sinitta, ran in relays during the event.
There was even a special race for charity mascots, which was won by a runner in a giant daffodil outfit, taking part on behalf of Marie Curie Cancer Care.
Other celebrities inside the stadium for the test event included model Katie Price, present with son Harvey on behalf of Vision Charity, of which she is patron. She said she "couldn't wait" for this summer's games and added: "I'm so honoured that I've been on the track."
The audience enjoyed performances from singers including Dionne Bromfield, god-daughter of the late Amy Winehouse, beat box group The Boxettes and former Britain's Got Talent winner Paul Potts.
As he took to the stage to sing Nessun Dorma, Potts said: "For me, it's amazing to be one of the first performers inside this wonderful stadium."
The Gold Challenge invites people of all ages and abilities to try out either five, 10, 20 or 30 Olympic and Paralympic sports by the end of 2012, raising money as they do so.Suggest a correction