Malcolm Sherratt, 64, claimed more than Â£46,000 in disability benefits over eight years, the Department for Work and Pensions (DWP) said.
He had told authorities he needed help dressing and going to the toilet.
Sherratt, from Stoke-on-Trent, was jailed for 12 months after being secretly filmed by the DWP working out at a gym.
He previously admitted two counts of false representation and three counts of making a dishonest representation.
Sherrat, of Arbourfield Drive, began making claims three weeks after taking part in Mr Universe 2007.
He told authorities he needed help cooking and washing and sometimes needed a wheelchair or sticks, the DWP said.
But officials discovered he worked out twice a day and filmed him lifting weights.
Sherratt was sentenced at Stoke-on-Trent Crown Court on Friday.

It follows an upsurge in attacks blamed on the Nigerian militants.
Three suicide bombings killed 33 people in Cameroon's main northern city, Maroua, since last week.
The reinforcements will raise the number of troops deployed to the north to 8,500, AFP news agency reports.
Cameroon's army uses Maroua as the headquarters for its operations against the group.
Authorities in the region have announced several measures, including a ban on wearing the full-face veil, in an attempt to prevent suicide bombers from disguising themselves as devout Muslim women.
They have also closed some mosques and Islamic schools and banned large gatherings of Muslims without permission.
Nigeria's President Muhammadu Buhari is due in Cameroon on Wednesday for talks with President Paul Biya in a bid to strengthen the regional alliance against Boko Haram.
After several months of delay, a multinational force of 8,700 soldiers, police and civilian personnel is due to start operations at the end of July.
It will be based in Chad's capital, N'Djamena, which has also been affected by the violence.
At least 17,000 people have been killed since Boko Haram launched its insurgency in northern Nigeria 2009, according to Amnesty International.
A former Mr Universe contestant who claimed he had a bad back has been jailed for benefit fraud.
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Cameroon will deploy an extra 2,000 troops along its northern border with Nigeria to fight militant Islamist group Boko Haram, state television reports.