Ford tipped the scale at 313 pounds before tripping off it and falling into his brother Coun. Doug Ford at the final weigh-in Monday for his "Cut the Waist" challenge.
"I could've done better," Ford said of his weight pledge as he nursed an ankle that he said was twisted in the stumble.
He began the belt-loosening drive at 330 pounds in January when he first stepped onto the large scale set up outside his office.
Ford lost a total of 17 pounds, and said he and his brother will keep trying to lose weight - but without the public weigh-ins.
The Fords had pledged to each shed 50 pounds by the end of June, encouraging Torontonians to join them in slimming down and to donate money to charity for every pound the pair lost.
"We'll keep working hard and cut down," said the mayor, whose weight has fluctuated in the last five months.
Ford appeared at the final weigh-in with his brother despite abandoning his weight-loss pledge and shelving his diet plan in late May. He had missed several of the weekly weigh-ins since then.
Doug Ford followed the mayor onto the scale, which rang in the councillor at 240 pounds - 35 pounds lighter since January.
He said watching what he ate, daily exercise and the motivation of his brother were behind his success losing weight.
"In my opinion? I lost 35 pounds and I didn't really try."
"It took so much nerve for a guy - like both of us who are pretty heavy guys - to come out publicly like this and admit that, you know, we've got a weight issue," he said.
"We're just going to continue on preaching living healthier, eating healthier - and I still have another 20 pounds to go, and I'm not going to stop."
As of Monday, people in Toronto lost 602 pounds alongside the Ford brothers, the challenge website says. More than $21,000 in pledges to charities were made during the campaign.
Rob Ford publicly struggled with his weight during the high-profile challenge. In April, a video of the mayor at a Kentucky Friend Chicken restaurant in Toronto's west end went viral online, sparking both criticism and support of Ford's efforts to meet the weight target.
Speaking to reporters at the weigh-in, Doug Ford stuck by his comments last week that he would run for the Progressive Conservatives if a snap provincial election is called over changes made by the Tories and NDP to the Liberal government's budget legislation.
"I'm ready to run," the mayor's brother said, adding that people in the province don't want an election right now.
"What they want is some transparency and accountability, the same as we've given them here in Toronto."