Bell's supermaxi Perpetual Loyal took full advantage when title rival Wild Oats XI withdrew Tuesday, and smashed its fellow 100-foot vessel's fastest winning time to claim line honors.
Bell and co-skipper Tom Slingsby -- an America's Cup winner and Olympic gold medalist -- brought the boat across the line at 2.31 a.m. local time, having completed the 628-nautical-mile race in one day, 13 hours, 31 minutes and 20 seconds.
It beat Wild Oats' 2012 record by four hours, 51 minutes and 52 seconds.
"This is one for the true believers," Bell said after bringing his boat up the Derwent River in the early hours of Wednesday morning.
"We are a proper team of 19 guys, they have all been part of this. From top to tail, so many people have been part of this.
"If I'm honest, I won't be back next year," he added in quotes reported by the race's official Twitter feed.
Bell won the 2011 race on his debut with his previous supermaxi, Investec Loyal, and was runner-up to record eight-time champion Wild Oats two years later.
However, after buying the boat previously known as Speedboat and Rambler -- reputed to be the world's fastest racing supermaxi -- the Sydney accountant suffered early retirements in the 2014 and 2015 events.
This time he recruited half of the crew that took American yacht Comanche to victory last year, and reduced the number of celebrity members on board to just one -- TV presenter Erin Molan.
Like last year, the revamped Perpetual Loyal was first out of Sydney Heads on the traditional race start day -- December 26 -- as Wild Oats made a poor early tactical choice.
However, skipper Mark Richards soon made up lost ground down the east coast of Australia as his boat looked likely to beat its own race record.
Wild Oats was forced to pull out while leading due to the failure of its hydraulic keel control mechanism.
"It was sad to see Wild Oats XI break," Bell said. "We saw them stop. We radioed and asked if they were in trouble. We would have stopped if needed."
Giacomo, a 70-footer owned by New Zealand wine magnate Jim Delegat, crossed the line second just under two hours later.
Hong Kong entry Scallywag -- a revamped version of Bell's 2011 winning supermaxi -- was third.