Fauja Singh, whose running and style of dress earned him the title "Turbaned Tornado," said Sunday's 6.2-mile race was his final competitive run, CNN reported Monday.
Singh said he completed the Hong Kong event in one hour, 32 minutes and 28 seconds, shaving 4 minutes off his time from last year.
"Five or six kilometers into the race, I really decided to go for it," he said. "I had lots of power today because I was very happy."
Singh said he moved from India to Britain following the death of his son and began running marathons in 2000.
He became the first centenarian to complete a marathon when he ran the Toronto Waterfront Marathon in 8 hours, 11 minutes and 6 seconds in 2011.
"It's because of the happiness I get out of it. If something makes you happy, you'll do it well," Singh said.