The 21-year-old Duplantis, who finished with a silver medal behind world champion Sam Kendricks of the US in 2019, remained the only man to fly over 6m this year.
American Chris Nilsen cleared the bar at 5.97m with his first attempt but could not match Duplantis and picked up the silver medal.
Brazil’s Thiago Braz, who won the title at his home Olympics in Rio de Janeiro five years ago, took bronze with his effort of 5.87m.
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