The Swede's previous world record (6.19m) was set two weeks ago in the same hall.
The Olympic champion was crowned ahead of the Brazilian Thiago Braz (5.95 m) and the American Chris Nilsen (5.90 m).
After two totally missed tries, Duplantis erased the bar at 6.20m on his 3rd and last attempt, capsizing the Stark Arena in the Serbian capital.
It is the third time that Duplantis has improved a world record, which he snatched from Frenchman Renaud Lavillenie in February 2020.
Olympic champion (2021) and European outdoor champion (2018) as well as indoors (2021), the Swedish prodigy (22 years old) had never before been crowned at a world meeting.
He will try this summer in Eugene (July 15-24) to grab the gold medal at the Outdoor Worlds, the only one now missing from his already well-stocked list.
© 2022 AFP