Sadulaev defeated 2016 Olympic gold medallist Kyle Snyder of the United States in the final, 6-0. Mahamed Zakariiev of Ukraine and Mojtaba Goleij of Iran shared the bronze medal.
The gold medal for Sadulaev, who won 97kg gold in Tokyo for ROC and 86kg gold at Rio 2016, is a fifth world title, having previously claimed the 86kg title in 2014 and 2016 and the 97kg gold in 2018 and 2019. He was the 97kg silver medallist in 2017 when Synder took the title.
Tuesday's gold medal round was a rematch of the Tokyo 2020 final, with the same result.
Iran's Kamran Ghasempour held off the Russian Wrestling Federation's Magomed Kurbanov to win gold at 92kg. There was a tie for bronze between American J'den Cox and Azerbaijan's Osman Nurmagomedov.