The 24-year-old world silver medallist held that mark through four rounds at the National Athletics Centre. Home favourite Bence Halász took silver with 80.30m. Ukraine’s Mykhaylo Kokhan earned bronze with 78.90m.
Olympic and world champion Ethan Katzberg of Canada failed to record a valid throw and was eliminated after two rounds.
Hummel almost matched his opener in round three with 81.44m. None of the four athletes who reached the final round improved, so the German’s first effort stood as the winning distance.
He collected $150,000 from the meeting’s $10 million prize pot.
“It is so overwhelming,” Hummel said. “Just two years ago I was in the top eight in the world, so then I was overwhelmed with the silver medal at the World Championships last year. I am used to being in the top three now, but winning the Ultimate title feels very special.”
He added that athletes “had problems with the wet circle” and that he had fallen once. “I just had to adapt to the competition and stay relaxed.”
At the stadium microphone he described the win as “fantastisch” and said: “Now to take gold is refreshing and I can get used to it, definitely.”
Hummel gained revenge on Halász, who had beaten him to European gold in Birmingham last month. Katzberg had arrived on a seven-meet winning streak.
The three-day inaugural championship continues in Budapest through Sunday.