Nigeria’s Tobi Amusan finished second in 12.34s. The Netherlands’ Nadine Visser took bronze in 12.39s.
Russell, the Paris 2024 Olympic champion, collected the $150,000 winner’s prize. Amusan earned $75,000 for silver.
The American has been unbeaten in 2026. She broke Amusan’s four-year world record of 12.12s with 12.09s at the Zurich Diamond League in August and also won the Diamond League Final in Brussels.
“Coming back here after hitting the hurdle in 2023 and now being the Ultimate Champion for me it is a way to rewrite the story here,” Russell said, referring to her World Championships exit in Budapest three years ago.
She added: “I didn't have the best start but I think that just attested to how chilly it was. My muscles weren't firing the way that they usually do and it took me a little bit longer to get warmed up but I was able to close the gap.”
Amusan reached the final after running 12.49s in her semi-final. Devynne Charlton of the Bahamas won that heat in 12.45s but finished fourth in the final in 12.40s.
Russell has now beaten Amusan three times this season — in Zurich, Brussels and Budapest. The Nigerian’s silver closes a campaign in which she also took Commonwealth Games bronze after losing the world record she set at the 2022 World Championships in Eugene.
The three-day Ultimate Championship continues in Budapest through Sunday.