Zverev secured his spot for the Turin event after Dutchman Tallon Griekspoor withdrew from their quarter-final clash in Vienna, where the German world number three is seeded second.
Zverev, who finished as runner-up at the Australian Open in January, joins Carlos Alcaraz, Jannik Sinner and Novak Djokovic as the first four players to qualify for the event, which runs from November 9th-16th. Four spots are up for grabs.
The 28-year-old has enjoyed success at the ATP Finals, lifting the trophy in 2018 and 2021. He also reached the semis in 2019 and 2024. His only absence from the tournament since 2017 came in 2022, when a serious ankle injury sidelined him for much of the season.