After foregoing his last year of college eligibility, Watt was selected by the Steelers in the first round of the 2017 NFL draft.
Watt played in at least 15 games each of his first five seasons with the Steelers, before injuries limited him to 10 games in 2022. In 2021, he recorded 22.5 sacks to match the single-season NFL record set by Michael Strahan in 2001, surpassed by Myles Garrett in 2025. Watt became the second fastest player in NFL history to record 100 sacks, behind Reggie White. He was a finalist for the NFL Defensive Player of the Year award five times (2019–2021, 2023, 2024), winning in 2021. He is the younger brother of three-time NFL Defensive Player of the Year J. J. Watt and former fullback Derek Watt.