The 1975 Pittsburgh Steelers season was the franchise's 43rd in the National Football League (NFL). The Steelers were defending champions for the first time in their forty-year history and repeated as league champions. The team was led by a dominating defense and a quick offense, and won Super Bowl X over the Dallas Cowboys, 21–17. The 1975 Steelers had one of the greatest defensive teams of all time. The team posted their best defensive numbers since 1946, and scored more points than any other Steelers team, later surpassed by two points in 2010.

In 2007, the 1975 Steelers were ranked as the seventh greatest Super Bowl champions on the NFL Network's documentary series America's Game: The Super Bowl Champions, with team commentary from Lynn Swann, Dwight White, and Mike Wagner, and narrated by Bruce Willis. More than a decade later, the team ranked #10 on the 100 greatest teams of all time presented by the NFL on its 100th anniversary. The 1975 Steelers' +211 point differential stands as the best in franchise history. They won by at least 21 points six times, with their season superlative 37–0 shutout at San Diego in the opener on September 21.