Which NHL team was the first expansion team to win the Stanley Cup?

The Philadelphia Flyers were the first NHL expansion team to win the Stanley Cup.

The Flyers achieved the breakthrough in the 1973–74 season, only seven years after joining the NHL during the 1967 expansion. They defeated the Boston Bruins four games to two in the Stanley Cup Final. In the deciding sixth game on May 19, 1974, Philadelphia won 1–0 at the Spectrum, with Rick MacLeish scoring and Bernie Parent making a 30-save shutout.

The victory was historically important because post-1967 expansion teams had struggled against the established “Original Six” franchises. Philadelphia had already become the first expansion club to defeat an Original Six team in a playoff series during that run, then completed the achievement by winning the championship.

The Flyers repeated as champions in 1975, defeating the Buffalo Sabres. That second title made them the first expansion franchise to win the Stanley Cup twice. The Pittsburgh Penguins, Los Angeles Kings, and St. Louis Blues all won later.