FC Sion was established in 1909 by a former club captain, Robert Gilliard. They played their first matches in the same year, but would not enter competitive league football until 1914. Over the years, Sion have enjoyed significant success at domestic level, especially in cup football. In recent times, they have also represented their country in continental football.
The club spent several decades playing in the lower leagues in Switzerland and, for the full duration of the 1930s, competed in the country's fourth tier. By the late 1950s, they had risen to the second division and in 1962, they gained promotion to the top flight for the first time.
Sion enjyoed their first taste of major success a few years later, in 1965, when they lifted the Swiss Cup. Further cup successes followed in 1974, 1980, 1982 and 1986. The 1990s represent the team's golden era. In 1991, Sion lifted their sixth Swiss Cup, while in 1991–92, they were crowned as league champions for the first time. The 1996-97 season brought about the side's greatest ever achievement, as they won both the league title and the Swiss Cup, completing a domestic double. Since the turn of the 21st century, Sion have added further cup wins in 2006, 2009 and 2011. The team's success in cup competitions has written them into the history books. Remarkably, they have never lost a domestic cup final, having won in all 12 of their Swiss Cup final appearances to date.
Amongst the most notable footballers to have played for the club over the years are names like Vladan Lukić, Gelson Fernandes and Gennaro Gattuso.
Sion play their home matches at the Stade Tourbillon. The venue first opened in 1968 and was redeveloped during the late 1980s. It is currently able to hold up to 16,263 supporters.