Union Saint-Gilles (also known as USG Union SG) is one of the oldest football clubs in Belgium. It was founded on November 1, 1897 and in a short time became the leading team in the country.

The club, which is based in Saint Gilles, a suburb of Brussels, has won 11 titles in its history. The first one of them was won in 1903/1904, and the last became a fact in 1935. During this period, Union lifted the Belgian Cup twice (1913 and 1914) and topped the Belgian rankings for trophies won.

An interesting fact is that in the period 1933 - 1935 Union Saint-Gilles recorded 60 games without a loss, which remains an unsurpassed record to this day.

The team's home matches are held at the 8,000-seat Stade Joseph Marien, which was built in 1919. Its last reconstruction was made in 2018.

Union Saint-Gilles plays with yellow shirts and blue shorts, and all-white kit is used for the visits. The ultras faction is called "Union Boys" and has friendly relations with fans of Royal Liege and Cercle Brugge.

Union Saint-Gilles's biggest rivalries are against Anderlecht, RWD Molenbeek and Club Brugge.

In the 2020/2021 season, the club from Saint Gilles won the Second Division and climbed to the elite. With the help of a serious financial investor, Union is among the contenders to play in European tournaments. Although it has a rich history and 11 titles, the team has never played in UEFA tournaments.