Saint-Géry Island (French: île Saint-Géry, Dutch: Sint-Gorikseiland ) was the largest island in the Senne (Zenne) river in Brussels, Belgium. It was named after Saint Gaugericus of Cambrai, who built a chapel there ca. 580. Hence the name "Brussels", which comes from Bruocsella or Broekzele, meaning "settlement in the marsh". It ceased to exist as an island when the Senne was covered over in the late 19th century.
The former island's easternmost edge was more or less due west across Boulevard Anspach from the current . The island was more or less round, and centred on the current Halles Saint-Géry. Many streets and buildings still bear the name.
Saint Gaugericus of Cambrai built a chapel on the island around the year 580. Starting in the 10th century, the church began to house relics of Saint Gudula, who had died two centuries earlier. Later the relics were transferred to the nearby St. Michael and Gudula Cathedral.