Croissy-sur-Seine (French pronunciation: [kʁwasi syʁ sɛn], literally Croissy on Seine) is a commune in the Yvelines department in the Île-de-France region in north-central France.

Croissy contains the two campuses of the British School of Paris,[3] and was Russia's base camp for UEFA Euro 2016.

Croissy is located on a loop of the river Seine, which forms its eastern, southern, and western boundaries.

The commune is home to the 13th century chapel of St Leonard, situated near the banks of the Seine.

The museum presents a collection of paintings, engravings and objects in a beautiful era atmosphere and organizes exhibitions.