Conflans-Sainte-Honorine is a commune in the Yvelines department in the Île-de-France region in north-central France. It is located in the northwestern suburbs of Paris, 24.2 km from the center of Paris.
The commune was originally named for its geographic position at the confluence of the Seine and Oise rivers. The village was given the addition "Sainte Honorine" in the 13th century after the female Saint Honorina, whose relics had been kept there since AD 876.
Partly on account of its strategic position, Conflans-Sainte-Honorine is considered the capital of the French inland waterways, and the right bank of the river Seine is still lined with barges. Every year in June, the town celebrates the Pardon national de la batellerie in remembrance of its former importance to inland shipping.