Lœuilly (French pronunciation: [lœji]) is a former commune in the Somme department in Hauts-de-France in northern France.

The first settlement was alongside the river near a drinking trough, fed by a spring, the Blaire fountain.

In 1593, the inhabitants tried in vain to stop the Catholic League coming into the village, which was partially burnt down.

Many watermills, and later, factories powered by the water, sprang up along the river, to take advantage of the natural force.

A mill pond once filled the area near where the Mairie and car-park are found today.