Bois-Guillaume (French pronunciation: [bwa ɡijom]) is a commune in the Seine-Maritime department in the Normandy region in northern France.

Local legend claims that in 1040 William the Conqueror's mother built a country house on the hill and the area thus came to be known variously as Boscum Guillelmi or Bosco Willelmi, later becoming Bois-Guillaume.

This led to tensions between the urban neighborhoods closest to Rouen (such as Bihorel) and the rest of the commune, which had remained more rural.

[citation needed] In 2010, the municipal councils of Bois-Guillaume and Bihorel began to cooperate more closely, with a view to merging in order to become a single commune once again.

In July 2011, despite opposition among residents of both communes, the merger was approved by the two municipal councils and ratified by prefectoral order on 29 August 2011.