The 220-kilogram bomb was found in late June during construction work near the centre of Rouen in Normandy.
Residents living within a 270-metre radius of the site were told to leave the area early Sunday ahead of the operation, which wound up shortly after 11am.
Discoveries of bombs and shells from World War II are common in France and elsewhere on the continent.
Last month, the French navy defused an unexploded shell found in the sea near a popular beach in Cannes on the Mediterranean coast.
In May, nearly 9,000 people had to be evacuated after a bomb was uncovered in Dresden, Germany, a city which was intensively bombed toward the end of the war.