Adopted on January 21, 1948 at 3 p.m. through an order of the Lieutenant-Governor in Council and accepted as an 'official symbol' the same day. The fleurdelisé flag replaced the Union Jack.

A white cross divides the flag into 4 azure quadrants in which are placed 4 white fleur-de-lis. The fleur-de-lis on azure first appeared under King Louis VII who reigned from 1137 to 1180. The fleur-de-lis had long been used on the Royal Seals. The banner preceeded King Louis everywhere, and he was the only person allowed to display it. In 1534, Jacques Cartier's ship displayed a white cross on a red background. At the same time, a new flag - a white cross on a blue background - was competing for prominence. By 1603, the blue and white flag was flying from Samuel de Champlain's ship as he sailed up the Saint Lawrence River.

In 1946, when Canada replaced the Union Jack with the Red Ensign, the people of Québec were less than pleased. There was nothing in the flag to represent French-Canadians. In 1947, an independent member of the legislative assembly, René Chaloult demanded a new flag which would reflect the French heritage of the province. When the Qué government hesitated in making a decision, Chaloult submitted a resolution on the matter to be discussed on January 21, 1948. There was no debate, however, as Québec Prime Minister Maurice Duplessis entered the legislature at 3 p.m. and announced that the fleurdelisé flag was already flying over the Parliament Building.