Canadian provincial flag consisting of horizontal stripes of red and white bearing an elongated golden lion on the red stripe and three oak saplings and an oak tree on the wide white stripe; the three fly edges of the flag have alternating red and white rectangles.

On July 14, 1769, the new seal for the British colony then known as St. John's Island bore the Latin motto “Parva sub ingenti” (“The small under the protection of the great” or “The small beneath the vast”), which was also represented graphically by an oak tree with three smaller trees at its side. These represented England and the three counties into which the colony was divided. As a province in the Dominion of Canada, Prince Edward Island acquired a coat of arms (arms, coat of) on May 30, 1905, utilizing the old seal design as the basis for its new shield. The red chief (upper part of the shield) bore a yellow lion, which referred to the English origin of the settlers and to the coat of arms of Prince Edward, for whom the island was named.

In anticipation of the confederation centennial celebrations in 1967, a provincial flag was developed from the coat of arms by Conrad Swan, the first Canadian to serve in the College of Arms. The flag is an armorial banner (armorial ensign) with the coat of arms spread out as its field. Along the three outer edges a border of alternating red and white rectangles was added. The flag was approved by the legislature on March 24, 1964.