The flag is based on the provincial coat of arms, which was itself inspired by the Scottish Cross of St. Andrew (white saltire on a blue field) and the royal arms of Scotland. The “reverse-colour” Cross of St. Andrew on the Nova Scotia flag provides a more visible contrast for the Scottish shield. The Nova Scotia coat of arms was created on May 28, 1625, but it was not recorded by heraldic authorities in Scotland until the early 19th century, and English heraldic experts were completely ignorant of it. Consequently, a new Nova Scotia shield was granted by Queen Victoria on May 26, 1868.
That new coat of arms, combining a salmon and three thistles, was not popular. On March 7, 1928, an order in council calling for the restoration of the old arms was issued by the lieutenant governor, and a royal warrant was signed on January 19, 1929. It is not entirely clear when the provincial flag of the same design came into existence. There are vague references to its having been flown by Nova Scotia vessels in the 19th century, but it is more likely to have been introduced about 1921, at the time of the publication of a booklet on the Nova Scotia arms and flag. As with many traditional heraldic symbols, there are no meanings attributed to the colours of the Nova Scotia arms and flag.