The island was originally settled by Passamaquoddy Indians who called the place Ebaghuit. Its first European explorers were the French who named it Port aux Coquilles ('Shell Harbor'). Following the War of the Spanish Succession, under terms of the Treaty of Utrecht (1713), the island came under English control.
In 1770, a grant of the island was made to Captain William Owen (1737-1778) of the Royal Navy who renamed it Campobello. The name was taken from that of the Governor of the Province of New Brunswick, Lord William Campbell, and mixed with bello from the French, Spanish and Italian origins of the word "beautiful". By the end of the 18th century, the small island had a thriving community and economy and by the mid 1800's it had a population in excess of 1,000 persons. In 1866, a Fenian Brotherhood war party of 700+ members arrived at the Maine shore with the intention of seizing the island from the Canadians. The United States government stepped in and a military force dispersed the marauders. This action served to reinforce the idea of protection for New Brunswick by joining with Nova Scotia, Quebec, and Ontario to form the proposed Dominion of Canada.
Always a community that relied heavily on fishing as the mainstay of its economy, following the acquisition of the island by private American investors, in the 1880's a luxurious hotel was built and the island became a popular summer resort for wealthy Canadians and Americans, many of whom built grand estates there. Included in this group was Sara Delano and her husband James Roosevelt Sr from New York. Sara Delano had a number of Delano cousins living in Maine and Campobello offered a beautiful summer retreat where family could easily visit. From 1883 on, the Roosevelt family made the Island their summer home. Their son, Franklin Delano Roosevelt, President of the United States, would spend his summers there from the age of one until as an adult, he acquired a larger property, a 34 room "cottage", that he would use as a summer retreat until 1936. It was here that Franklin Delano Roosevelt, Jr, a future American statesman himself, was born there as a Canadian citizen in the summer of 1914.
During the 20th century, the island's prosperity from its wealthy visitors declined with the change in lifestyles brought on by a new mobility from automobiles and airplanes. Nonetheless, for President Roosevelt, the tranquility was exactly what he and his family cherished and the property remained in their hands until Eleanor Roosevelt's death in 1962. The Roosevelt Campobello International bridge from the U.S. mainland, built in 1962, brought a tourism revival and when the 2,800 acre Roosevelt Campobello International Park was created in 1964 following a gift of the Roosevelt estate to the Canadian and United States governments, the tourism trade increased substantially.
In 1960, motion-picture producer Dore Schary and director Vincent J. Donehue made the film Sunrise at Campobello, based on Schary's Tony Award winning Broadway play of the same name. Starring Ralph Bellamy as Franklin Delano Roosevelt, the film covered the years 1921 to 1924 at Campobello Island and events leading up to Roosevelt's nomination as the Democratic Party's candidate for President.