Founded in 1926 by the English Benedictines, the school is located on a 525-acre campus in Portsmouth, along Rhode Island's Narragansett Bay.

The land was later owned by the Anthony family, and in 1778 it was the site of the Battle of Rhode Island during the American Revolution.

In 1864, Amos Smith, a Providence financier, built what is now known as the Manor House and created a gentleman's farm on the site with the help of architect Richard Upjohn.

After buying the Manor House and surrounding land in 1918, Dom Leonard Sargent of Boston, a convert from the Episcopal Church, founded Portsmouth Priory on October 18, 1918.

The Abbey's Church of St. Gregory the Great contains a wire sculpture titled Trinity, created by the late American sculptor Richard Lippold in 1960.