Fort Beauharnois (French pronunciation: [fɔʁ boaʁnwa]) was a French fort, serving as a fur trading post and Catholic mission, built on the shores of Lake Pepin, a wide section of the upper Mississippi River, in 1727.

It was the site of the first Roman Catholic chapel in what is now Minnesota, which was dedicated to St. Michael the Archangel.

The fort was named after the Governor of New France at the time, Charles de Beauharnois.

Today, an Ursuline convent and the Villa Maria Conference Center stand on the site of the old fort, in Florence Township of Goodhue County, in the Roman Catholic Archdiocese of Saint Paul and Minneapolis.

The Minnesota Department of Transportation inventories a roadside historical marker of the presumed location of the fort along US 61/US 63.