Beauharnois may refer to:

• An alternative spelling of French House of Beauharnais

• Charles de la Boische, Marquis de Beauharnois (1670–1749), Governor General of North-American New France (fr: Nouvelle-France); places carrying his name, including: Beauharnois, Quebec and Fort Beauharnois, Minnesota
• Claude de Beauharnois de Beaumont et de Villechauve (1674–1738), French naval officer
• François de Beauharnois de la Chaussaye, Baron de Beauville (1660s–1746), French naval and colonial administrator in France and in New France (Nouvelle-France)

• Beauharnois (federal electoral district)
• Beauharnois (Province of Canada electoral district)
• Beauharnois (provincial electoral district)
• Beauharnois, Quebec
• Beauharnois Canal
• Fort Beauharnois
• Beauharnois—Laprairie
• Beauharnois—Salaberry
• Beauharnois-Salaberry Regional County Municipality, Quebec

• Battle of Beauharnois
• Beauharnois scandal
• HMCS Beauharnois (K540) - Canadian Flower-class corvette
• BHS, an OVH datacenter in the city of Beauharnois, south of Montreal, Canada
• Beauharnois Hydroelectric Power Station

• Fort Beauharnois, Minnesota