Desmarais is a common surname in French, associated especially but not exclusively with a powerful business and political family in Canada. It may refer to:
- André Desmarais (1956-), Canadian businessman
- Charles Desmarais, president of the San Francisco Art Institute
- France Chrétien Desmarais, Canadian lawyer and businesswoman, daughter of Jean Chrétien and wife of André Desmarais
- François-Séraphin Régnier-Desmarais (1632-1713), French ecclesiastic, grammarian, diplomat and poet
- James Desmarais (1979-), Canadian professional ice hockey player
- Jean Noël Desmarais (1924 – 1995), Canadian physician, radiologist, and politician and brother of Louis Desmarais
- Lorraine Desmarais (1956-), Canadian jazz pianist and composer
- Louis Desmarais (1923-), member of the Canadian House of Commons from 1979-1984
- Ludger Desmarais, professional ice hockey player from 1926–1939
- Marcel-Marie Desmarais (1908-1994), Quebec writer, preacher and broadcaster
- Odilon Desmarais (1854-1904), Quebec lawyer, judge and politician
- Ovide E. Desmarais (1919–1998), American author of books and detective stories
- Paul Desmarais (1927-), Canadian billionaire and CEO of the Power Corporation of Canada
- Paul Desmarais, Jr. (1954-), Canadian businessman, son of Paul Desmarais, and chairman of Power Corporation of Canada
- Pierre DesMarais, Canadian politician and Chairman of Montreal's Executive Committee 1954-1957
It may also be a place name:
- Desmarais, Alberta