Wilhelmsen is a surname. Notable people with the surname include:
Arne Wilhelmsen (born 1929), Norwegian businessman
Fabian Wilhelmsen (born 1986), German footballer
Frederick Wilhelmsen (1923–1996), American philosopher and professor in the Thomist tradition
Lars Wilhelmsen (born 1946), Norwegian civil servant
Thorvald Wilhelmsen (1912–1996), Norwegian long-distance runner, specialized in the 10,000 metres
Tom Wilhelmsen (born 1983), Major League Baseball relief pitcher for the Seattle Mariners
Unni Wilhelmsen (born 1971), Norwegian singer, songwriter and musician
