Wilhelmsen is a surname. Notable people with the surname include:
Arne Wilhelmsen (born 1929), Norwegian businessmanFabian Wilhelmsen (born 1986), German footballerFrederick Wilhelmsen (1923–1996), American philosopher and professor in the Thomist traditionLars Wilhelmsen (born 1946), Norwegian civil servantThorvald Wilhelmsen (1912–1996), Norwegian long-distance runner, specialized in the 10,000 metresTom Wilhelmsen (born 1983), Major League Baseball relief pitcher for the Seattle MarinersUnni Wilhelmsen (born 1971), Norwegian singer, songwriter and musician