Mikkel (Michael) T. Lillehaugen was born June 4, 1881, in Ål, Buskerud, Norway. At the age of four, he emigrated with his parents, Tosten Mikkelsen and Sigrid Larsdatter. The family lived in Dodge County, Minnesota, for three years and then, in 1888, settled in Perth Township, Walsh County, North Dakota. Michael Lillehaugen married Helen Sando in 1907. She died in 1914 leaving her husband with three small children. In 1915, Lillehaugen married Marie Moe. They had six children.

Lillehaugen was active in church, civic, and community affairs. He served as church secretary for Sarnia Lutheran Church for 36 years and was instrumental in establishing the Michigan Telephone Company. He also helped establish the Livestock Shipping Association in Whitman and served many years on the board of directors of the Whitman elevator.

A Republican, Lillehaugen was first elected to the North Dakota House in 1926, serving one term. He was elected again to the House in 1932, serving another term. In 1940, he was again elected and served seven consecutive terms. In 1952, Lillehaugen was a delegate to the Republican National Convention in Chicago.

Lillehaugen died October 24, 1972, in Michigan, North Dakota. He is buried at West Forest Cemetery.