Madsen is the grandson of Ezra Taft Benson, Secretary of Agriculture under President Eisenhower.

[2] In 1994, Mark met Erin Michele Allen, an Idaho native, working in Washington, D.C.

[2] In March 2000, Madsen was elected as the first resident president of the North Ranch Homeowners Association.

He then went on to work for lobbying organizations promoting Ronald Reagan's Strategic Defense Initiative and a federal Balanced Budget Amendment.

[2] Madsen is affiliated with the Federalist Society and the American Leadership Academy in Spanish Fork.

[7] In July 2016, Madsen switched from the Republican to the Libertarian Party and endorsed Gary Johnson for president.

[8] [9] In the 2008 session of the state legislature, Madsen was chief sponsor of SB 210,[10] a bill that required proof of citizenship to be presented in order for Utahns to register to vote.

247S03,[14] which passed both houses of the Utah Legislature and was signed into law, recognized John M. Browning on January 24, 2011.

[13] In 2015, Senator Madsen introduced a medical marijuana bill, S.B.259, which failed because the legislature wanted to study the issue further during the interim before acting.

During the session his difficulties increased when the Church of Jesus Christ of Latter-Day Saints said it opposed his bill.