[1] Mullin is a graduate of Castleton State College, where he received a Bachelor of Science degree in business with a major in finance.
[1] Mullin has been involved in several business ventures, including real estate development, management and ownership of movie theaters, and owner of Vermont Roots, a distributor of New England-made food products.
[3] He is the chief executive officer of Glenwood Movieplex Corporation, an independent movie theater chain which has locations throughout the northeast United States.
[1] In January 2003, Mullin was appointed to fill the Vermont Senate seat left vacant when John Crowley resigned to become head of the state Department of Banking, Insurance, Securities, and Health Care Administration.
[1] In May 2017, Mullin indicated his intention to resign after Governor Phil Scott appointed him as chairman of the Green Mountain Care Board.