Kean took his seat in the Assembly on October 28, 2002 following his selection by the District 11 Republican County Committee members to fill the vacancy created by the death of Assemblyman Thomas S. Smith. The Assemblyman served as an aide to Senator John O. Bennett from 1994 through 1996.
In the Assembly, he was the Assistant Republican Whip from 2004 to 2008. Kean served in the Assembly on the State Government Committee and the Transportation and Public Works Committee.
Kean grew up in Deal and attended Red Bank Catholic High School. Kean received a B.A. in 1988 from Seton Hall University in Political Science, was granted an M.A.L.S. in 1992 from Columbia University in American Studies and was awarded a J.D. from the Seton Hall University School of Law in 1995. He was born in Montclair, and resides in Wall Township.
Kean writes a column titled "Legislative Matters" in The Coast Star, a weekly local newspaper in Monmouth County. His column typically contains news from the statehouse in Trenton, opinions on issues facing his district, and criticism of the currently governing Democratic Party.