He graduated with his bachelor's degree in political science and then attended the Fredric G. Levin College of Law at the University of Florida, receiving his Juris Doctor in 1990.

[2] Upon leaving the City Council, he was appointed by then-Governor Charlie Crist to the Tampa Bay Area Regional Transportation Authority, a position that he held from 2007 to 2010.

In 2010, incumbent State Representative Ed Homan was unable to seek re-election due to term limits, so Harrison ran to succeed him in the 60th District, which stretched from Lake Magdalene to Thonotosassa and Mango.

In the general election, he faced Russ Patterson, the Democratic nominee and a retired United States Air Force officer.

He won the Republican primary unopposed and faced Mark Danish, a middle school science teacher and the Democratic nominee, in the general election.