He was a member of parliament between 1996 and 2002, representing the Alliance Party, has held a number of seats in local government.
In the 2002 election, Gillon was ranked third on the Progressive Coalition list, behind Jim Anderton and Matt Robson.
[citation needed] Gillon has also worked as a dairy farmer, senior fire officer, and an entrepreneur in light manufacturing, printing, educational resource and publishing.
[citation needed] His daughter, Paula, is also active in Auckland local body politics; having been elected in 2001 to the North Shore City Council two weeks after reaching the required age of eighteen.
Grant Gillon's eldest son, John, serves as Chair of the Kaipatiki Local Board.
[14] Along with Marilyn Waring, he supervised former minister George Gair's master's thesis at Auckland University of Technology in 2010.