He was a long-time aide to former U.S. Sen. Robert Torricelli, serving as Torricelli's Chief of Staff in the U.S. Senate and the U.S. House of Representatives. He also served on the staff of former New Jersey Gov. James Florio.
From 1999 to 2001, Fox served as the Executive Director of the Democratic Senatorial Campaign Committee, while Torricelli was the chairman of the committee. In 2002, Fox was appointed by New Jersey Gov. James McGreevey as the New Jersey Commissioner of Transportation. While serving as Transportation Commissioner, Fox also served as Chairman of the New Jersey Transit Board of Directors.
In 2003, McGreevey appointed Fox as Chief of Staff to the Governor, a position he held until McGreevey's resignation in November 2004. Following McGreevey's resignation, he became Deputy Executive Director of the Port Authority of New York and New Jersey (PANYNJ), where he administered the New York region's three airports, seaports, the PATH commuter train system and the development of the World Trade Center site.
He announced his intention to leave the Port Authority on July 1, 2007, in order to become a private consultant. While serving at the Port Authority, Fox also served as a Commissioner of the New Jersey Local Finance Board.
In September 2008, Fox became a Senior Advisor for the Obama/Biden campaign, working out of the Florida HQ in Tampa. Following the campaign, he returned to Fox and Shuffler.[clarification needed]. During this time he was lobbiest for United Airlines.
Fox is currently under investigation by the Justice Department. His communications have been subpoenaed by federal investigators looking into corruption at the PANYNJ.  Fox, in his capacity as a United Airlines lobbiest, is alleged to have helped arrange the so-called "Chairmans flight" for Port Authority Chairman David Samson.  In September 2015, Foxx accused of violating ethic laws by two former state officials for not recusing himself from a meeting that discussed United Airlines involvement in Atlantic City Airport. He resigned in October 2015.  saying the investigation did not influence the decision.
- Santiago, Katherine. "High-profile political strategist Jamie Fox helps Gov. Corzine's re-election campaign as unpaid adviser". The Star-Ledger. The Star-Ledger. Retrieved 19 January 2011.
- Sullivan, John. "IN PERSON; McGreevey Goes for Muscle", The New York Times, December 1, 2002. Accessed October 23, 2011.
- MELISSA HAYES and CHRISTOPHER MAAG. "Christie nominates two key lobbyists, one a Democrat, to Cabinet jobs". NorthJersey.com.
- "Port Authority inquiry puts N.J. transportation chief in unwanted spotlight".
- "The Dinner Proposal That Led United Into a Corruption Probe". Bloomberg.com. 28 April 2015. Retrieved 3 October 2015.
- "N.J. transportation chief accused of ethics violations, reports say". NJ.com. Retrieved 3 October 2015.
- "Jamie Fox resigns as N.J. Transportation Commissioner". NJ.com. Retrieved 3 October 2015.