Jason was born and raised in western Sydney where he attended Cabramatta Public School and Canley Vale High School before graduating with a Bachelor of Arts (Honours) and a Bachelor of Laws from the University of New South Wales. Before entering Parliament, he worked as a Senior Adviser to NSW Premier Bob Carr and as an executive at Transurban, one of Australia's top 100 companies.

Jason was elected as the Federal Member for Blaxland in 2007. In June 2009, he was appointed Parliamentary Secretary for Employment. In September 2010, he was appointed Minister for Defence Materiel. In December 2011, he was appointed Minister for Home Affairs and Minister for Justice. Following the 2013 election, Jason was appointed Shadow Minister for Communications. In July 2016, he was appointed Shadow Minister for Trade and Investment as well as Shadow Minister for Resources and Northern Australia. In June 2019, Jason was appointed Shadow Minister for Regional Services, Territories and Local Government and Shadow Minister for Housing and Homelessness.

"Our education system is the most powerful cause for good in this country. Run well, it can ensure that every child has the opportunity to reach their potential. It is the great equaliser in an unequal world. If we are serious about equal opportunity for men and women, for rich and poor, for indigenous and multicultural Australia, then let it begin with the youngest Australians."

He joined the Australian Labor Party because of its commitment to improving the lives of working Australians, particularly through education.

Jason is the Patron of Care Leavers Australia Network (CLAN), the Bankstown Youth Development Service (BYDS), the Bankstown Sports Club and the Bankstown RSL.