Before entering politics, Cummins worked in the pulp and paper industry in Ontario, the oil fields of Alberta and on the construction of the Bennett hydroelectric dam in Northern BC.

He taught school in the Northwest Territories and in the Peace River district of Northern Alberta, then spent fifteen years teaching in Delta, British Columbia.

As a Member of Parliament, Cummins served twice as party critic for Fisheries and Oceans, in addition to his work on various other House of Commons and Joint Committees.

On October 19, 2010, Bill Tieleman wrote about John Cummins convention speech where Tieleman writes that "the BC Conservatives are going to target not only disgruntled BC Liberal voters but also the NDP's traditional support bases".

[6] He issued an apology a couple days later, saying "My comments on CFAX radio this past Wednesday may have been misinterpreted and may have offended some.