A graduate of the University of New Brunswick, John Harrington began his professional career in 1986 with Coffin & Richardson as a Site Engineer. He continued his career with Church Engineering Inc. where he obtained his Professional Engineer's License.

In 1990, he joined Flatiron Construction, first as a project engineer on major highway projects, then managing all of Flatiron's Southern California operations. 

In 2004, he became Vice President and General Manager of Atkinson Construction.

In 2015, John Harrigton was appointed Executive Vice President of Operations for Colas USA, where he manages and directs the Sully-Miller, Simon and Colaska subsidiaries, as well as Colas Construction USA Inc, the major projects company created by Colas USA. In March 2022, he was promoted to Executive Vice President, United States.