After graduating she worked for the federal government as a spokesperson for Bob Kaplan[1] and also as a press liaison office for Stuart Smith, leader of the Ontario Liberal Party.
[3] In 1984, she worked for Lowther Consulting, a company owned by Jim Coutts who was a principal secretary for Prime Minister Pierre Trudeau.
In 1988 Guarnieri was nominated in the new riding of Mississauga East after a fractious contest with another candidate, Armindo Silva.
The party hired police officers to control the crowd due to threats made against Guarnieri.
[7] Guarnieri was elected as Member of Parliament in 1988 in a fairly close race with her Progressive Conservative opponent Laurie Pallett.