Before entering politics, Hardcastle worked for almost 20 years as a reporter and editor of the former Tecumseh Tribune. Prior to becoming an MP, Cheryl earned her reputation as an effective, inclusive leader as Tecumseh's Deputy Mayor from 2011-2014, serving on both Tecumseh Council and Essex County Council. She was also a member of the Essex-Windsor Solid Waste Authority Board and the Essex Region Conservation Authority Board. A past member of Pathway to Potential and National Pension Reform Committee, she has worked to reduce poverty in Windsor-Essex County and to help more Canadians retire with dignity. She has organized minor sports programs and tournaments, serving as Direction of the Tecumseh Baseball club and President for the Sun Parlour Female Hockey Association. She is a founding member of the Tecumseh Area Historical Society and is an instructor and author of beginning-level readers for adults. She graduated from the University of Windsor with a bachelor's degree in political science and government and a bachelor's degree in communication and media studies.
Municipal politics
As a deputy mayor of Tecumseh, Hardcastle served as chair of the personnel committee, the arts and cultural advisory committee, the Tecumseh heritage advisory committee, the accessibility committee, War of 1812 commemoration committee, the 38th annual Tecumseh Corn Festival committee and the Tecumseh business improvement association. She served as an Essex County representative on regional authorities:
Windsor-Essex Poverty Reduction Strategy - Pathway to Potential - Currently working on determining living wage in region and Evaluation and Reporting Working Group.
Essex Windsor Solid Waste Authority board member since elected and currently Chairperson of the Technical Review Committee dealing with claims for residential properties affected by the closed Maidstone Landfill, in accordance with Ministry of Environment orders.
Essex Region Conservation Authority board member for two years. In January 2013, she stepped aside to allow another elected representative to have the opportunity to serve on this board, in order to broaden perspectives and strengthen resolve on conservation policies.
Federal politics
During the 42nd Canadian Parliament, NDP Leader Thomas Mulcair appointed Hardcastle to be the party's critic for Sports and Persons with Disabilities. After Mulcair was replaced by Jagmeet Singh, he added "International Human Rights" to her critic duties. Hardcastle introduced one private member bill, C-348, which sought to make Employment and Social Development Canada responsible for providing information and guidance to persons with disabilities on all federal applications for grants, benefits, compensation and any other programs and services, as a means of reducing the administrative burden on applicants. The bill was debated at second reading but defeated with the Liberal Party Majority voting against it. She lobbied the government by introducing private member's motion M-56 Canadian with Disabilities Act, m-55 Convention Against Torture, and M-54 Option Protocol to the Convention on the Rights of Persons with Disabilities. She served a vice-chair of the subcommittee on sports-related concussions, and as vice-chair for the subcommittee on international human rights of the standing committee on foreign affairs and international development. She also served as a member of Canada-United States Inter-Parliamentary Group, Canada-Israel Interparliamentary Group, and Canada Group of the Inter-Parliamentary Union.