Johnson established a public policy and communications firm, Janis Johnson & Associates, in Winnipeg. Johnson was the first woman to serve as the national director of the Progressive Conservative Party of Canada in September 1983. She returned to Manitoba in 1985 and established JJ & Associates, a government relations and communications firm. In 1989 she joined Peat Marwick Public Affairs. She also served on the Canadian National Railwaysboard of directors from 1985-1990. Johnson worked as a freelance consultant in public affairs and also as a lecturer in the Faculty of Continuing Education at the University of Manitoba. She set up the first Progressive ConservativeWomen's Caucus of Winnipeg and co-directed the Mulroney Leadership Campaign in 1983. She also was active in the volunteer sector, serving on the inaugural board of Manitoba Special Olympics, the University of Winnipeg board of directors, the board of directors of Prairie Theatre Exchange and the Winnipeg Art Gallery.
Senate career
Johnson was appointed to represent the province of Manitoba in the Senate by Prime MinisterBrian Mulroney in 1990. She was a senior member of the Standing Senate Committee on Foreign Affairs and International Trade, the Senate Committee on Energy, the Environment and Natural Resources and Senate Chair of the Canada-United States Inter-Parliamentary Group. Johnson's first speech in the Senate was about the Mulroney government's anti-abortion bill, which she voted against. In 2014, Johnson became the Honorary Chair of Nature Canada’s Women for Nature Initiative. In 2015, Johnson was named among 30 senators in an audit of Senate expenses. She criticized the report, but later repaid the $22,706 it said she owed in questionable travel expenses, maintaining that they were legitimate and the report was incorrect. Johnson retired from the Senate on September 27, 2016, exactly twenty six years after she was appointed. She was the longest-serving Conservative member of the Senate and Manitoba's longest serving senator.
Johnson is the recipient of many honours, including the Queen's Jubilee Medals, the Canada 125 Medal, the Special Olympics Award for Volunteerism, the Outstanding Alumni Award from the University of Manitoba. In 2000, she was awarded the Order of the Falcon Award from the Government of Iceland for her efforts in promoting Canada-Iceland relations.