Mesley began her broadcast journalism career in 1976 as a radio reporter in Toronto. Mesley moved to television in 1979, first with CTV's CFCF in Montreal, then moving to CBC-TV as a legislative reporter for local news and The National, based in Quebec City. During this six-year period she covered the first referendum on sovereignty and some of the most fascinating politicians of our times, such as Jean Drapeau, Robert Bourassa, Jacques Parizeau, Rene Levesque and Pierre Trudeau.
In 1985, Mesley moved to Ottawa as a parliamentary correspondent for CBC-TV's The National. During this intensely political time, Mesley reported on such stories as the battles over free trade, the GST and Meech Lake.
In addition, she was a frequent contributor to CBC Television's Sunday Report panel, and soon after became Sunday Report's anchor.
In 1994, Mesley helped create and hosted CBC Television's Gemini Award-winning Undercurrents, a program that examined the media/marketing world. Lasting six seasons, Undercurrents was relevant, intelligent, fast-paced and fearless--a weekly journalistic program that brought the traditional hard reporting of a current affairs show to media culture. More recently, she co-hosted Marketplace, CBC Television's award-winning prime-time investigative consumer show, and CBC Television's Test The Nation.
Mesley has won three Gemini Awards for her work on Marketplace and Undercurrents. Undercurrents also won a Gemini for Best Information Program and garnered a Gold Medal for Best Magazine Format at the New York Festival's International Television Awards. Mesley was honoured in 2006 with the John Drainie Award, for her contribution to Canadian broadcasting.