With the retirement of Lloyd Robertson of CTV National News on September 1, 2011, Mansbridge became the longest-serving active anchor among the big three networks in Canada, as Dawna Friesen had taken over as anchor at Global National only in 2010.
Mansbridge has won several honours throughout his career, including 12 Gemini awards; in 2008, he was made an Officer of the Order of Canada, the second grade of nation's second highest civilian honour.
In 1975, Mansbridge became a reporter in Saskatchewan for the CBC's flagship evening news program The National; in 1976, he relocated to Ottawa to become parliamentary correspondent.
Following a decade of political coverage, Mansbridge had become a substitute anchor for Knowlton Nash and in 1988, CBS offered him a job as a co-anchor for a morning show.
He was on the air live when the 2003 invasion of Iraq began and anchored coverage of it, on the scene, he anchored coverage of the fall of the Berlin Wall, the funerals of Diana, Princess of Wales and Pope John Paul II, numerous royal, papal, and US presidential visits to Canada, numerous Olympic Games, and the inauguration of US President Barack Obama.
He reported extensively from Normandy both 50 and then 60 years after D-Day and from the United Kingdom and the Netherlands for the fiftieth anniversary of V-E Day.