Easton was born in Montréal, Québec, Canada, the son of Mary Louise (née Withington) and Leonard Idell Easton, a civil engineer. He started acting in a children's theatre group before moving, at the age of seventeen, to Ottawa to work in a weekly repertory theater.
Easton underwent a procedure to correct a heart arrhythmia in 2006, briefly delaying the opening of Tom Stoppard's The Coast of Utopia, in which he plays a central role. In 2002, Easton starred in the title role in a multi-part documentary, Benjamin Franklin, on PBS. Between 2005 and 2011, Easton appeared as Benjamin Franklin in a series of commercials and videos about Freemasonry, produced for the Grand Lodge of Massachusetts A.F. & A.M.