He began his notable collaboration with director Peter Weir on the 1982 film The Year of Living Dangerously, on which he was an associate editor working with Weir's longtime editor William M. Anderson. He was credited as a co-editor with Anderson for Fearless (1993) and for The Truman Show (1998). He was the sole editor for Weir's Master and Commander: The Far Side of the World (2003), for which Smith was nominated for the Academy Award for Film Editing and for an "Eddie Award" from the American Cinema Editors.
More recently, Smith has edited four films with director Christopher Nolan. He was nominated for a second Academy Award and American Cinema Editors Award for The Dark Knight (2008).