Smith played minor pro with Ottawa-Hull for several years but then created a controversy in 1963 when he refused to report to Springfield of the AHL after the Montreal Canadiens traded his rights. The result was Smith being suspended for the entire 1963-64 season.

Realizing he had few options from which to choose, Smith reported to Springfield where he played for three years. In 1967 the NHL expanded by six teams which is when the Los Angeles Kings acquired the Springfield franchise. The Kings needed to fill their roster heading into their first season and Smith made the grade, appearing in 58 games, scoring ten goals and 19 points.

Smith was traded to Montreal in the summer of 1968, but never played a game for the Habs, being traded again in November to the Minnesota North Stars where he played nine games to round out his NHL career. He was out of hockey for two years but made a comeback in 1972-73 with the start of the WHA. Smith signed a contract with the Houston Aeros and played in 48 games, retiring at the end of the year at the age of 32. Smith's father Des Smith played with Montreal, Chicago and Boston in the late 1930s and early 1940s while younger brother Gary Suitcase Smith tended goal for seven NHL teams during a pro career that spanned from 1965 to 1980.

Smith's life came to a tragic end when he was murdered by a deranged man who had previously been diagnosed with a mental illness but had refused psychiatric treatment. The killer, who had an immense dislike for the media, randomly selected Smith as his victim, fatally shooting him while on his way to work as a sportscaster at an Ottawa television station on August 1st, 1995. He was 55. An inquest into Smith's killing recommended there should be more public protection and significant changes to the Mental Health Act in Ontario. The end result, Brian's Law, was passed on June 21, 2000 by the Ontario Legislature.