Cockbain played over 60 tests for the national team, the Wallabies including winning the 1999 Rugby World Cup. He made his debut for Australia in 1997 in Brisbane, in a Test match against France. He played for the Queensland Reds, a short stint with the Cardiff Blues, World Corporation in Japan and for the Melbourne Rebels (ARC) franchise in the now defunct Australian Rugby Championship provincial competition in 2007. He was called up as an injury standby for the 2007 Wallaby World Cup squad. His brother, Brent Cockbain played rugby union for Wales.