Smith made his international debut at the 1996 World Curling Championships as the skip for the Scotland team.

His debut was fairly successful, as the team would win the silver medal, losing to Canada's Jeff Stoughton in the final.

The following year Warwick played third for Hammy McMillan and won gold, this time beating Jeff Stoughton's team in the final.

Smith was a member of the Great Britain 2002 Winter Olympics curling team.

[1] At that year's World Championship, Warwick skipped the Scotland team to a bronze medal.