Barrett made his debut for the Jamaica national football team in 1990 against Barbados. He captained his nation at the 1998 FIFA World Cup. According to the Jamaica Football Federation, Barrett earned 127 caps for his country, but this figure has not been officially acknowledged by FIFA because the JFF includes all matches, even against club sides, youth or olympic teams. He played his final FIFA international in 2000 against Honduras in the 2000 CONCACAF Gold Cup; he came on as a substitute for midfielder Winston Griffiths as Aaron Lawrence was sent off. He is married with three children, Ashley, Warren Jr. and Moya.