Hislop was a youth international for Trinidad and Tobago. He had played in three games for Trinidad and Tobago before 1989. In 1992, he was called up to the Trinidad national football team but was an unused substitute in three games. In May 1995, he said that he would prefer to play for England as he was born and raised there and the standard of competition was higher. He was called up for England against Chile at Wembley Stadium in February 1998. A month later, at the age of 26, he was one of three over-age players selected to play for the England U-21 side against Switzerland. Hislop played a total of 26 times for the Twin Island nation, also captaining the team in 5 matches. Hislop had announced his retirement from international football in 2004, citing the long journeys between England and the Caribbean as a factor, but returned to the national team to aid them in the 2006 FIFA World Cup Qualifiers at the request of the Trinidad and Tobago national team management. In 2005, he was part of the Trinidad and Tobago side that qualified for the 2006 World Cup with a victory over Bahrain. The draw for the World Cup placed them in Group 2 alongside Sweden, Paraguay and England. On 10 June 2006, Hislop played in the Trinidad and Tobago national team’s first ever World Cup match, in the 0–0 draw against Sweden, replacing Kelvin Jack who suffered a calf injury in the warm-up. Writing in The Times, he would call the occasion ‘the proudest day of his career’.