On 30 March 2004, Chhetri played his first game for the Indian U-20 team in the 1–0 victory over Pakistan U-23 team in the 2004 SAF Games in Pakistan. On 3 April 2004, Chhetri scored twice for the Indian U-20 team against Bhutan U-23 team in their 4–1 victory. On 12 June 2005 Sunil scored his first goal for the senior India national football team against Pakistan.