[4] Sunil was born on 6 May 1989 to Vittalacharya and Shanta in the Kodagu district of Karnataka, is a Vishwakarma Brahmin and is an ethnic Kannadiga.

In 2005, he was drafted into the Indian Army Service Corps as a havildar, where he shone as a player in the inter-services league.

[7] Sunil made his senior international debut in 2007 during the Asia Cup in Chennai, a tournament that India went on to win.

[8] India defeated South Korea in the final of the tournament by a 7–2 margin, with Sunil scoring the second goal for his team.

[16] He won bronze with India in the Sultan Azlan Shah Cup a few prior scoring two goals in the tournament.

[18] In the auction of the Hockey India League in 2013, Sunil was bought by the Punjab franchise for US$42,000[19] with his base price being US$13,900.

[3] He was a regular member of the India squad until he was first dropped for his team's Argentina leg of the 2020–21 season of Pro League.

[23] However, he came back from retirement a few months later and was included in India 'A' core probables, picked up to train a developmental group for the senior national team.