Born in Dehradun, Uttarakhand, he started his schooling at St. Joseph's Academy and also played football for his school team. Thapa’s debut in the Hero ISL came in 2016 in a 5-4 thriller which Chennaiyin FC lost. Due to the experienced Bikramjit Singh and Dhanapal Ganesh at the helm in central midfield for Chennaiyin in 2017-18, Thapa’s 16 appearances were mainly restricted off the bench. However, his most important contribution came in the first leg of the semi-final against FC Goa, where he scored a vital away goal. He has also been a vital cog for India since his debut against St Kitts & Nevis and had started all four matches for India in the Hero Intercontinental Cup 2018.