Kapoor was commissioned into the Regiment of Artillery on 11 June 1967. He is an alumnus of Sainik School, Kunjpura, National Defence Academy Khadakwasla (30th Course) and Indian Military Academy, Dehradun. His career in the Indian Army spans four decades, during which he has held varied command and as well as staff appointments. A veteran of the 1971 Indo-Pak War in the eastern theatre (Bangladesh), he is an alumnus of the Defence Services Staff College in Wellington and has completed the Higher Command Course at Army War College, Mhow and the National Defence College course at the National Defence College in New Delhi. He served as the Chief Operations Officer for UNOSOM II (United Nations Operation in Somalia II) during 1994-95 and was awarded the Vishisht Seva Medal in January 1996.