Between 1982 and 1990, he assumed different positions in the Ministry of Internal Affairs as a firefighter and later as a professor at the Police Academy in Sofia. As a National Security Office member, Borisov took part in the protection of crops and haylofts during the name-changing campaign towards ethnic Turks in the 1980s. He quit the Ministry in 1990. In 1991 he founded a private security company, Ipon-1, and later guarded personalities like Todor Zhivkov and Simeon II. Borisov has been actively participating in karate championships since 1978, serving as the coach of the Bulgarian national team and a referee of international matches. He currently has a 7th dan black belt in karate and is the chairman of the Bulgarian Karate Federation. Borisov has also been a coach for the Bulgarian national karate team for many years.