[1] After spending the first two years of his career in the little clubs Sokol Komatevo, Olimpik Teteven and Dobrudzha Dobrich, in 1999 Bornosuzov signed a contract with the Champion of Bulgaria for 1998–99 Litex Lovech.

For four years in Litex he earned 106 appearances, scored 18 goals and won the 2001 Bulgarian Cup.

One year later Atanas signed with Russian side Tom Tomsk.

3 months later, on 5 October, his compatriot Kiril Nikolov joined the club.

In February 2009 Bornosuzov returned to Bulgaria and signed with Cherno More Varna.