As an amateur, Todorov won the world championships three times, in 1991 at bantamweight, and in 1993 and 1995 at featherweight. He won a silver medal at bantamweight in 1989m, losing to Cuban Enrique Carrion in the final. He also won the European amateur championships in 1989 and 1991 at bantamweight, and in 1993 at featherweight.
Todorov represented Bulgaria at the 1992 and 1996 Olympic Games. In 1992 he lost in the quarter-finals to North Korean Li Gwang-Sik. In 1996 he qualified to the semi-finals where he met the then 19 year-old American, Floyd Mayweather, Jr. Though most observers felt that Mayweather won the fight, the victory was awarded to Todorov by a narrow 10–9 points margin. Even the referee seemed to be somewhat surprised because he initially raised Mayweather's hand at the end of the fight. The United States team protested the result but with no success. Todorov went on to the final where he lost to Somluck Kamsing from Thailand and settled for the silver medal.