Momchil Tzvetanov was part of both the academy and the first team of FC Litex Lovech and he even set a record of being the youngest player of the club ever performed in the professional league. Other clubs to sign him during in his early professional years were PFC Botev Plovdiv, PFC CSKA Sofia, FC Vereya Stara Zagora and PFC Slavia Sofia.
He brought the Bulgarian Cup with Loko to Plovdiv twice - in 2018/19 and 2019/20 campaigns. The second one (2020) made Tsvetanov but the third player in Bulgarian football ever to win six Bulgarian Cups in his career. Moreover, the successful season got wrapped up by winning the Bulgarian Supercup.
On national level Tzvetanov has registered over 30 appearances for the Sub-17 and Sub-21 teams. Two of the most memorable games for him put him in playing against Israel (April 27th 2008) and Hungary (July 19th 2008). His performance earned him a UEFA award for best player of the Hungary match.