In 1922 he joined a Kharkiv football team of the Society of Sports Amateurs (OLS).

Next year Kostyantyn joined another Kharkiv team "Physical Culture Club" (KFK), for which he played next three seasons.

In his interview Kostyantyn indicated that during 1928 season Dynamo Kharkiv did not have own head coach and that role was performed by the team's captain.

Soon after capital of Ukraine was moved from Kharkiv to Kyiv, Kostyantyn also moved to Dynamo Kyiv in 1935, with which in 1936 started to play in the newly formed Soviet professional championship in Group A (top tier, a progenitor of the Soviet Top League).

[1] In 1959-64 Kostyantyn Fomin worked as an inspector and a senior methodical adviser at the Tsentralny Stadion imeni V.I.Lenina (Luzhniki Stadium).