Stelmakh competed at the 2020 European Championships held in Mersin, Turkey.

[1][2] Stelmakh competed at the Euro Youth Olympic Festival, where he won the individual All-Around.

[3] Additionally he won the bronze in the mixed pair event together with Anna Lashchevska.

He also won silver on floor and pommel horse and a bronze medal on parallel bars.

Stelmakh competed at the 2024 European Championships alongside Nazar Chepurnyi, Illia Kovtun, Igor Radivilov, and Oleg Verniaiev where he helped the Ukrainian Team to Team gold.