Sergey Alayev started his career with
Yunist Chernihiv. In 1999 he moved to the main club of
Chernihiv, where he played 2 matcthes. Here he stayed until 2004 playing 47 matches and scoring 11 goal. In summer 2004 he moved to Polesie Dobryanka without playing and he returned to
Desna Chernihiv. In the season
2005–06 he won the
Ukrainian Second League. In 2007 he moved to
Hirnyk-Sport Horishni Plavni and in summer 2008 he moved to
Stal Kamianske. Then he returned to
Desna Chernihiv where he played 17 matches and scoring 4 goals. In 2010 he moved back to
Desna Chernihiv. In 2013 he played 6 matches
LKT-Slavutich Slavutich and in 2015 he moved to
Avanhard Koryukivka playing 35 matches and scoring 5 goals. ==Honours==