[2] After staying for two years with Romanian side Oțelul Galați, Kolev signed a two-and-a-half-year contract with Chernomorets Burgas on 24 February 2010, moving on a free transfer.

After being named on the bench for Chernomorets's eleven games of the 2009–10 season, Kolev finally made his debut at home against Slavia Sofia on 2 May in a 2–2 league draw.

In July 2015, several months later, after CSKA Sofia was sent to the third division due to the bad financial situation in the team, Kolev came out of retirement and went back on the field.

He made his debut for Plamen Markov's Bulgaria in a friendly against Spain on 20 November 2002, when he was a CSKA Sofia player, coming on as a second-half substitute during 0–1 defeat at Los Cármenes in Granada.

[6] Kolev was Bulgaria's third-choice goalkeeper, behind Zdravko Zdravkov and Dimitar Ivankov, at the UEFA Euro 2004, remaining an unused substitute in the tournament.