Career
Pirin Blagoevgrad
Born in Blagoevgrad, Kostov began his career at Pirin 2001 as an important part of their youth team In January 2010 he was scouted by Pirin Blagoevgrad. Kostov netted his first goal as he scored the winning strike in a 2–1 home victory over Lokomotiv Sofia on 11 September.
On 25 September 2010, in a home match versus Minyor Pernik, Stanislav scored the only goal for Pirin in a 1–1 draw.
On 16 October he assisted Boris Kondev for the opening goal in a match against Levski Sofia, but Pirin went on to lose the game 4–1. CSKA Sofia
After a good first half of the season with Pirin, Kostov caught the eye of the major Bulgarian clubs CSKA Sofia and Levski Sofia.
After a tough transfer battle for the youngster, Kostov finally decided to sign with CSKA. He made 21 appearances for CSKA, scoring 3 goals. Botev Plovdiv
On 22 June 2012, Botev Plovdiv signed Kostov on a season-long loan deal, with the option of making the move permanent.
On 10 August, Botev exercised the option to buy 100% of Kostov"s contract.
He signed a two-year contract.
