İstanbulspor was founded by Kemal Halim Gürgen and Istanbul High School students in 4 January 1926, being one of the first sports clubs of Republican Turkey period. In 1931-1932, İstanbulspor won both Istanbul League and Turkish Cup. Until 1990, the club was managed by Istanbul High School foundation. During this period, İstanbulspor has relegated from and promoted to first league for several times. Also, it relegated to Amateur Level in 1979 and played as amateur for 2 seasons. In 1984, club was relegated to third league. In 1990, Uzan Holding, led by Turkish businessman Cem Uzan, has bought the club and converted it into İstanbulspor A.Ş., İstanbulspor incorporation. After that, Istanbulspor was funded by Uzan Family and promoted back to first league in 1995. Istanbulspor became one of the most successful Turkish football clubs again, as placed in 4th place in 1997-1998 season and played in UEFA Cup. Uzan Family withdrew its support from İstanbulspor in 2001. Because of this, İstanbulspor fell into financial crisis, and became 9th in 2002-2003. Finally, in 2003, government take over the financially collapsed club. However, Istanbulspor was relegated to second league in 2004-2005. In 2006, İstanbulspor has been resold by government to former Turkish player Saffet Sancaklı's Marmara Spor Faaliyetleri San. ve Tic. A.Ş. for $3,250,000. In 2007, Ömer Sarıalioğlu, a Turkish businessman, bought the club from Saffet Sancaklı. İstanbulspor tried escaped from relegation at last 2 seasons. İstanbulspor escaped from relegation in 2008-2009 season after finishing 6th at 3rd Group. However, İstanbulspor finished 2nd Group of 2nd League next season as second from last and was finally relegated to Third League, fourth level of Turkish league. They played promotion play-offs in 2012-13 and 2013-14 seasons but failed. İstanbulspor finally promoted to Second League, third level of Turkish league after defeating Zonguldak Kömürspor and Çorum Belediyespor successively in promotion play-offs in 2014-15 season.
The colours of İstanbulspor are yellow-black, which are the colours of Istanbul High School. Also white is accepted as a third colour, but this is not official. Having represented Turkey in an international competition, İstanbulspor was granted the privilege to use the Turkish flag in its emblem, located on the top left corner. The emblem of Istanbul High School is at the middle.