伊斯坦布尔体育AS 21岁以下

İstanbulspor was founded by Kemal Halim Gürgen, also known by his native Albanian name of Qemal Omari and Istanbul Boys High School students. It was founded on 4 January 1926, being one of the first sports clubs of the Turkish Republican period. In the 1931–32 season, İstanbulspor won both the Istanbul League and Turkish Football Championship.

Until 1990, the club was managed by the Istanbul High School foundation. During this period, İstanbulspor has been relegated from and promoted to the top division several times. Also, it relegated to the amateur level in 1979 and played at the amateur level for two seasons. In 1984, club was relegated to third league. In 1990, Uzan Holding, led by Turkish businessman Cem Uzan, 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 they reached fourth place in the 1997–98 season and played in the UEFA Cup. Uzan family withdrew its support from İstanbulspor in 2001. Because of this, İstanbulspor fell into financial crisis and came ninth in the 2002–03 season.

Eventually, in 2003, the Turkish government took over the financially collapsed club. However, Istanbulspor were relegated to the second league in 2004–05. In 2006, İstanbulspor were resold by the 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 to avoid relegation at the last two seasons. İstanbulspor escaped from relegation in the 2008–09 season after finishing sixth in the Third Group. However, İstanbulspor finished the second group of the 2nd League next season as second from last and were finally relegated to the Third League, which is the fourth level of the Turkish football system. They played in the promotion play-offs in the 2012–13 and 2013–14 seasons but failed to achieve success. İstanbulspor finally promoted to the Second League after defeating Zonguldak Kömürspor and Çorum Belediyespor successively in promotion play-offs in the 2014–15 season.