Sekolah Menengah Kebangsaan Tunku Sulong (SMK Tunku Sulong) is a secondary school located in Jeniang, Kuala Muda District, Kedah, Malaysia.
SMK Tunku Sulong was founded on January 1, 1971, and was named Sekolah Menengah Jeniang (SMJ).
SMJ later received a total of 150 students.
In 1975, SMJ changed the school name to Sekolah Menengah Kebangsaan Tunku Sulong, a name which was taken from Royal King of Kedah, Tengku Ibrahim.
SMK Tunku Sulong has 39 classes, including Form 1 until Form 6, from morning session to the evening session.