Khlong Toei (also Klong Toey, Thai: คลองเตย, pronounced [kʰlɔ̄ːŋ tɤ̄ːj]) is a district in central Bangkok, long known for its slum.

The area has a history dating back to the ninth century as a port to cities upstream along the Chao Phraya River, such as Pak Nam Phra Pradaeng (Thai: เมืองปากน้ำพระประแดง) (as opposed to the current Phra Pradaeng district) built during the King Phutthayotfa Chulalok period.

In 1947, a large portion of Khlong Toei canal was filled to expand the Rama IV Road surface.

Originally Khlong Toei consisted of six sub-districts, three of which later formed the new Watthana district (announced on 14 October 1997, effective 6 March 1998).

Due to its limited capacity and traffic problems caused by semi-trailer trucks, many of its operations have moved to Laem Chabang Port in Chonburi province since its opening in July 1981.