Khlong Toei (also Klong Toey, Thai: คลองเตย; IPA: [kʰlɔ̄ːŋ tɤ̄ːj]) is a district in central Bangkok, long known for its slum. It is bordered by the Chao Phraya River and contains major port facilities. It is also the name of a major market, though not touristic. The market is served by the Bangkok Metro station Khlong Toei on Rama IV Road.

Neighboring districts are (from the north clockwise) Watthana, Phra Khanong, across the Chao Phraya the district Phra Pradaeng of Samut Prakan, Yan Nawa, Sathon and Pathum Wan.

The district was once part of Phra Khanong. It was later separated into a new district on 9 November, 1989. Originally Khlong Toei consisted of 6 sub-districts. Three of which have since left to form the new Watthana district (announced on 14 October, 1997, effective from 6 March, 1998).

The area has a history dated back to the ninth century as a port to cities upstream along Chao Phraya River. It was a city called Pak Nam Phra Pradaeng (Thai: เมืองปากน้ำพระประแดง) as oppose to the current Amphoe Phra Pradaeng built during King Buddha Yodfa Chulaloke period. Khlong Thanon Trong (Thai: คลองถนนตรง) was a khlong (canal) and a parallel road built by King Mongkut around 1857. Later, it became known as Khlong Toei and Khlong Hua Lamphong for different sections of the canal. Khlong Toei means the canal of pandan as the plant grew along the southern bank of the canal. The road was renamed to Rama IV Road by King Vajiravudh in 1919. In 1947, a large portion of Khlong Toei canal was filled up to expand the Rama IV Road surface.