Sejangkung is a district in Sambas Regency, West Kalimantan, Indonesia.

It is located on the western side of the island of Borneo, bordering Galing and Sajingan Besar to the north, Jagoi Babang and Seluas to the east, Subah and Sajad to the south, as well as Sambas and Teluk Keramat to the west.

The district has an average elevation of 17 meters above the sea level.

[2] Sejangkung was established on 20 April 1963, after being split off from the eastern part of Sambas district.

On 17 June 1996, two of its northeastern villages (Kaliau and Sebunga), became part of newly-established Sajingan Besar district.