Cianjur (Sundanese: ᮎᮤᮃᮔ᮪ᮏᮥᮁ) is a town and district in the West Java province of Indonesia, and is the seat of Cianjur Regency. The district of Cianjur is located along one of the main roads between Jakarta (120 km to the northwest) and Bandung (60 km to the east). The population was 158,125 at the 2010 Census and 173,265 at the 2020 Census; the official estimate as at 2025 was 178,798. Because of its location, some of Cianjur's residents commute to work in Bandung.

The road on which Cianjur is located used to be the main (extremely busy) road from Jakarta to Bandung but was in effect replaced as the main road link between these two main cities when the Jakarta-Bandung tollroad was fully completed in 2005. However, due to its low traffic, Cianjur returned as one of the alternative routes for travellers from Jakarta and Bandung.

Cianjur was founded in 1677, with the first head of the town being R. A. Wiratanudatar I, entitled Dalem Cikundul, as the descendant from the old Sundanese city of Pajajaran.

By 2007 the city government asked female municipal employees to wear jilbab (hijab). It also placed road signs encouraging women to wear jilbab.

A magnitude 7.0 earthquake struck offshore West Java on September 2, 2009, killing 21 people in Cianjur alone.

Another 5.6 magnitude earthquake occurred on November 21, 2022, killing 331 and injuring 7,729 others.

Cianjur District is divided into eleven administrative villages which are as follows, with their areas and populations as officially estimated at mid 2024, together with their post codes:

Pamoyanan, Sawahgede, Bojongherang, Sayang, Solokpandan and Muka are formally classed as urban kelurahan, while the other five villages are rated as rural desa.