CSU may refer to:
- Channel service unit, a Wide area network equivalent of a network interface card
- Chari Aviation Services, Chad, by ICAO airline code
- Christian Social Union (UK), an Anglican social gospel organisation
- Christian Social Union in Bavaria, a political party in Bavaria, Germany
- Civil Service Union, a defunct trade union in the United Kingdom
- Constant speed unit, a mechanical device on an aircraft propeller that regulates engine speed by automatically changing pitch
- Crime Scene Unit, a forensic in some police groups this refers to crime scene investigators who respond to a crime scene
- Český statistický úřad, Czech Statistical Office
