"OPO" or "Opo" can refer to:
- Optical parametric oscillator
- OPO is the IATA airport code of Francisco de Sá Carneiro Airport, Porto, Portugal
- Organ procurement organization, which helps to arrange organ donation
- One Person Operation, a term used in road passenger transport where a driver of a vehicle has sole responsibility for operating the vehicle and passenger interaction. The opposite of the earlier two-person operation system where the vehicle operation and passenger interaction roles (for example, driver and conductor) were separate and distinct.
- Opo is a common name for the squash species Lagenaria siceraria
- Opo the Dolphin was the name of a famous dolphin in New Zealand
- Online Presence Ontology
- Orlando Philharmonic Orchestra
- Ovamboland People's Organization the predecessor of SWAPO