VO can refer to:
- Austrian Arrows' IATA code
- Data transfer object, formerly known as Value Object
- Seagram's VO Whiskey
- Vanadium(II) oxide, an inorganic compound
- Velocity obstacle
- Virtual organization (disambiguation)
- Visual Objects, an object-oriented computer programming language
- Voice-over
- Virtual Observatory, in astronomy
- Vendetta Online, a computer game
- Volapük language (ISO 639-1 code)
- Vote ordering, a concurrency control technique for guaranteeing global serializability; a generalization of commitment ordering
- Vò, a commune in the province of Padua in northern Italy
- Võ, a common Vietnamese surname
- Vo, Togo, a prefecture in Togo
- Vanguard Mid-Cap ETF, an exchange-traded fund with ticker symbol VO