VCO may refer to:
Military Veterinary Corps Officer, see Veterinary corps (disambiguation) Viceroy's commissioned officer, British Indian Army role (1885–1947)
Technology Voltage-controlled oscillator, an electronic device Voice Carry Over, a telecommunications relay service Akatsuki (spacecraft), or the Venus Climate Orbiter Virtual Central Office, in Open Platform for NFV network-function virtualization software
Other uses Vegan Camp Out, an annual UK camping festival Voyage Century Online, a nautically themed, free-to-play, massively multiplayer online role-playing game Vice Commodore, an elected yacht club committee member VCO SA, the joint-stock company, and a distributor of Volcano clothing brand