CTO may refer to:
- Cancelled-to-order, a postage-stamp cancelled by the postal administration before sale to stamp-collectors
- Cape Air Transport, Australia (ICAO airline designator)
- Cape Town Opera, South African opera company
- Caribbean Tourism Organization, a development organization for sustainable tourism for the economic and social benefit of Caribbean people
- Central Treaty Organization, a former intergovernmental military alliance
- Certified Television Operator, an operator certified by the Society of Broadcast Engineers
- Chief technology officer, an executive-level position in a company or other entity whose occupant is focused on scientific and technological issues within an organization
- Commonwealth Telecommunications Organisation, an international development partnership between Commonwealth and non-Commonwealth governments, business and civil society organisations
- Community treatment order, an implementation of mental-health law in Australia and in England
- Configure-to-order, in business, the ability of a user to configure a product before ordering
- Control Tower Operator, an aviation term for certain personnel working in a control tower
- Cyprus Tourism Organisation, a semi-governmental organisation in Cyprus