| Acronym | Definition |
|---|
| CIO | Chief Information Officer (corporate title) |
| CIO | Chief Investment Officer (corporate title) |
| CIO | Congress of Industrial Organizations |
| CIO | Congress of Industrial Organizations (the prior half of the AFL-CIO, 1936-1955) |
| CIO | Check It Out |
| CIO | Comité International Olympique (International Olympic Committee) |
| CIO | Chief Innovation Officer |
| CIO | Centre d'Information et d'Orientation (French) |
| CIO | Career Is Over |
| CIO | Cut It Out |
| CIO | Central Imagery Office |
| CIO | Chairman-In-Office |
| CIO | Chief Intelligence Officer |
| CIO | Chief Immigration Officer |
| CIO | Crying It Out (child care; parenting) |
| CIO | Corporate Information Officer |
| CIO | Corporate Information Office |
| CIO | Confederation of Indian Organisations (est. 1975) |
| CIO | Conventional International Origin |
| CIO | Credit Industriel de l Ouest (French: Western French Bank) |
| CIO | Cisco Information Online |
| CIO | Council of Islamic Organizations |
| CIO | Canada Information Office |
| CIO | Chief Integrity Officer (corporate title) |
| CIO | Coordination, Implementation and Operation |
| CIO | Chief Investigation Officer |
| CIO | Carrier Insertion Oscillator (radio receivers) |
| CIO | Commission Internationale d'Optique (French) |
| CIO | Central Intelligence Officer |
| CIO | Continuous Improvement Opportunity |
| CIO | Comité International d'Orientation (French: Intercommunal Orientation Committee) |
| CIO | Central Imperial Order |
| CIO | Center Information Officer |
| CIO | Collège d'Implantologie Orale |
| CIO | Combat Intelligence Officer |
| CIO | Community Involvement and Outreach Office (Los Alamos National Laboratory) |
| CIO | Command Issuing Office |
| CIO | CIS Information On-Line |
| CIO | Contacts Interviews Orders |
| CIO | Central Indian Ocean |