DCO
- Deep Carbon Observatory
- Developer Certificate of Origin
- Device configuration overlay
- Digital Cooperation Organization
- Digitally controlled oscillator
- Dimension Century Orguss
- Direct commission officer
- Disney Channel Original (disambiguation)
- District coordination officer
- Domain controller
- Drift City
- Dynamic Creative Optimization
- Middlesex Regiment
- Siemens DCO
- The British Columbia Regiment (Duke of Connaught's Own)
- United States District Court for the District of Colorado