HKO
| Acronym | Definition |
|---|---|
| HKO | Hong Kong Observatory |
| HKO | Hello Kitty Online (online game; Sanrio, Inc.) |
| HKO | Hong Kong Office |
| HKO | Hrvatski Kvalifikacijski Okvir (Croatian: Croation Qualifying Framework; educational initiative) |
| HKO | Heckler and Koch Oberndorf |
| HKO | Heat Killed Organism |