| Acronym | Meaning |
| PSO | Pakistan State Oil |
| PSO | Patient Safety Organization (Rockville, MD) |
| PSO | Payload Sensor Operator |
| PSO | Peace and Stability Operations (US Army) |
| PSO | Peace Support Operation |
| PSO | Port Security Officer |
| PSO | Possible Survivable Options |
| PSO | Post Security Officer (US DoD) |
| PSO | Power System Operator (various locations) |
| PSO | Preliminary Screening Officer |
| PSO | Pressure Shut Off |
| PSO | Primary Standardization Office |
| PSO | Primary Strike Objective |
| PSO | Principal Scientific Officer |
| PSO | Procurement Support Office |
| PSO | Program Secretarial Officer |
| PSO | Program Staff Office/Officer |
| PSO | Prohibited Steps Order (UK court order) |
| PSO | Project Safety Officer |
| PSO | Project Step Off |
| PSO | Protected Species Observer |
| PSO | Provisions Supply Office |
| PSO | Public Safety Officer |
| PSO | Public Service Obligation (chiefly European) |
| PSO | Publicity Security Officer (US Navy) |