| OASAM |
- Office of the Assistant Secretary for Administration and Management |
| OASVET |
- Office of the Assistant Secretary (of Labor) for Veterans' Employment and Training |
| OCD |
- Office of Cost Determination |
| OCFO |
- Office of the Chief Financial Officer |
| OCIA |
- Office of Congressional and Intergovernmental Relations |
| OCIO |
- Office of the Chief Information Officer |
| OECD |
- Organization for Economic Cooperation and Development |
| OES |
- Occupational Employment Statistics |
| OFCCP |
- Office of Federal Contract Compliance Programs |
| OIG |
- Office of the Inspector General |
| OJT |
- On the Job Training |
| OLMS |
- Office of Labor Management Standards |
| OMB |
- Office of Management and Budget |
| OPA |
- Office of Public Affairs |
| OPM |
- Office of Personnel Management |
| OPR |
- Office of Policy and Research OSBP Office of Small Business Programs |
| OSEC |
- Office of the Secretary |
| OSHA |
- Occupational Safety and Health Administration |
| OWCP |
- Office of Workers' Compensation Programs |
