| Oborny, Shirley | Executive Assistant To The City Manager | City Manager | 949-644-3001 | |
| Obrien, James | Firefighter Paramedic 112 Hour 17.25% | Fire | 949-644-3355 | |
| O'Keefe, David | Lifeguard I | Fire | | |
| Othmer, Cole | Lifeguard II | Fire | | |
| Otoole, Michael | Lifeguard I | Fire | | |
| Oseguera, Armando | Fire Engineer 112 Hour | Fire | 949-644-3104 | |
| O'Leary, Ryan | Firefighter Paramedic 112 Hour 22.25% | Fire | 949-644-3104 | |
| Olivas, Jude | Firefighter 112 Hours | Fire | 949-644-3104 | |
| O'Rourke, Brian | Lifeguard Battalion Chief | Fire | 949-644-3045 | |
| Ortiz, Jill | Human Resources Specialist II | Human Resources | 949-644-3310 | |
| Ordiano, Omar | Library Assistant | Library - City | 949-644-3163 | |
| Oconnor, Pamela | Library Clerk I | Library - City | 949-717-3851 | |
| Ornelas, Alejandro | Maintenance Worker I | Public Works Municipal Operations | 949-718-3462 | |
| Oeding, August | Pool Swim Instructor | Recreation | | |
| Odom, Denise | Recreation Leader, Senior | Recreation | | |
| Olazo, Blanca | Senior Services Van Driver | Recreation | 949-644-3244 | |
| O'Campo, Kevin | Utilities Crew Chief | Utilities | 949-718-3437 | |
| O'Sullivan, Mitchell | Utilities Specialist, Senior | Utilities | 949-718-4418 | |
