| 511 | Ocsc Global Pte. Ltd. 199104788D | Active |
| 512 | Ong Michael Dr
| Active |
| 513 | Orange Media Group Pte. Ltd. 200801434D | Active |
| 514 | Ong K H Clare
| Active |
| 515 | Oceano Electrical Trading Pte Ltd 200005830N | Active |
| 516 | Ocean Granites (S) Pte Ltd
| Active |
| 517 | Ocs Data & Records Management Services (S) Pte Ltd
| Active |
| 518 | Optics Premier Pte Ltd 199305756G | Active |
| 519 | Oas (s) Pte Ltd 198900766N | Active |
| 520 | Octogram Press Pte Ltd 199104881C | Active |
| 521 | Ong Leong Boon Dr
| Active |
| 522 | Optima Daribell Pte Ltd 199804318C | Active |
| 523 | Optibelt Asia Pacific Pte Ltd 199700295G | Active |
| 524 | Ong Radio Int'l Pte Ltd
| Active |
| 525 | Optics & Photonics Society Of S'pore
| Active |
| 526 | Optiqua Technologies Pte. Ltd. 200715458M | Active |
| 527 | Orica S'pore Pte Ltd
| Active |
| 528 | Optimal Medical Products Pte Ltd 200005742N | Active |
| 529 | Orange Valley Nursing Homes Pte. Ltd. 199204659E | Active |
| 530 | Omni Mold Ltd. 198905059N | Active |
| 531 | Olympus S'pore Pte Ltd
| Active |
| 532 | Overseas Technical Engineering & Construction Pte Ltd
| Active |
| 533 | Omark Worldwide (s) Pte Ltd 199802781Z | Active |
| 534 | Oxley Hill Properties Pte Ltd 199508391C | Active |
| 535 | Oel (holdings) Limited 198403368H | Active |
| 536 | Overseas Motors (private) Limited 195600088M | Active |
| 537 | Ohin Construction Co. Pte. Ltd. 197300799W | Active |
| 538 | Oceanic Offshore Engineering Pte. Ltd. 200307793M | Active |
| 539 | Orion Offshore Engineering & Construction Pte Ltd
| Active |
| 540 | Orchard Maritime Services Pte Ltd
| Active |