| Ōmokoroa Football Club | Registered | Incorporated Society | - | councillor interest |
| Ōmokoroa Football Club, Ōmokoroa Sports and Recreation Society | Unknown | - | - | councillor interest |
| Ōmokoroa Sports and Recreation Society | Registered | Incorporated Society | - | councillor interest |
| OMX TP Tenders | Unknown | - | - | government contract suppliers |
| On Being Bold - Dreaming Big | Unknown | - | - | corporate donations |
| On Demand Training | Unknown | - | - | government contract suppliers |
| On File | Unknown | - | - | government contract suppliers |
| ON TARGET HUNTING LIMITED | Registered | NZ Limited Company | 7431777 | government contract suppliers |
| ON-BRAND PARTNERS (NZ) LIMITED | Registered | NZ Limited Company | 1904711 | government contract suppliers |
| ONCOSIL MEDICAL NZ LIMITED | Registered | NZ Limited Company | 5892718 | councillor interest |
| ONE DOUBLE FIVE WHARE AWHINA COMMUNITY HOUSE TRUST | Registered | Charitable Trust | - | government contract suppliers |
| ONE ELECTRICAL NZ LIMITED | Registered | NZ Limited Company | 3166925 | government contract suppliers |
| ONE NEW ZEALAND GROUP LIMITED | Registered | NZ Limited Company | 927212 | government contract suppliers |
| ONE NZ HOLDINGS LIMITED | Registered | NZ Limited Company | 7456456 | government contract suppliers |
| ONE STOP RAM SHOP LIMITED | Registered | NZ Limited Company | 3231648 | kanoa recipients |
| One Taupō Trust | Registered | Charitable Trust | - | councillor interest |
| ONELAB LIMITED | Registered | NZ Limited Company | 6534012 | government contract suppliers |
| ONELINK IMPORTS LIMITED | Registered | NZ Limited Company | 6795113 | government contract suppliers |
| Onemana Surf Life Saving Club | Registered | Incorporated Society | - | kanoa recipients |
| Onepointfive Limited + Tonkin & Taylor Limited | Unknown | - | - | government contract suppliers |
| Onerahi Community Association | Registered | Incorporated Society | - | councillor interest |
| ONESHOT EARTHWORKS LIMITED | Registered | NZ Limited Company | 8554466 | government contract suppliers |
| ONETEN Bid & Tender Solutions | Unknown | - | - | government contract suppliers |
| ONFORM PM LIMITED | Registered | NZ Limited Company | 8741955 | government contract suppliers |
| ONG & PARTNERS LIMITED | Registered | - | - | |
| Ongas | Unknown | - | - | government contract suppliers |
| Ongrade Drainage & Excavation Ltd | Unknown | - | - | government contract suppliers |
| ONLINE COMMUNICATIONS LIMITED | Registered | NZ Limited Company | 604870 | government contract suppliers |
| ONLINE REO AGENCY LIMITED | Registered | NZ Limited Company | 8220472 | government contract suppliers |
| ONPOINT NZ (2021) LIMITED | Removed | NZ Limited Company | 8256445 | government contract suppliers |
| ONSITE DEVELOPMENTS LIMITED | Registered | NZ Limited Company | 865365 | government contract suppliers |
| ONSLOW 62 LIMITED | Registered | NZ Limited Company | 6020669 | councillor interest |
| ONTRACK CONTRACTING LIMITED | Registered | NZ Limited Company | 6082290 | government contract suppliers |
| Ōnuku Maori Lands Trust | Registered | Trust | - | kanoa recipients |
| Onus Construction Management Limited | Unknown | - | - | government contract suppliers |
| ONYX HORTICULTURE LIMITED | Registered | NZ Limited Company | 76376 | kanoa recipients |
| Opal Kiwi Packaging Ltd | Unknown | - | - | government contract suppliers |
| OPAWAHO HEATHCOTE RIVER NETWORK INCORPORATED | Registered | - | - | |
| OPEN COMMUNICATIONS LIMITED | Registered | - | - | |
| OPEN COUNTRY DAIRY LIMITED | Registered | NZ Limited Company | 1911063 | councillor interest |
| Open Hand Trust | Unknown | - | - | councillor interest |
| OpenCities (SeamlessCMS) | Unknown | - | - | government contract suppliers |
| Opepe Farm Trust | Registered | Trust | - | councillor interest |
| OPERA IN THE PARK LIMITED | Removed | - | - | |
| Operation Thrive | Unknown | - | - | corporate donations |
| Opex Funding for NGOs | Unknown | - | - | government contract suppliers |
| Ophir Community Welfare Association | Unknown | - | - | councillor interest |
| OPHTHALMIC INSTRUMENT COMPANY LIMITED | Registered | NZ Limited Company | 344658 | government contract suppliers |
| Ōpōtiki College Board of Trustees | Unknown | - | - | kanoa recipients |
| OPOTIKI COUNTY RETURNED AND SERVICES' ASSOCIATION INCORPORATED | Registered | Incorporated Society | - | government contract suppliers |