| Obidyke's Limited | Health & social care | 2020 |
| Objedo Ltd | Arts & recreation | 2022 |
| OBR Management Limited | Arts & recreation | 2020 |
| Obscura Cafe Limited | Hospitality | 1998 |
| Obsidian Risk Group Limited | Administrative & support | 2025 |
| OC Online Ltd | Wholesale & retail | 2023 |
| OCA Consulting Ltd | Information & communication | 2022 |
| Ocam Solutions Ltd | Information & communication | 2025 |
| Occ-Health Ltd | Professional & scientific | 2011 |
| Ocdav Associates Limited | Wholesale & retail | 2014 |
| Ocean & Sea Ltd | Administrative & support | 2025 |
| Ocean BH14 Ltd | Hospitality | 2023 |
| Ocean Breeze Freehold Limited | Households | 2010 |
| Ocean Breeze Management Ltd | Households | 2004 |
| Ocean Colour Print Limited | Manufacturing | 2009 |
| Ocean Court Services Company Limited | Households | 2007 |
| Ocean Dentalcare Ltd | Health & social care | 2020 |
| Ocean Doctor Ltd | Health & social care | 2025 |
| Ocean Edge Properties Ltd | Real estate | 2023 |
| Ocean Founders Ltd | Education | 2026 |
| Ocean Marine Systems Holdings Limited | Professional & scientific | 2013 |
| Ocean Marine Systems Limited | Manufacturing | 2013 |
| Ocean Point Properties Limited | Households | 2016 |
| Ocean Properties Holdings Limited | Real estate | 2022 |
| Ocean View Freehold Limited | Households | 2001 |
| Ocean Yacht Systems Limited | Administrative & support | 1989 |
| Oceanplastering Ltd | Construction | 2022 |
| Oceans Homes Ltd | Real estate | 2018 |
| Oceanside Developments Limited | Construction | 2023 |
| Oceanside Surveying Limited | Professional & scientific | 2026 |
| Oceanspace Communications Limited | Professional & scientific | 2023 |
| Oceantide Limited | Administrative & support | 2012 |
| Ocengen Ltd | Professional & scientific | 2025 |
| Ochi Idun Wellthiness Ventures Ltd | Other services | 2025 |
| OCS Flats 15-17 Limited | Households | 2000 |
| Octatech Ltd | Information & communication | 2025 |
| Octo Homes Limited | Real estate | 2015 |
| Octopus Auto Services Limited | Wholesale & retail | 2025 |
| Octopus Consortium Limited | Information & communication | 2020 |
| Octopy.It Ltd | Real estate | 2018 |
| OCW Limited | Real estate | 2017 |
| ODA Interiors Ltd | Professional & scientific | 2020 |
| ODW Garden Services Ltd | Administrative & support | 2026 |
| Odyssey (Poole) Management Limited | Households | 2008 |
| Office Boffin Limited | Wholesale & retail | 2020 |
| Official Cosmetics Ltd | Wholesale & retail | 2025 |
| Offshore Energy Solutions Ltd | Transport & logistics | 2013 |
| Offshore Racing Limited | Administrative & support | 1999 |
| Offshore Raffle Limited | Wholesale & retail | 2025 |
| Offskin Ltd | Manufacturing | 2025 |
| OFK Limited | Wholesale & retail | 2024 |
| OG Investment SPV Ltd | Real estate | 2025 |
| Og-Builders Ltd | Construction | 2025 |
| Ogkreatives Media Ltd | Information & communication | 2025 |
| Ogos Properties Limited | Real estate | 2021 |
| Ogpeg Limited | Manufacturing | 2023 |
| OHC (EOT) Ltd | Administrative & support | 2022 |
| Oipas Limited | Arts & recreation | 2026 |
| Oishiipanasian Limited | Hospitality | 2022 |
| OJM Landscapes Ltd | Administrative & support | 2023 |
| OK Accountants Limited | Professional & scientific | 2019 |
| Oklah Services Limited | Transport & logistics | 2025 |
| Okmau Resources Ltd | Wholesale & retail | 2021 |
| Okowarme Limited | Manufacturing | 2026 |
| Okoye Homes Ltd | Real estate | 2026 |
| Oktoberfest Events Ltd | Arts & recreation | 2023 |
| OLA Brazil Ltd | Wholesale & retail | 2023 |
| OLA Capital Investments Limited | Real estate | 2025 |
| Old Brewery (Bournemouth) LLP | | 2017 |
| Old Fashioned Construction Limited | Construction | 2016 |
| Old Money Moustache Limited | Wholesale & retail | 2019 |
| Old Oak Film Ltd | Information & communication | 2020 |
| Olego Ltd | Transport & logistics | 2022 |
| Olibella Wealth Limited | Real estate | 2019 |
| Olicloud Limited | Professional & scientific | 2021 |
| Olimp Property Group Limited | Real estate | 2025 |
| Olive Crown & Co. Limited | Transport & logistics | 2026 |
| Olive I.T. Services Limited | Information & communication | 2006 |
| Olive Poole Hill Cafe Limited | Hospitality | 2014 |
| Olive RD STN Property Ltd | Real estate | 2026 |
| Oliver Green Garden Services Ltd | Administrative & support | 2019 |
| Oliver James Home Improvements Ltd | Construction | 2011 |
| Olivera Ltd | Wholesale & retail | 2020 |
| Olivero OIL Ltd | Administrative & support | 2018 |
| Olives Opulent Design Ltd | Administrative & support | 2025 |
| Olivia AI Network Ltd | Administrative & support | 2019 |
| Olivia Close (Hamworthy) Management Company Limited | Households | 2006 |
| Olivia Evangeline Ltd | Manufacturing | 2021 |
| Ollen Services Ltd | Professional & scientific | 2017 |
| Ollen Wellbeing & Finance CIC | Professional & scientific | 2026 |
| Ollie Apps Ltd | Information & communication | 2019 |
| Olliver Douglas Consulting Ltd | Information & communication | 2026 |
| OLM Property Developments Limited | Construction | 2024 |
| Olvicarm Limited | Health & social care | 2010 |
| Olympus Pure Muscle Ltd | Arts & recreation | 2025 |
| OM Care Connect Health Care Ltd | Administrative & support | 2018 |
| OM Properties Bournemouth Ltd | Real estate | 2021 |
| Ombre Interior Design Ltd | Construction | 2019 |
| OMH Land Ltd | Construction | 2022 |
| Omni Chimaera Limited | Health & social care | 2025 |