| NW Home Maintenance Ltd | Administrative & support | 2026 |
| NW MSK Imaging LLP | | 2019 |
| NW Resin Flooring Ltd | Construction | 2026 |
| NW Trading (Birkenhead) Limited | Transport & logistics | 2008 |
| NW Trading (Caldaire) Limited | Transport & logistics | 2004 |
| NW Trading (Holdings) Limited | Financial services | 2006 |
| NW Trading (Humber) Limited | Transport & logistics | 2005 |
| NW Trading (Logistics) Limited | Transport & logistics | 2006 |
| NWC M&E Services Ltd | Construction | 2014 |
| NWIS24 Limited | Administrative & support | 2024 |
| NWT Design & Build Limited | Construction | 2019 |
| NXT Tanners Ltd | Wholesale & retail | 2025 |
| NYL Consulting Limited | Professional & scientific | 2018 |
| O & F Design Limited | Wholesale & retail | 2016 |
| O J W Estates Limited | Real estate | 2024 |
| O OOI Ltd | Health & social care | 2022 |
| O&D Electrical Ltd | Administrative & support | 2012 |
| O'Donohoe Property Ventures Ltd | Construction | 2026 |
| O'Meara Fitzmaurice Limited | Professional & scientific | 2017 |
| OAG Safe Ltd | Professional & scientific | 2024 |
| Oak Court Residents Association Limited | Households | 2010 |
| Oakbank Developments NW Ltd | Manufacturing | 2023 |
| Oakbrook Property Developments Limited | Real estate | 2020 |
| Oakenfull Ventures Ltd | Other services | 2021 |
| Oakfield Management Limited | Wholesale & retail | 2024 |
| Oakhills Property Ltd | Real estate | 2023 |
| Oakley Trading Limited | Wholesale & retail | 2020 |
| Oakmere Contractors Limited | Construction | 1995 |
| Oakmere Finance Limited | Financial services | 2015 |
| Oakmont Commercial Consultany Ltd | Professional & scientific | 2026 |
| Oakridge (Adams) Limited | Administrative & support | 2020 |
| Oakwood Builders Limited | Professional & scientific | 1993 |
| Oakwood Farm Chester Limited | Hospitality | 2016 |
| Oakwood Healthcare Solutions (North) Limited | Health & social care | 2025 |
| Oakwood Healthcare Staffing Solutions Limited | Administrative & support | 2025 |
| Oakwood Pubs Ltd | Hospitality | 2016 |
| OAM Technical Limited | Professional & scientific | 2022 |
| OAS Digital Ltd | Professional & scientific | 2025 |
| OAS Holdings Ltd | Professional & scientific | 2026 |
| Oasis Watering Hole Limited | Wholesale & retail | 2004 |
| OB Construction NW Limited | Construction | 2026 |
| OB Electrical NW Ltd | Construction | 2023 |
| Obec Properties Ltd | Construction | 2025 |
| Obsidian Studios Ltd | Arts & recreation | 2014 |
| OCB Consulting Ltd | Professional & scientific | 2025 |
| OCD Independent Porsche Specialists Limited | Wholesale & retail | 2014 |
| Ocea Dynamic Solutions Ltd | Information & communication | 2024 |
| Ocean Star Thingwall Ltd | Hospitality | 2025 |
| Octus Desserts Ltd | Wholesale & retail | 2026 |
| Ocular Media Ltd | Information & communication | 2020 |
| ODD Balm Limited | Manufacturing | 2024 |
| Odell & Associates Limited | Administrative & support | 2002 |
| Odowd Events Corporate Hospitality Services Limited | Hospitality | 2016 |
| OES Installations Ltd | Construction | 2014 |
| OFF the Ground Productions Ltd. | Arts & recreation | 1997 |
| OFF the TEE Limited | Wholesale & retail | 2021 |
| Offhours Labs Ltd | Information & communication | 2026 |
| Office K Limited | Administrative & support | 2010 |
| Officeline Supplies Ltd | Wholesale & retail | 2025 |
| Official World Ltd | Wholesale & retail | 2026 |
| Offshore Wind Energy Limited | Other services | 2010 |
| Offsite Alliance C.I.C. | Construction | 2020 |
| Ofl-Solutions Limited | Professional & scientific | 2024 |
| OGR Project Services Limited | Manufacturing | 2016 |
| OH C'Est LA VIE Ltd | Manufacturing | 2021 |
| OH Chlo Hair Extensions Ltd | Other services | 2023 |
| Ohanas Events Ltd | Hospitality | 2025 |
| Ohhcrumbs Ltd | Hospitality | 2024 |
| OHR Ltd | Health & social care | 2015 |
| OJT Maintenance Services Ltd | Administrative & support | 2025 |
| Okeeffes Engraving Ltd | Manufacturing | 2019 |
| Oktoanalytics Ltd. | Information & communication | 2018 |
| Olaya & Cole Ltd | Real estate | 2024 |
| Olaya & DL Ltd | Real estate | 2024 |
| Olaya & JM Limited | Real estate | 2025 |
| Olaya & Skulpt Living Ltd | Real estate | 2024 |
| Olaya Construction Limited | Construction | 2022 |
| Olaya Investments Ltd | Real estate | 2023 |
| Olaya Property Investments Limited | Real estate | 2024 |
| Olaya Property Management Ltd | Households | 2023 |
| Olaya Rentals Ltd | Real estate | 2024 |
| Olaya Residential Ltd | Financial services | 2023 |
| Old Georgian Properties Ltd | Households | 2018 |
| Old Hall Car Sales & Van Hire Ltd | Administrative & support | 2019 |
| Old Hall Service Station Ltd | Wholesale & retail | 2022 |
| Old Kiln Angling Limited | Wholesale & retail | 2014 |
| Old Kiln Fisheries Limited | Agriculture & fishing | 2021 |
| Old Woking Property Ltd | Construction | 2023 |
| Oldcastle Consultancy Limited | Administrative & support | 2023 |
| Olde Forge Holdings Limited | Real estate | 2004 |
| Oldfield Associates Ltd | Administrative & support | 2009 |
| Oldfield Chase (Heswall) Management Company Limited | Households | 2023 |
| Oldfield Consulting Limited | Professional & scientific | 2014 |
| Olho Ltd | Financial services | 2022 |
| Olife Labs Limited | Information & communication | 2026 |
| Olimere Construction Ltd | Construction | 2025 |
| Olirey Ltd | Households | 2023 |
| Olive Barrel Ltd | Hospitality | 2025 |
| Olive Grove Stays Limited | Real estate | 2024 |
| Olive Hues Ltd | Real estate | 2025 |