| NQ Medical Limited | Health & social care | 2013 |
| Nrac Consulting Limited | Information & communication | 2022 |
| NRC Automation Ltd | Professional & scientific | 2023 |
| NRS Bookkeeping Services Ltd | Professional & scientific | 2012 |
| Nrswa Engineers Limited | Construction | 2005 |
| NS Change & Project Management Services Limited | Professional & scientific | 2014 |
| NS Power Electronics Limited | Professional & scientific | 2019 |
| Nsew Experience Limited | Health & social care | 2023 |
| NSK Global Ltd | Wholesale & retail | 2014 |
| NSK Investments Ltd | Construction | 2025 |
| Nskr Properties Limited | Real estate | 2020 |
| Ntqs Limited | Education | 2023 |
| NTR Site Engineering Ltd | Construction | 2021 |
| NU Estates Ltd | Real estate | 2018 |
| Nu*Stock Ltd | Extraterritorial | 2002 |
| Nudge (Midlands) Limited | Information & communication | 2026 |
| NUE Media Limited | Professional & scientific | 2006 |
| Nuha Homeida Ltd | Professional & scientific | 2024 |
| Numach Ltd | Wholesale & retail | 2006 |
| Nuovo Kitchen & Home Limited | Wholesale & retail | 2023 |
| Nuovokb Limited | Construction | 2024 |
| Nurture and Flourish Ltd | Health & social care | 2025 |
| Nurv Software Ltd | Information & communication | 2007 |
| Nutan Consulting Limited | Health & social care | 2025 |
| Nutri-Psych Ltd | Wholesale & retail | 2024 |
| Nutricola (Europe) Ltd | Wholesale & retail | 2012 |
| Nutritec Limited | Wholesale & retail | 1987 |
| Nutrition Provocateur Ltd | Wholesale & retail | 2026 |
| Nutrition's Finest Ltd | Wholesale & retail | 2019 |
| Nutrition-Centred Healing Ltd | Health & social care | 2022 |
| Nutritional Foods Limited | Professional & scientific | 2006 |
| Nutriwell UK Ltd | Wholesale & retail | 2020 |
| Nutter Consulting Limited | Professional & scientific | 2023 |
| Nuuku Properties Ltd | Real estate | 2024 |
| NV Properties (West Midlands) Limited | Real estate | 2020 |
| NWD Global Limited | Extraterritorial | 2021 |
| Nwqs Ltd | Education | 2008 |
| NXD007 Limited | Professional & scientific | 2022 |
| NXN Holdings Limited | Financial services | 2020 |
| NXN Ventures Limited | Professional & scientific | 2022 |
| Nxzen Cognitive Earth Limited | Information & communication | 2025 |
| Nxzen Global Limited | Professional & scientific | 2006 |
| Nxzen Limited | Professional & scientific | 2015 |
| Nyanzatech Limited | Wholesale & retail | 2021 |
| NYN Collective Ltd | Administrative & support | 2026 |
| Nyxoratech Ltd | Information & communication | 2025 |
| O & S Propco Limited | Real estate | 2026 |
| O a Onalaja Medical Ltd | Health & social care | 2022 |
| O C Bar Ltd | Hospitality | 2022 |
| O Grove Holdings Limited | Real estate | 2016 |
| O I E a Limited | Professional & scientific | 2024 |
| O T Bathrooms Ltd | Construction | 2014 |
| O&N Property Ltd | Real estate | 2019 |
| O&R Holdings Limited | Financial services | 2025 |
| O&R Technology Ltd | Information & communication | 2025 |
| O'Brien Services Ltd | Health & social care | 2023 |
| O'Brien's Period Restorations Limited | Construction | 2008 |
| O'Neill Partners Ltd | Financial services | 2020 |
| O.R. Building Services Limited | Construction | 1992 |
| OA Property Holdings Ltd | Real estate | 2018 |
| OAC 15 Limited | Real estate | 2023 |
| Oak and Hound Dog Groomers Ltd | Other services | 2025 |
| Oak Avenue Solutions Limited | Information & communication | 2024 |
| Oak Edge Construction Ltd | Construction | 2024 |
| Oak Grove Consulting Limited | Information & communication | 2012 |
| Oak Tax Services Limited | Professional & scientific | 2015 |
| Oaklands (Darlaston) Management Company Limited | Households | 2019 |
| Oakley Meadows (Droitwich) Management Company Limited | Households | 2023 |
| Oakmoore Cars Ltd | Wholesale & retail | 2018 |
| Oakmoore Property Services Ltd | Construction | 2019 |
| Oakpine Associates Limited | Professional & scientific | 1988 |
| Oakridge Developments (Midlands) Limited | Construction | 2012 |
| Oaks-Thompson Limited | Real estate | 1979 |
| Oaktree Fencing Ltd | Construction | 2022 |
| Oakway Estates Ltd | Real estate | 2019 |
| Oakwood Carpentry and Build Ltd | Construction | 2024 |
| Oakwood Carpentry and Building Ltd | Construction | 2021 |
| Oakwood Estate & Mortgages Limited | Real estate | 2021 |
| OAO Property (Midlands) Limited | Real estate | 2025 |
| Oasis Mental Health Support Ltd | Health & social care | 2017 |
| Oasis Southside Limited | Construction | 2018 |
| OAT World Holdings Limited | Financial services | 2023 |
| Oatking Design Ltd | Professional & scientific | 2019 |
| Oatking Ltd | Real estate | 2018 |
| Oatking Solutions Limited | Professional & scientific | 2024 |
| OB1 Investments Limited | Financial services | 2019 |
| Obaidy Propdev Ltd | Real estate | 2018 |
| Oblique Design Limited | Professional & scientific | 2004 |
| Obsidian Consulting Ltd | Professional & scientific | 2022 |
| Occumed Exam Prep Ltd | Education | 2025 |
| OCE Service Limited | Administrative & support | 2025 |
| Ocean Drive Classics Limited | Wholesale & retail | 2018 |
| Oceanstay Residency Ltd | Real estate | 2025 |
| Octane Sports Limited | Arts & recreation | 2024 |
| Octavia House Management Limited | Households | 2001 |
| Octavo Design Limited | Professional & scientific | 2004 |
| Octono Limited | Information & communication | 2012 |
| Octopus C Ltd | Construction | 2022 |
| Oculi Ltd | Real estate | 2021 |
| OFF the PUP Limited | Wholesale & retail | 2021 |