| New Shift Ltd | Education | 2025 |
| New Villager Ltd | Hospitality | 2019 |
| Next Generation Football Academy Ltd | Education | 2023 |
| Next Generation Sports Coaching Ltd | Education | 2022 |
| Next Thursday Ltd | Professional & scientific | 2022 |
| Nextday Hub Ltd | Wholesale & retail | 2025 |
| Nextengine Ventures Limited | Information & communication | 2015 |
| Ngenze Ltd | Information & communication | 2020 |
| NGO Business Services Ltd | Information & communication | 2019 |
| NIC Industries Limited | Professional & scientific | 2021 |
| Nice Human Limited | Administrative & support | 2022 |
| Nick Corbo Consulting Ltd | Professional & scientific | 2020 |
| Nicki's Accountancy Services Limited | Professional & scientific | 2006 |
| Nics Beauty Limited | Other services | 2015 |
| NIK & Trick Photo Services Limited | Professional & scientific | 2012 |
| Nila Express Ltd | Wholesale & retail | 2024 |
| Nimalanaja Ltd | Wholesale & retail | 2018 |
| Nincomsoup Limited | Hospitality | 1999 |
| Nitoka Ltd | Information & communication | 2026 |
| NM Project & Programme Management Ltd | Professional & scientific | 2026 |
| Noble Industria Ltd | Other services | 2020 |
| Noble Purpose Ltd | Professional & scientific | 2015 |
| Noise and Order Limited | Information & communication | 2023 |
| Nomad Global Ventures Ltd | Wholesale & retail | 2025 |
| Nooa Ltd | Other services | 2024 |
| Noogleberry Limited | Wholesale & retail | 2011 |
| North and South Painting Contractors Ltd | Construction | 2024 |
| North Goliath Ltd | Information & communication | 2017 |
| North Home Care Ltd | Health & social care | 2017 |
| Northfield Nursery (Hythe) Limited | Education | 1995 |
| Northsouth Housing Limited | Real estate | 2015 |
| NOT for Humans Ltd | Wholesale & retail | 2020 |
| Notchco Ltd | Manufacturing | 2020 |
| Noted in Style Limited | Manufacturing | 2012 |
| Nova Security Systems S.E. Ltd | Administrative & support | 2019 |
| November Group Ltd | Hospitality | 2025 |
| Novogara Limited | Other services | 2015 |
| Noyce Interiors Ltd | Manufacturing | 2026 |
| NRP Harmony Holdings Ltd | Financial services | 2026 |
| NS Care and Support Ltd | Administrative & support | 2026 |
| NSR Services Ltd | Professional & scientific | 2019 |
| Nu-Scape Ltd | Administrative & support | 2020 |
| Numerax Consultancy Limited | Construction | 2026 |
| Nutresco Ltd | Wholesale & retail | 2013 |
| Nuway Cleaning Services Limited | Administrative & support | 2021 |
| NW Smith Associates Limited | Construction | 2015 |
| NWL Mechanical Services Ltd | Construction | 2022 |
| NWP Media Limited | Information & communication | 2025 |
| Nyikat Limited | Health & social care | 2013 |
| NZ Plumbing & Heating Ltd | Construction | 2021 |
| O'Sullivan Rail Group Ltd | Wholesale & retail | 2025 |
| Oak Estate Developments LLP | | 2007 |
| Oakleigh Manor Garden Joinery Limited | Manufacturing | 2012 |
| Oakmove Limited | Real estate | 1984 |
| Oaktree Garage (Kingsnorth) Limited | Wholesale & retail | 2011 |
| Oakvale Properties Limited | Professional & scientific | 1990 |
| Obduro AI Limited | Information & communication | 2025 |
| Objectables Publishing Limited | Information & communication | 2021 |
| Obralia ECS Limited | Professional & scientific | 2016 |
| Ocia Properties Ltd | Real estate | 2020 |
| Octachoron Bidco Limited | Financial services | 2022 |
| Octachoron Midco Limited | Financial services | 2022 |
| Octachoron Topco Limited | Financial services | 2022 |
| October Group Sandgate Ltd | Hospitality | 2025 |
| ODD Socks Folkestone CIC | Other services | 2025 |
| Oddballsgolf Ltd | Wholesale & retail | 2024 |
| Oddyo Productions Limited | Professional & scientific | 2024 |
| Oetzmann & Co. Limited | Construction | 2017 |
| OH My Goodies Kent Limited | Hospitality | 2025 |
| OIV International Limited | Information & communication | 2017 |
| OK Business Group Ltd | Other services | 2010 |
| Okay Coffee Ltd | Hospitality | 2024 |
| Oklele Ltd | Wholesale & retail | 2025 |
| Old Endeavour Entertainments Ltd | Wholesale & retail | 2012 |
| Olive Tree Trading Ltd | Professional & scientific | 2023 |
| Oliver Enwonwu Studio Limited | Arts & recreation | 2024 |
| Oliver Okolo Studio Ltd | Arts & recreation | 2025 |
| OLLIE101 Limited | Health & social care | 2022 |
| Ombuku Ltd | Wholesale & retail | 2021 |
| Omkar Limited | Hospitality | 2014 |
| Omni Systems Publishing Ltd | Information & communication | 2023 |
| Omni Warehouse Ltd | Wholesale & retail | 2023 |
| ON Demand Accountants Ltd | Professional & scientific | 2023 |
| ON Solid Ground CIC | Education | 2020 |
| One to Trade Limited | Professional & scientific | 2003 |
| Onslow’S Limited | Professional & scientific | 2026 |
| Ontime Freight Ltd | Transport & logistics | 2018 |
| Ontime Windows Limited | Professional & scientific | 2005 |
| Open Empathic Ltd | Information & communication | 2023 |
| Operation Sunshine | Professional & scientific | 2008 |
| Oportunitas Limited | Real estate | 2014 |
| Opti Consultants Ltd | Wholesale & retail | 2024 |
| Optimal Care Clinic Ltd | Health & social care | 2022 |
| Optimal Power Techniques Limited | Manufacturing | 2012 |
| Optimise HR Limited | Administrative & support | 2012 |
| Optimum Solutions Holdings Limited | Financial services | 2023 |
| Opulent Exhibits UK Ltd | Administrative & support | 2025 |
| Orchard Contracts Limited | Construction | 2013 |
| Orchard Lane Coffee House Ltd. | Hospitality | 2017 |
| Orchard Leisure and Hire Ltd | Construction | 2024 |