| MSO IT Ltd | Information & communication | 2025 |
| MTM Solutions Kent Ltd | Wholesale & retail | 2024 |
| Muchamore Limited | Arts & recreation | 2012 |
| Mudd Limited | Real estate | 2003 |
| Multibase Systems Limited | Information & communication | 2005 |
| Mulvany Data Solutions Ltd | Information & communication | 2024 |
| MVB Innovations Ltd | Professional & scientific | 2022 |
| MVH Engineering Limited | Professional & scientific | 2014 |
| MVM Buiilding Ltd | Construction | 2013 |
| MW Payroll Solutions Ltd | Professional & scientific | 2022 |
| MW Services (Kent) Limited | Construction | 2016 |
| Mytholite Ltd | Information & communication | 2023 |
| N & I Healthcare Limited | Health & social care | 2015 |
| N & I Holdings Limited | Financial services | 2015 |
| N & I Investments Ltd | Real estate | 2014 |
| N W Grigg Limited | Transport & logistics | 2018 |
| Nadeswara College Old Student Association UK | Other services | 2023 |
| Nail N Nail Beauty Salon Limited | Other services | 2026 |
| Nandana Limited | Wholesale & retail | 2017 |
| Nangs Thai Spa Ltd | Other services | 2026 |
| NAR Care Homes Ltd | Health & social care | 2022 |
| Nasufi Property Limited | Construction | 2023 |
| Native Liberty Productions Ltd | Information & communication | 2018 |
| NCB Services Ltd | Construction | 2018 |
| Nd&Rd Limited | Real estate | 2021 |
| NE Consultants Ltd | Education | 2023 |
| Necessary Furniture | Health & social care | 1999 |
| NED Prime Ltd | Transport & logistics | 2026 |
| Negasonic Ventures Ltd | Other services | 2024 |
| Neil Harrison Consulting Ltd | Professional & scientific | 2024 |
| Neroitalia Ltd | Wholesale & retail | 2020 |
| Neville Way Management Limited | Households | 2007 |
| New & Used Tyres Limited | Wholesale & retail | 2023 |
| New Flying Horse Ltd | Hospitality | 2018 |
| New Hope Stray Services Ltd | Other services | 2020 |
| New Resin Contractors Ltd | Administrative & support | 2016 |
| Newbery Electricals Limited | Construction | 2004 |
| Newkraft Builders Ltd | Construction | 2013 |
| Nige Partnership Ltd | Real estate | 2012 |
| Nigel Bunning Ltd | Information & communication | 2017 |
| Nine Seventeen Clothing Ltd | Wholesale & retail | 2026 |
| NL Roofing & Building Services Ltd | Construction | 2025 |
| NO Stress Process Ltd | Administrative & support | 2024 |
| Noah NUH Limited | Hospitality | 2025 |
| Northeast Naturals Ltd | Administrative & support | 2014 |
| Northern Lights Partnership Limited | Health & social care | 2014 |
| Norton Design Associates Limited | Professional & scientific | 2020 |
| NOT Just a Room Kent Ltd | Real estate | 2019 |
| NOT Just YOU CIC | Education | 2025 |
| Nport Limited | Wholesale & retail | 2023 |
| NR Cartontech Solutions Ltd | Wholesale & retail | 2026 |
| NS Land & Properties Limited | Real estate | 2014 |
| NU Nashville Pets Ltd | Arts & recreation | 2023 |
| NU Start Health Limited | Health & social care | 2014 |
| Numac Mechanical Heating and Plumbing Services Ltd | Construction | 2020 |
| Nunhead Roofing and Building Services Limited | Construction | 2018 |
| Nunhead Roofing London Limited | Construction | 2019 |
| Nurian Ltd | Arts & recreation | 2023 |
| Nutracrest Ltd | Professional & scientific | 2018 |
| NW Consulting (SE) Limited | Professional & scientific | 2025 |
| Oak Ridge Frames Limited | Construction | 2018 |
| Oasis Central Ltd | Real estate | 2018 |
| Oast Architecture Limited | Professional & scientific | 2015 |
| Oastview Builders & Electrical Ltd | Construction | 2017 |
| Ocean Abseiling Ltd | Administrative & support | 2015 |
| Office & Educational Furniture Limited | Wholesale & retail | 2016 |
| Ogundipe Healthcare Limited | Health & social care | 2024 |
| Ogutlu Ltd | Hospitality | 2018 |
| OKY Toky Limited | Information & communication | 2023 |
| Oliver Holdings Kent Ltd | Real estate | 2026 |
| OLIVESRGOOD4U Limited | Wholesale & retail | 2001 |
| One X Electrical Limited | Construction | 2021 |
| Onizion Ltd | Manufacturing | 2026 |
| Onyx Water Treatment Limited | Water & waste | 2017 |
| Opeg Extras Dwelling Ltd | Real estate | 2021 |
| Opuntia Holdings Limited | Financial services | 2021 |
| Orchard Employment Law Ltd | Administrative & support | 2015 |
| Orchestra Facilities Management Ltd | Professional & scientific | 2024 |
| Organised Kayos Ltd | Construction | 2025 |
| Orla Homes Limited | Health & social care | 2018 |
| ORT Holdings Ltd | Real estate | 2020 |
| Oryo Group Ltd | Wholesale & retail | 2023 |
| Osinde & SON Ltd | Construction | 2023 |
| Oskar's Barbers Ltd | Other services | 2017 |
| Ospringe Solutions Limited | Professional & scientific | 2007 |
| OTT Groundworks and Landscape Ltd | Construction | 2025 |
| Oturner Group Ltd | Wholesale & retail | 2021 |
| Oturner Holdings Ltd | Financial services | 2025 |
| Oturner Investments Ltd | Financial services | 2025 |
| Outback Property Limited | Real estate | 2022 |
| Outer Space Construction Limited | Administrative & support | 2017 |
| Ovabell Limited | Hospitality | 2014 |
| Owen & Co (Roofing & Building Services) Limited | Construction | 2015 |
| Oxels Ltd | Information & communication | 2026 |
| Oyster Cleaning Services Limited | Administrative & support | 2018 |
| Oyster Financial Solutions LLP | | 2010 |
| Oyster General Insurance Services Limited | Financial services | 2018 |
| Oyster Mortgage Services Limited | Financial services | 2004 |
| Oyster Property Solutions Limited | Real estate | 2011 |
| P & P (UK) Ltd | Hospitality | 2005 |