| New Finsaga Limited | Professional & scientific | 2008 |
| New World (NEC) Limited | Hospitality | 2006 |
| New World Barnsley Limited | Hospitality | 2005 |
| New World Crewe Limited | Hospitality | 2005 |
| New World Haydock Limited | Hospitality | 2004 |
| Newbury House Development Limited | Real estate | 2020 |
| Newfield Homes Limited | Construction | 2025 |
| Newgate RP LP | | 2018 |
| Newglow Engineering Ltd | Professional & scientific | 2011 |
| Newlands Lifestyle Living Ltd | Construction | 2023 |
| Newlands Vehicle Services Limited | Administrative & support | 2026 |
| Next Car NOW Limited | Wholesale & retail | 2015 |
| Next Pathway Ltd | Information & communication | 2024 |
| Nexus Pictures Ltd | Information & communication | 2009 |
| Nexus Security Solutions Limited | Administrative & support | 2021 |
| Nfts Enterprises Ltd | Education | 1979 |
| Nfts Foundation | Education | 1996 |
| NGS Global UK Limited | Other services | 2019 |
| Nicholas King Construction Ltd | Construction | 2004 |
| Nicholas King Homes Group Ltd | Construction | 2023 |
| Nicholas King New Homes Ltd | Construction | 2023 |
| Nicholas King Racing Limited | Administrative & support | 2011 |
| Nicholas King Strategic Ltd | Real estate | 2025 |
| Nickel Group International Ltd | Administrative & support | 2022 |
| Nicky Woolf Ltd | Arts & recreation | 2024 |
| Nightingales Wealth Management Limited | Financial services | 2017 |
| Nile & York Limited | Manufacturing | 2005 |
| Nishas Bakery Ltd | Hospitality | 2026 |
| NK Developments (Cranleigh) Ltd | Construction | 2024 |
| NK Financial Management Limited | Financial services | 2011 |
| NK Trading Group Limited | Information & communication | 2024 |
| Nkce Ltd | Construction | 2011 |
| NKD PLC | Construction | 2008 |
| NKD4 Ltd | Construction | 2010 |
| NKD5 Ltd | Construction | 2011 |
| Nkdb Ltd | Construction | 2020 |
| Nkdsh Ltd | Construction | 2010 |
| NKH 2026 PLC | Construction | 1991 |
| NKH Mera Finance Ltd | Construction | 2025 |
| NKO Digital Limited | Wholesale & retail | 2014 |
| NKP 2026 Ltd | Construction | 2009 |
| NM Productions Limited | Information & communication | 2006 |
| Nolabs AI Ltd | Information & communication | 2025 |
| Nomad Editing Company, Ltd | Information & communication | 2008 |
| Nomadic Land Limited | Real estate | 2024 |
| Nomadic Properties Limited | Real estate | 2023 |
| Nomadified Limited | Information & communication | 2002 |
| Nomir Ahmed Ltd | Health & social care | 2024 |
| Nook Studios Ltd | Arts & recreation | 2026 |
| Nordlys Holdings Limited | Financial services | 2022 |
| North Point Family Investment Company Limited | Financial services | 2023 |
| Norz Ltd | Health & social care | 2020 |
| Nota Construction Ltd | Construction | 2022 |
| Nova Oaks Ltd | Construction | 2026 |
| Novice Limited | Professional & scientific | 2005 |
| Novus Projects London Ltd | Real estate | 2021 |
| Npaidy Ltd | Health & social care | 2017 |
| NR5 Ranworth Ltd | Real estate | 2023 |
| NSP Developments Ltd | Construction | 2013 |
| NSS Accounting Ltd | Professional & scientific | 2017 |
| Nuach Ltd | Manufacturing | 2020 |
| Nutemps Ltd | Administrative & support | 2024 |
| Nvisio Ltd | Professional & scientific | 2024 |
| Nygma IP Ltd | Information & communication | 2021 |
| O&H Developments Ltd | Construction | 2023 |
| Oak END Limited | Real estate | 2012 |
| Oaklands Park (Esher) Management Company Limited | Households | 2023 |
| Oakleaf Building Surveyors Ltd | Professional & scientific | 2014 |
| Oakley Estate Freehold Company Limited | Professional & scientific | 2003 |
| Oakmede Developments Limited | Construction | 1962 |
| Oakthorn Ltd | Professional & scientific | 2025 |
| Oakwood Resourcing Limited | Administrative & support | 2015 |
| Oberon Art Limited | Wholesale & retail | 2002 |
| OBS Data Consult Ltd | Information & communication | 2023 |
| Ochtwood Management Consulting UK Limited | Professional & scientific | 2010 |
| Odyssey Labs Limited | Information & communication | 2024 |
| Odyssey Refurbishment Company Limited | Construction | 1999 |
| Offer Page Limited | Information & communication | 2023 |
| OIL and Grains Limited | Manufacturing | 2026 |
| Old House Westcott Developments Limited | Construction | 2018 |
| Old Malthouse Lane Management Company Limited | Administrative & support | 2014 |
| Old Trafford Limited | Professional & scientific | 2015 |
| Oldbean Ltd | Wholesale & retail | 2024 |
| Oldefield Equestrian Centre Limited | Agriculture & fishing | 2003 |
| Oligo Limited | Mining & quarrying | 2012 |
| Olive Consulting Limited | Information & communication | 2004 |
| Omni Booths Limited | Wholesale & retail | 2026 |
| Omnio Services Ltd | Professional & scientific | 2025 |
| Omniquest Ventures Ltd | Real estate | 2025 |
| Omnispace UK Limited | Information & communication | 2012 |
| One Sports Network Limited | Arts & recreation | 2025 |
| One to One Estate Management Ltd | Real estate | 2016 |
| ONE3NINE Ventures Limited | Administrative & support | 2010 |
| Onomax Limited | Professional & scientific | 2020 |
| Oppronex Ltd | Professional & scientific | 2026 |
| OPS Surveyors Ltd | Construction | 2018 |
| Optima Connections Limited | Administrative & support | 1989 |
| Optimum Management and Media Limited | Professional & scientific | 2021 |
| Opus Landscapes Ltd | Administrative & support | 2023 |
| Orbitpress Limited | Manufacturing | 1982 |