| Myfilm Ltd | Information & communication | 2022 |
| Mypad Paisley Limited | Hospitality | 2014 |
| MYS Enterprise Ltd | Transport & logistics | 2024 |
| MYW Choreography and Gymnastic Services Limited | Arts & recreation | 2012 |
| MYX Corp Ltd | Real estate | 2024 |
| N G S Food and Wine Limited | Wholesale & retail | 2015 |
| N-Joy Communications Limited | Wholesale & retail | 2000 |
| N.A.R. (UK) Limited | Administrative & support | 1980 |
| Naanandsizzle Ltd | Hospitality | 2020 |
| Natalie Driver Limited | Professional & scientific | 2016 |
| Nataliya Couture Limited | Extraterritorial | 2014 |
| Nataliya Limited | Wholesale & retail | 2010 |
| National Medicare Services Group Limited | Health & social care | 2024 |
| National Medicare Services Ltd | Health & social care | 2022 |
| Natural Angel Beauty Limited | Other services | 2023 |
| Nature Literacy CIC | Professional & scientific | 2026 |
| Nature's Finest Food Products Limited | Wholesale & retail | 2011 |
| Navigo Law Ltd | Professional & scientific | 2017 |
| Navigo Legal Services Limited | Professional & scientific | 2017 |
| Navigo Robotics Limited | Information & communication | 2019 |
| Navy Summerwood Ltd | Professional & scientific | 2016 |
| Nazcot Financial Ltd | Financial services | 2015 |
| Nehra Holdings Limited | Real estate | 2019 |
| Neocity Limited | Information & communication | 2004 |
| Nestport Limited | Professional & scientific | 2005 |
| Neurolingua Limited | Professional & scientific | 2008 |
| New Beginnings (Wisbech) Ltd | Health & social care | 2008 |
| New Company Services Limited | Information & communication | 1999 |
| New Doors Ascot Limited | Wholesale & retail | 2018 |
| New Place Freehold Ltd | Households | 2022 |
| Newco Brands Ltd | Wholesale & retail | 2026 |
| Newson Investments Ltd. | Real estate | 2016 |
| Nexium Vital Gate Limited | Health & social care | 2021 |
| Ngolarn Ltd | Health & social care | 2022 |
| Nice 1 OWS Limited | Wholesale & retail | 2021 |
| Nicholls Architecture and Design Ltd | Professional & scientific | 2014 |
| Nicola Cooke Ltd | Administrative & support | 2023 |
| Nightjar Consulting Limited | Professional & scientific | 2014 |
| Nimsters Creative Limited | Professional & scientific | 2025 |
| Nina Morris Limited | Wholesale & retail | 2016 |
| Niras Consulting Limited | Extraterritorial | 2010 |
| Niras Fraenkel Ltd | Extraterritorial | 1995 |
| Niras Group (UK) Ltd | Professional & scientific | 1976 |
| Nissy U.K. Limited | | 1982 |
| Niteshyft Limited | Professional & scientific | 2021 |
| NM Development Ltd | Real estate | 2024 |
| NMS Community CIC | Public administration | 2025 |
| NO More Nits Ltd | Professional & scientific | 2019 |
| NO.33 Trinity Ltd | Professional & scientific | 2025 |
| Noctor's Limited | Hospitality | 2007 |
| Nomadic OPS Ltd | Administrative & support | 2025 |
| Noodle Vision Ltd | Information & communication | 2021 |
| Normaxe Finance Limited | Information & communication | 2010 |
| Norris Consultancy Ltd | Professional & scientific | 2026 |
| North Star Strategic Consultancy Ltd | Transport & logistics | 2023 |
| Northpoint Construction Limited | Construction | 2025 |
| Norton Invest Ltd | Real estate | 2025 |
| Norton Wells Holdings Limited | Real estate | 2019 |
| Norton Wells Limited | Wholesale & retail | 2025 |
| Norton Wells UK LLP | | 2013 |
| Notbadvinny Ltd | Professional & scientific | 2015 |
| Nowsecure Ltd | Professional & scientific | 2021 |
| Nrcm Limited | Professional & scientific | 2018 |
| Nucleus PDS Limited | Transport & logistics | 2015 |
| Number Eleven Ltd | Information & communication | 2021 |
| Nuts at Heart Limited | Manufacturing | 2021 |
| O S R Construction & Groundworks Ltd | Construction | 2026 |
| Oakenplus Investments Limited | Professional & scientific | 2013 |
| Oaks Property Services Limited | Construction | 2002 |
| Oasis Landscape Gardening Limited | Administrative & support | 2005 |
| Objectborn+ Ltd | Wholesale & retail | 2022 |
| Obsidian IO Limited | Information & communication | 2020 |
| Occleve Limited | Professional & scientific | 2025 |
| Ocean Polymers Limited | Water & waste | 2017 |
| Ocean Waves Break Ltd | Professional & scientific | 2025 |
| October Farm Ltd | Agriculture & fishing | 2025 |
| Octopus Holdings Limited | Construction | 2005 |
| Octopus Rentals Limited | Administrative & support | 2002 |
| Odeon Interactive Ltd | Information & communication | 2024 |
| OFF Beat Branding Limited | Professional & scientific | 2026 |
| Ogmios Management Consultants Limited | Administrative & support | 2013 |
| Ohten On-Line Training Limited | Professional & scientific | 2021 |
| Okean Capital Ltd | Wholesale & retail | 2021 |
| Old School Place (Ascot) RES. Assoc. Limited | Households | 1994 |
| Oliver Garcia Ltd | Arts & recreation | 2015 |
| Olympia International Limited | Wholesale & retail | 2015 |
| Omnya Ltd | Wholesale & retail | 1998 |
| Omolon Ltd | Information & communication | 2025 |
| One Stop Creative Agency Limited | Information & communication | 2018 |
| One Take Location Services Ltd | Administrative & support | 2025 |
| Ontoit Ltd | Information & communication | 2024 |
| Opalflex Limited | Extraterritorial | 1983 |
| Opti-T Services Ltd | Wholesale & retail | 2025 |
| Optic Aerials & Network Services Ltd | Construction | 2021 |
| Optima Research Group Ltd | Wholesale & retail | 2026 |
| Optimal Inventories Limited | Real estate | 2023 |
| Opus Knee LLP | | 2016 |
| Orchardwood Estates Limited | Administrative & support | 1992 |
| Original Cinema Ltd | Information & communication | 2015 |
| Orlandoattractions Ltd | Administrative & support | 2018 |