| Medstead Meats Ltd | Manufacturing | 2018 |
| Melezes Capital Limited | Financial services | 2025 |
| Merlyn Phoenix Limited | Transport & logistics | 2009 |
| Metrics Limited | Professional & scientific | 2004 |
| MGH Sport Horse Stud Ltd | Agriculture & fishing | 2015 |
| Mi-Living Ltd | Information & communication | 2015 |
| Middleton Millard Ltd | Professional & scientific | 2024 |
| Mike Clayton Ltd | Professional & scientific | 2025 |
| Mill Medical Ltd | Real estate | 2020 |
| MKR Homes 01 Limited | Construction | 2024 |
| MKR Homes 02 Limited | Construction | 2025 |
| MKR Homes 03 Limited | Construction | 2025 |
| Mlcc Building & Maintenance Ltd | Construction | 2022 |
| Mmpds Ltd | Households | 2012 |
| Mobile Commerce Ventures Limited | Information & communication | 2009 |
| Moda Rosa Ltd | Wholesale & retail | 2024 |
| Modern Giving Limited | Information & communication | 2023 |
| Monica B.Welburn Limited | Information & communication | 2013 |
| Moomix Limited | Manufacturing | 2009 |
| Moon Roast Limited | Wholesale & retail | 2012 |
| Moonmoon Ltd | Wholesale & retail | 2018 |
| Mora Distribution 2009 Limited | Wholesale & retail | 2025 |
| Mora Distribution Ltd | Wholesale & retail | 2009 |
| Morestead Racing LLP | | 2026 |
| Moribus Ltd | Health & social care | 2016 |
| Mount 1959 Limited | Extraterritorial | 2013 |
| MR K Group Limited | Financial services | 2026 |
| MSA Pubs Limited | Hospitality | 2025 |
| Mulligan Golf Management Ltd | Arts & recreation | 2013 |
| Multiskill Communications Ltd. | Construction | 1994 |
| Mysoulpurpose Ltd | Wholesale & retail | 2026 |
| N J Arts Limited | Real estate | 2019 |
| Natalie Young Ltd | Information & communication | 2013 |
| Natdogs Ltd | Professional & scientific | 2016 |
| Navistrak Limited | Extraterritorial | 2003 |
| NCS Information Ltd | Professional & scientific | 2020 |
| Neall Therapies Ltd | Health & social care | 2015 |
| Nexus Presence Ltd | Professional & scientific | 2025 |
| NIC Joly Limited | Arts & recreation | 2015 |
| Nick Durning Ltd | Professional & scientific | 2024 |
| Ninety-One Winchester Limited | Other services | 2024 |
| Nomad Coffee Ltd | Hospitality | 2025 |
| Nordhavn Europe Limited | Wholesale & retail | 2003 |
| Northbrook Farms Limited | Agriculture & fishing | 1994 |
| Nunatak Systems Limited | Manufacturing | 2022 |
| O & L East Livestock Ltd | Agriculture & fishing | 2023 |
| Oak Tree Landscapes Limited | Administrative & support | 2013 |
| Oaktree Place Right to Manage Company Limited | Households | 2016 |
| Observant Innovations Limited | Manufacturing | 2013 |
| Observant Technology Limited | Manufacturing | 2013 |
| Ocean Commodities Limited | Administrative & support | 1990 |
| Oceans Worldwide Limited | Extraterritorial | 2010 |
| Octavia Hamilton Ltd | Health & social care | 2021 |
| Ocular Solutions Limited | Health & social care | 1999 |
| Odyssey Boats Limited | Manufacturing | 2023 |
| Olivia George Bridal Couture Limited | Wholesale & retail | 2023 |
| Olivia George Bridal Limited | Extraterritorial | 2019 |
| Olivia M Hunt Consulting Ltd | Administrative & support | 2026 |
| ON the BIT Marketing Limited | Professional & scientific | 2023 |
| Onepwd Limited | Real estate | 2025 |
| Organeco Ltd | Professional & scientific | 2003 |
| Origin Safety Limited | Professional & scientific | 2018 |
| Orr's Meadow Management Company Limited | Households | 2002 |
| OS Mitchell Developments Limited | Construction | 2021 |
| OS Mitchell Estates Limited | Real estate | 2017 |
| OS Mitchell Investments Ltd | Financial services | 2023 |
| Ovington Park (Agriculture) Limited | Agriculture & fishing | 2016 |
| Ovington Park Estates Limited | Financial services | 2015 |
| Ovington Park Estates Rental Ltd | Extraterritorial | 2021 |
| Ovington Park Estates Trading Ltd | Extraterritorial | 2021 |
| Ovington Park Farm Limited | Agriculture & fishing | 1977 |
| Ovington Park Properties 2013 Limited | Real estate | 2013 |
| Ovington Park Properties 2016 Limited | Financial services | 2016 |
| Ovington Park Properties Limited | Agriculture & fishing | 2006 |
| Ovington Park Services LLP | | 2016 |
| OWL Lighting and Controls Limited | Construction | 2024 |
| Oxdrove Farming LLP | | 2026 |
| Pact Dogs Ltd | Professional & scientific | 2021 |
| Paper Rock Publishing Limited | Information & communication | 2015 |
| Papertech Consulting Ltd | Professional & scientific | 2025 |
| Parkbrite Limited | Real estate | 2008 |
| PDM Farming Limited | Agriculture & fishing | 2006 |
| Peak 15 Holdings Ltd | Real estate | 2017 |
| Peak Equestrian Performance Ltd | Arts & recreation | 2018 |
| Peak Equine Performance Ltd | Agriculture & fishing | 2024 |
| Pegasuscroft Limited | Real estate | 1994 |
| Penson Architecture Holdings Limited | Professional & scientific | 2021 |
| Penson Architecture Limited | Professional & scientific | 2012 |
| Penson Events Limited | Arts & recreation | 2015 |
| Penson Family Office Limited | Arts & recreation | 2021 |
| Penson Motorsports LLP | | 2018 |
| PEP Room Consulting Ltd | Professional & scientific | 2021 |
| Peter Marsh Consulting Employee Ownership Trust Limited | Other services | 2021 |
| Peter Marsh Consulting Ltd | Construction | 2011 |
| Peter Wright Consulting Limited | Information & communication | 2024 |
| Pharma Consultancy Group Ltd | Professional & scientific | 2023 |
| Phelps Property Services Limited | Real estate | 2021 |
| Philip Prado Limited | Real estate | 2011 |
| Phoenix Auto Services Limited | Wholesale & retail | 2002 |
| PICCOLA1 Limited | Hospitality | 2026 |