| Multi Trade Supplies Limited | Extraterritorial | 2009 |
| Mulyak Holdings Limited | Professional & scientific | 2008 |
| Muralize Ltd | Manufacturing | 2025 |
| Murlo Plant Hire Limited | Administrative & support | 2017 |
| Murray's Transport (Hants) Limited | Transport & logistics | 2000 |
| MWW Consultancy Limited | Professional & scientific | 2015 |
| My Colony CIC | Education | 2025 |
| My Photo Booth Experience Ltd | Professional & scientific | 2017 |
| Myhealthcareuk Limited | Wholesale & retail | 2025 |
| Mynard Leadwork Ltd | Construction | 2014 |
| N & T Plant Hire Limited | Construction | 2011 |
| N Koranteng Limited | Wholesale & retail | 2016 |
| Nadampur Spice Bar Limited | Hospitality | 2023 |
| Nasec Limited | Information & communication | 2020 |
| Nautical Flooring Limited | Construction | 2026 |
| Navitron Systems Limited | Manufacturing | 1991 |
| NCF Financial Services Ltd | Financial services | 2023 |
| ND Perspective Ltd | Education | 2024 |
| Nd-Nelson Enterprise Ltd | Health & social care | 2012 |
| Neal Player Limited | Administrative & support | 2003 |
| Nebula Paint Products Limited | Manufacturing | 2022 |
| Neria Victer Ltd | Wholesale & retail | 2025 |
| Neutron Stars UK Ltd | Manufacturing | 2023 |
| Nevnet Ltd | Hospitality | 2025 |
| New City Joinery Limited | Construction | 2018 |
| New Horizon Services Limited | Professional & scientific | 2007 |
| New Land Solutions Limited | Information & communication | 2006 |
| Newaromaelixir Ltd | Manufacturing | 2024 |
| Newnham Road Management Company Limited | Households | 2019 |
| News Properties Ipswich Limited | Hospitality | 2024 |
| Newtforce Solutions Ltd | Professional & scientific | 2026 |
| Nexia Security Solutions Ltd | Administrative & support | 2025 |
| Nextgen Construction Ltd | Construction | 2026 |
| Neybr Tech Limited | Information & communication | 2025 |
| Nice Spice Limited | Hospitality | 2026 |
| Nick Edgeller Inside OUT Limited | Administrative & support | 2010 |
| Nickelfix Homes Ltd | Construction | 2019 |
| Niffty Witchy Supplies Limited | Wholesale & retail | 2025 |
| Nightlight Electrical Limited | Construction | 2023 |
| Niki Enterprise Limited | Wholesale & retail | 2015 |
| Nilkhanth Ltd | Wholesale & retail | 2023 |
| Nilssen ENT Services Ltd | Health & social care | 2013 |
| NO Fear Bridge Ltd | Arts & recreation | 2013 |
| Norlau Collection Ltd | Water & waste | 2022 |
| North Star 408 Ltd | Information & communication | 2024 |
| Nourishing Cravings Limited | Hospitality | 2026 |
| Novus Tips Ltd | Manufacturing | 2018 |
| NOW Telecom Limited | Information & communication | 2014 |
| NOX Night Angels Limited | Wholesale & retail | 2025 |
| Npdr Property Ltd | Real estate | 2025 |
| Npdr Solutions Limited | Professional & scientific | 2023 |
| Numbergurus Limited | Information & communication | 2025 |
| Nwan Tech Ltd | Wholesale & retail | 2024 |
| Nyali Bridge Ltd | Transport & logistics | 2020 |
| O5A Limited | Health & social care | 2024 |
| Oak Tree Land Acquisitions Limited | Real estate | 2026 |
| Oakley and Lyburn Holdings Limited | Real estate | 2026 |
| Oakwood Management Company (Havant) Limited | Real estate | 1988 |
| OB Tech Repair Ltd | Manufacturing | 2024 |
| Oberon Performance Limited | Manufacturing | 2005 |
| Obsessed to Success Ltd | Information & communication | 2025 |
| Odena Investments LLP | | 2024 |
| Odlings Limited | Wholesale & retail | 1966 |
| Odlings MCR Limited | Manufacturing | 1966 |
| Odyssey HR Consulting Limited | Administrative & support | 2020 |
| OFF the Record (South East Hampshire) | Health & social care | 1997 |
| Oiram Ltd | Real estate | 2021 |
| Oladab Limited | Real estate | 2026 |
| Olkia Investments Limited | Other services | 1995 |
| OM Fury Limited | Professional & scientific | 2025 |
| OMD Systems Limited | Professional & scientific | 2023 |
| Onboard TV Ltd | Professional & scientific | 2007 |
| Open Accountancy Ltd | Professional & scientific | 2013 |
| Open Ledger Limited | Professional & scientific | 2011 |
| Openran Mobile Ltd | Information & communication | 2024 |
| Opportunity Education Services Ltd | Education | 2014 |
| Optivet Referrals (South London) Ltd | Professional & scientific | 2025 |
| Optivet Referrals Limited | Professional & scientific | 2009 |
| Orbis Systems Limited | Information & communication | 2025 |
| Organic - Aromatherapy Limited | Health & social care | 2009 |
| Oska Care Limited | Wholesale & retail | 2013 |
| OSO Corporation Ltd | Information & communication | 2014 |
| Ottavia Boero Limited | Extraterritorial | 2024 |
| Outpost Projects Ltd | Construction | 2024 |
| Oxalor Limited | Professional & scientific | 2004 |
| P & I Generators Limited | Administrative & support | 2006 |
| P.B. CD Limited | Construction | 2008 |
| Pallant Aesthetics Ltd | Health & social care | 2021 |
| Panda Accounting Services Limited | Professional & scientific | 2014 |
| Paradise Haven 2023 Limited | Hospitality | 2023 |
| Paragon Paving Ltd | Construction | 2025 |
| Parchment Lofts Limited | Administrative & support | 2009 |
| Pario Consulting Limited | Professional & scientific | 2009 |
| Parish Investments Limited | Real estate | 2001 |
| Park Building Services and Property Maintenance Ltd | Construction | 2024 |
| Park Community Enterprises Limited | Manufacturing | 2013 |
| Park Express Limited | Hospitality | 2026 |
| Partnering Energy Limited | Construction | 2022 |
| Partnering Matters Limited | Public administration | 2022 |
| Passion Care PVT Ltd | Administrative & support | 2015 |