| Nedburn Properties Limited | Construction | 1972 |
| Nedzo Properties Limited | Real estate | 2025 |
| Neston Court Limited | Construction | 1983 |
| New Gate Projects Limited | Construction | 2018 |
| Newgate Business Space NO3 Ltd | Real estate | 2021 |
| Newgate Housing Limited | Real estate | 2014 |
| Newton's Building Services (Hertfordshire) Limited | Manufacturing | 2024 |
| Newton's Building Services Limited | Manufacturing | 2017 |
| Newtons Group Limited | Professional & scientific | 2026 |
| Next Step Mortgage Solutions Limited | Financial services | 2016 |
| Nfph Property Limited | Administrative & support | 2013 |
| Ngonga Emergency Limited | Health & social care | 2011 |
| Nicky Cornell Limited | Wholesale & retail | 2010 |
| Nightingale Court Residents Association Limited | Households | 2003 |
| NKB Heating Ltd | Construction | 2021 |
| North Interiors Ltd | Administrative & support | 2002 |
| Norton Estates Limited | Real estate | 1978 |
| Novitas Underwriting Agency Limited | Financial services | 1995 |
| NU Plumbing & Heating Ltd | Construction | 2022 |
| Number Mouse Ltd | Professional & scientific | 2014 |
| O.C. Consulting (UK) Limited | Professional & scientific | 2012 |
| Ocdiagnostics Limited | Wholesale & retail | 2017 |
| Odyssey Pictures Ltd | Professional & scientific | 2015 |
| Olly Croft Centre of Excellence Ltd | Arts & recreation | 2025 |
| Olly Croft Centre of Excellence Specialist Lounge Ltd | Arts & recreation | 2025 |
| Omac Construction Cost Consultants Limited | Construction | 2013 |
| Omni Arts Limited | Extraterritorial | 2006 |
| Omni Martial Arts Limited | Extraterritorial | 2006 |
| One World Asset Management (UK) Limited | Wholesale & retail | 2014 |
| Online Music Limited | Information & communication | 2006 |
| OPS London Ltd | Construction | 2005 |
| Options for Homes MGT Ltd | Construction | 2020 |
| Orchid Kids Club Ltd | Health & social care | 2018 |
| Ordlaus Studios Ltd | Construction | 2019 |
| Orick Engineering Limited | Construction | 2006 |
| Oris 62 Ltd | Hospitality | 2013 |
| OW Services Limited | Construction | 2019 |
| Owens Partnership Limited | Professional & scientific | 2017 |
| Owmy Limited | Wholesale & retail | 2019 |
| Oxford Management Consultants Limited | Professional & scientific | 1980 |
| Oxial UK Limited | Information & communication | 2010 |
| Ozpak (2007) Ltd | Real estate | 2007 |
| P & N Specialist Brickwork Ltd | Construction | 2012 |
| P E Tinsley Builders Limited | Construction | 2003 |
| P&N Plumbing & Heating Ltd | Administrative & support | 2018 |
| Pageprinters Limited | Manufacturing | 2016 |
| Pagos Consultants Limited | Administrative & support | 2017 |
| Paneltech (Kent) Limited | Manufacturing | 2015 |
| Panna Scenery Limited | Construction | 2019 |
| Paris Carpentry Limited | Construction | 2015 |
| Park Place Residents Management Co. Limited | Households | 2005 |
| Parkway (Harlow) Management Limited | Real estate | 2005 |
| PAT Taylor Garden Services Ltd | Administrative & support | 2012 |
| PAT Taylor Groundworks and Concrete Limited | Construction | 2016 |
| Paul Wallace Group LLP | | 2016 |
| PB Contracts (UK) Limited | Construction | 2011 |
| Peelhouse Services Ltd | Administrative & support | 2001 |
| PEJ Restaurants Limited | Hospitality | 2016 |
| Penumbral Consilium Strategic Advisers Ltd | Professional & scientific | 2026 |
| Petre Horvat Ltd | Manufacturing | 2022 |
| PG Minibuses Ltd | Transport & logistics | 2019 |
| Phil Gottschalk Groundworks Limited | Extraterritorial | 2013 |
| Phillips Consult Ltd | Professional & scientific | 2011 |
| Phoenix DG Limited | Construction | 2026 |
| Phonecare 2025 Ltd | Other services | 2025 |
| PIC Construction Services Limited | Construction | 2015 |
| Pickard Close (Chase RD N14) Flat Management Company Limited | Households | 2003 |
| Pinar (UK) Ltd | Other services | 1996 |
| Pinella Limited | Manufacturing | 2000 |
| Piril Sideras Academy Limited | Education | 2025 |
| Pizzeria Bel-Sit Ltd | Hospitality | 2010 |
| PJ GAS Utilities Ltd | Construction | 2023 |
| Place House Management Company Limited | Real estate | 2007 |
| Platinum Flooring Ltd | Construction | 2018 |
| Portvale Accounting Limited | Professional & scientific | 2023 |
| Postern Green Management Company Limited | Households | 1980 |
| Potters Bar Management Company Limited | Households | 2004 |
| Prime Aesthetic Holdings Ltd | Real estate | 2026 |
| Principal Security (London) Limited | Administrative & support | 2024 |
| Propertex 2016 Limited | Real estate | 2016 |
| Property Liaisons (Wapping) Limited | Real estate | 2019 |
| Providence Care Solutions Ltd | Health & social care | 2019 |
| PSI Inbusiness Limited | Professional & scientific | 2016 |
| Puppy Coach Ltd | Professional & scientific | 2016 |
| Purple Raspberry Limited | Hospitality | 2002 |
| Quantum Protection Ltd | Construction | 2025 |
| Quatro Hercules Limited | Transport & logistics | 2006 |
| R & P Gibbs Limited | Construction | 2006 |
| R & S Ventilation Limited | Construction | 2003 |
| R 100 Studios Limited | Information & communication | 2018 |
| R F P Contracting Limited | Construction | 2012 |
| R J B Decorating Limited | Other services | 2014 |
| R J Clarke Brickwork Ltd | Construction | 2021 |
| R&N Reading Property Ltd | Real estate | 2025 |
| Radio Silks Limited | Wholesale & retail | 1933 |
| Rana Property Management Limited | Real estate | 2015 |
| Rapid Tech Limited | Wholesale & retail | 2017 |
| RAW Innovation & Design Ltd | Information & communication | 2018 |
| Raymond Drewry Technology Ltd | Information & communication | 2007 |
| RDT Office Solutions Group Ltd | Administrative & support | 2007 |