| Nuovo Italia Property Ltd | Real estate | 2024 |
| Nurjahan Foods Limited | Hospitality | 2022 |
| Nursey Group Ltd | Professional & scientific | 2020 |
| Nuttall Equestrian Limited | Agriculture & fishing | 2013 |
| Nvcatering Ltd | Administrative & support | 2019 |
| NW the Female Decorator Ltd | Construction | 2025 |
| O & H Removals Limited | Transport & logistics | 2006 |
| Oak Hearts Home Renovations Ltd | Construction | 2013 |
| Oak Ridge Park (Management) Limited | Real estate | 1999 |
| Oaklands Day Nursery Ltd | Health & social care | 2023 |
| Octavo Direct Image Limited | Manufacturing | 2000 |
| Oddies Country Living Ltd | Administrative & support | 2011 |
| Ogilvie Thorne Limited | Professional & scientific | 2020 |
| Oiseau Vert Ltd | Real estate | 2021 |
| Old Mill Accountancy 2021 LLP | | 2006 |
| Old Mill Accountancy Limited | Professional & scientific | 2021 |
| Old Mill Audit Limited | Professional & scientific | 2021 |
| Old Mill Financial Planning Limited | Financial services | 2021 |
| Old Mill Jackson Limited | Professional & scientific | 2006 |
| Old Mill Topco Limited | Financial services | 2021 |
| Old Mill Trust Corporation Limited | Professional & scientific | 2017 |
| Olive & Honey Events Ltd | Hospitality | 2025 |
| Olive Farm (Babcary) Limited | Agriculture & fishing | 1977 |
| Olubanji Oguntunde Services Limited | Health & social care | 2022 |
| OMC Electrical Ltd | Construction | 2018 |
| Online Golf Media LLP | | 2012 |
| Online Offie Limited | Wholesale & retail | 2015 |
| Opal Tennis Ltd | Arts & recreation | 2026 |
| Open Door Designs Limited | Administrative & support | 2009 |
| Open Mart Online Limited | Wholesale & retail | 2025 |
| Open Mouth Productions Limited | Information & communication | 2009 |
| Opium Holdings Limited | Financial services | 2016 |
| Opium Power Limited | Energy | 2018 |
| Optimal Talent Group Limited | Arts & recreation | 2021 |
| Optimum Construction Limited | Construction | 2003 |
| Opzet Ltd | Wholesale & retail | 2025 |
| Orchard Enterprises (Oldbury 1946) Limited | Administrative & support | 2003 |
| Orchard Gymnastics Limited | Arts & recreation | 2009 |
| Orchid Productions Limited | Information & communication | 2026 |
| Orci Limited | Arts & recreation | 2004 |
| Ornico Property Solutions Ltd | Extraterritorial | 2025 |
| OS Nueby Properties Ltd. | Real estate | 2023 |
| Osec Defense Ltd | Information & communication | 2025 |
| Osirius Auto Limited | Wholesale & retail | 2023 |
| Otto Direct Ltd | Wholesale & retail | 2026 |
| OUR Lobster Limited | Wholesale & retail | 2021 |
| Ourstayaway Ltd | Construction | 2022 |
| Overt Locke Limited | Wholesale & retail | 1998 |
| Ovoo Ltd | Transport & logistics | 2019 |
| P & C Decorators Limited | Construction | 1997 |
| P & S Cullen Ltd | Real estate | 2023 |
| P & V Minibuses Ltd | Transport & logistics | 2026 |
| P a Safety Services Limited | Professional & scientific | 2007 |
| P a Vine & SON Ltd | Construction | 2018 |
| P and a Sales and Lettings Limited | Real estate | 2014 |
| P and J Dyer Limited | Agriculture & fishing | 2011 |
| P Cubed Projects Ltd | Construction | 2023 |
| P D Ford Carpets Limited | Wholesale & retail | 2005 |
| P D Noake Limited | Construction | 2009 |
| P Dunford Enterprises Ltd | Information & communication | 2025 |
| P I Civils Ltd | Construction | 2018 |
| P J Fire Safety Consultants Limited | Financial services | 2018 |
| P Slade Investments Limited | Real estate | 2005 |
| P.A.Dentservices Ltd | Health & social care | 2022 |
| P.M.W. Commercials Limited | Transport & logistics | 1989 |
| P.S. Logistics (UK) Ltd | Transport & logistics | 2004 |
| Pablo's Pantry Ltd | Manufacturing | 2025 |
| Pabullion Limited | Wholesale & retail | 2024 |
| Pakobazaar Ltd | Wholesale & retail | 2020 |
| Palmer & Bishop Limited | Construction | 1958 |
| Palmers Catering Limited | Hospitality | 1976 |
| Palmers Trading Estates (Preston) Limited | Wholesale & retail | 1992 |
| Pamil Limited | Health & social care | 2017 |
| Panalangin Ltd | Health & social care | 2016 |
| Papa Kilo Management Ltd | Professional & scientific | 2012 |
| Papergreat Limited | Real estate | 2000 |
| PAR Holdings Limited | Professional & scientific | 1968 |
| Park (Fifteen) Residents Limited | Households | 2000 |
| Parkmatic Consulting Limited | Information & communication | 2018 |
| Parko Retails Limited | Wholesale & retail | 2026 |
| Parkway Professional Services Limited | Administrative & support | 2007 |
| Parth Ltd | Professional & scientific | 2019 |
| Past Participate C.I.C. | Professional & scientific | 2018 |
| Path Marketing Limited | Information & communication | 2014 |
| Paul Price Stores (UK) Limited | Wholesale & retail | 2003 |
| Paul Rowe Design Services Limited | Professional & scientific | 2025 |
| Paul Street Taunton Limited | Real estate | 2023 |
| Pavyotts Mill Fisheries Limited | Other services | 2021 |
| Paws N Klaws Limited | Other services | 2024 |
| Paxton Property Management Ltd | Real estate | 2026 |
| Payroll Clapton Limited | Administrative & support | 2023 |
| Payroll Ponsford Street Limited | Administrative & support | 2023 |
| Payroll Victoria Park Limited | Administrative & support | 2023 |
| PCA Haulage Limited | Transport & logistics | 2021 |
| PCA Mechanical and Electrical Limited | Professional & scientific | 2021 |
| PDQ Precision Limited | Professional & scientific | 2011 |
| Pear Appreciate Life Ltd | Wholesale & retail | 2021 |
| Peckmoor Farming Limited | Agriculture & fishing | 1996 |
| Pegasus Aviation Safety Services Ltd | Professional & scientific | 2025 |
| Peking House Gallery Limited | Hospitality | 2024 |