| Only Oncology Limited | Professional & scientific | 2016 |
| Onlybetter Limited | Real estate | 1999 |
| Onyx Medica Communications Limited | Professional & scientific | 2016 |
| Opal Developments Ltd | Real estate | 2020 |
| Opallios Limited | Professional & scientific | 2016 |
| Open Consultancy Limited | Professional & scientific | 2018 |
| Openlivespace Limited | Real estate | 2020 |
| Optech Fibres Limited | Construction | 2005 |
| Optimised I T Limited | Other services | 2009 |
| Optimum Project Consultancy Limited | Professional & scientific | 2013 |
| Optimus 5 Limited | Administrative & support | 2015 |
| Orange Insight Ltd | Professional & scientific | 2024 |
| ORB Logistics Ltd | Transport & logistics | 2026 |
| Original Brands Ltd. | Wholesale & retail | 2014 |
| Original Objective Ltd | Information & communication | 2013 |
| Original Pictures Limited | Manufacturing | 2004 |
| Origo Supply Chain Limited | Transport & logistics | 2015 |
| Orlowen Ltd | Professional & scientific | 2021 |
| OSB Digital Limited | Wholesale & retail | 2024 |
| Osborne International Limited | Professional & scientific | 2022 |
| Oscar Charles Ltd | Wholesale & retail | 2017 |
| Osiris 2000 Limited | Real estate | 2020 |
| OTH Group Holdings Ltd | Financial services | 2025 |
| Otis Audiology Ltd | Health & social care | 2020 |
| OUT to Help Children's Services Limited | Education | 2021 |
| Outdoor Heaven Limited | Wholesale & retail | 2000 |
| Outible Ltd | Information & communication | 2018 |
| Outreach Teach Ltd | Education | 2024 |
| Over Tabley Hall Farm Limited | Households | 2018 |
| Owen House Wedding Barn Limited | Other services | 2002 |
| OWL Consulting Projects Limited | Administrative & support | 2022 |
| OWL Consulting Services Limited | Administrative & support | 2016 |
| OWL Property Developments and Lettings Ltd | Real estate | 2016 |
| Ownpower Renewable Energy Development Ltd | Professional & scientific | 2014 |
| Ownpower Renewables Ltd | Professional & scientific | 2013 |
| Ownpower(Cheshire) Ltd | Construction | 2008 |
| Oxygen Rentals Limited | Real estate | 2026 |
| OYT Properties Limited | Real estate | 2022 |
| P & S Kitchens Limited | Wholesale & retail | 2011 |
| P Foster Limited | Administrative & support | 2025 |
| P G Publications Limited | Arts & recreation | 2004 |
| P L S (Remedial Services) Limited | Construction | 1995 |
| P R D Business Consultants Limited | Professional & scientific | 2015 |
| P&P Partnership Ltd | Wholesale & retail | 2020 |
| P. & M. Timmis (Services) Limited | Education | 1988 |
| P.A. Ross Food Ltd | Wholesale & retail | 2016 |
| P.A. Ross Holdings Ltd | Financial services | 2016 |
| P.A. Ross Ltd | Wholesale & retail | 1997 |
| P85 Holdings Ltd | Financial services | 2025 |
| P85 Investmentco Limited | Financial services | 2025 |
| Pack Software Limited | Information & communication | 2018 |
| Paddle Point Ltd | Arts & recreation | 2025 |
| Padel 500 Limited | Arts & recreation | 2026 |
| Padmore Education Limited | Education | 2020 |
| Paisley Property Development Ltd | Construction | 2014 |
| Palimpsest Development Ltd | Administrative & support | 2023 |
| Pan-Optic Monitoring Limited | Extraterritorial | 2013 |
| Panacea 85 Ltd | Administrative & support | 2015 |
| Panacea Solutions Limited | Professional & scientific | 2020 |
| Pandemonium Holdings Ltd | Financial services | 2023 |
| Panoramic Properties Limited | Construction | 2010 |
| Parabellum Events Limited | Other services | 2022 |
| Parabellum Protection Limited | Administrative & support | 2021 |
| Paragon Medica Limited | Professional & scientific | 2016 |
| Paraplus (Holdings) Limited | Administrative & support | 2010 |
| Parent NAV Ltd | Health & social care | 2025 |
| Park Hall Hospitality Ltd | Hospitality | 2022 |
| Park Hall Supported Living Ltd | Health & social care | 2022 |
| Park Modern Properties Limited | Real estate | 2026 |
| Parker Prestige Services Limited | Transport & logistics | 2024 |
| Parkfield Road Estates Limited | Construction | 2010 |
| Parkgate Engineering Ltd | Professional & scientific | 2012 |
| Parkgate Estate Ltd | Real estate | 2026 |
| Parkgate Fencing & Gates Ltd | Construction | 2021 |
| Parkgate Oriental Ltd | Hospitality | 2025 |
| Parkgate Rentals Limited | Real estate | 2018 |
| Parkgate Tyres and MOT Limited | Wholesale & retail | 2016 |
| Pastest Limited | Information & communication | 2000 |
| Patron (BC) Bidco Limited | Professional & scientific | 2017 |
| Patternit Ltd | Information & communication | 2010 |
| Patterns and Plains Ltd | Wholesale & retail | 2018 |
| Paul Benny Limited | Professional & scientific | 2017 |
| Paul Latu-Andrews Ltd | Wholesale & retail | 2021 |
| Paul Lockton Limited | Other services | 2017 |
| Paul Sharples Furniture Limited | Real estate | 1996 |
| Paveyisla Properties Ltd | Real estate | 2026 |
| Pawan Endoscopy Limited | Health & social care | 2016 |
| Paws Direct Limited | Professional & scientific | 2011 |
| Pawsome Biotics Ltd | Wholesale & retail | 2023 |
| PB Maintenance Limited | Construction | 2023 |
| PDP Contracting Limited | Agriculture & fishing | 2012 |
| PDS Resourcing Limited | Administrative & support | 2008 |
| Peak Living Properties Limited | Real estate | 2022 |
| Peak Performance Advertising Ltd | Professional & scientific | 2020 |
| Peak Power Gym Limited | Arts & recreation | 2021 |
| Peak Power Sports Ltd | Arts & recreation | 2024 |
| Peak Real Estate Ltd | Real estate | 2022 |
| Pearson Homes Knutsford Limited | Real estate | 2018 |
| Pelean UK Limited | Financial services | 2024 |
| Pen-Y-Glol Holidays Limited | Hospitality | 2024 |