| Oddyns Properties Ltd | Real estate | 2013 |
| Odonate Ltd | Information & communication | 2020 |
| Ogden-Gould Consulting Limited | Professional & scientific | 2024 |
| OJ1 Limited | Information & communication | 2024 |
| Okkayd Ltd | Professional & scientific | 2025 |
| Old Bear House Management Limited | Households | 2024 |
| Old Hall Enterprises Limited | Transport & logistics | 1985 |
| Old MAN JR. Ltd | Arts & recreation | 2025 |
| Old School Gaming Ltd | Manufacturing | 2025 |
| OM Namah Homes Ltd | Real estate | 2024 |
| Omega Volt Limited | Construction | 2026 |
| OMH Solutions Limited | Real estate | 2017 |
| Omnibus Global Theatre Company Limited | Administrative & support | 2024 |
| ON Film Limited | Administrative & support | 2013 |
| ON SET Productions Ltd | Transport & logistics | 2019 |
| One Over Ltd | Hospitality | 2023 |
| One Stop Consultancy Services Ltd | Manufacturing | 2017 |
| Onefan Limited | Information & communication | 2019 |
| Onpoint Personal Training Limited | Arts & recreation | 2014 |
| Onset Branding Limited | Professional & scientific | 2024 |
| Operae Consulting Limited | Professional & scientific | 2014 |
| Opticomm Media Ltd | Professional & scientific | 2022 |
| Optimir Limited | Information & communication | 2024 |
| Optrak Distribution Software Limited | Information & communication | 1988 |
| Orbita Collective Ltd | Professional & scientific | 2025 |
| Orion Creations Ltd | Manufacturing | 2024 |
| Oriondome Limited | Real estate | 1998 |
| OSM Windows Limited | Construction | 2022 |
| Osteo-Flow Ltd | Health & social care | 2023 |
| Outfox Escape Games Limited | Arts & recreation | 2019 |
| Outlaw Entertainments Ltd | Agriculture & fishing | 2023 |
| Outside the Box Education Ltd | Education | 2010 |
| Ovelo Ltd | Information & communication | 2025 |
| Own Your REP Limited | Professional & scientific | 2026 |
| P & C Lowry Limited | Real estate | 2017 |
| P J Healy Ltd | Manufacturing | 2007 |
| P&F Adventures Ltd | Arts & recreation | 2024 |
| P.Bowman Limited | Real estate | 2018 |
| P.R. Hedges Electrical Ltd | Construction | 2017 |
| P.R.S. Group Construction Ltd | Construction | 2025 |
| Page Hill Properties Limited | Real estate | 2019 |
| Page Studio Limited | Professional & scientific | 2023 |
| Pakkiyam PVT Ltd | Wholesale & retail | 2019 |
| Panna.Reworks Ltd | Wholesale & retail | 2025 |
| Papillon Consulting Services Ltd. | Information & communication | 2018 |
| Parker Bros - Property Hoes Ltd | Real estate | 2026 |
| Parker Developments Limited | Real estate | 2000 |
| Parker's Jewellers & Goldsmiths Limited | Wholesale & retail | 2006 |
| Parkertecture Ltd | Professional & scientific | 2023 |
| Parklanesuppliers Ltd | Construction | 2026 |
| Parsell Holdings Limited | Financial services | 2025 |
| Part Two Ltd | Professional & scientific | 2022 |
| Patient Centric Sampling Interest Group CIC | Health & social care | 2023 |
| Paul Bowman Life Coaching Ltd | Health & social care | 2026 |
| Paul Bowman Personal Training Ltd | Arts & recreation | 2026 |
| Paul Oliver Limited | Administrative & support | 2003 |
| Paul Staples Coaching Limited | Professional & scientific | 2022 |
| Paulscapes Ltd | Administrative & support | 2023 |
| Paxman Holdings Limited | Financial services | 1983 |
| PAY Wise Limited | Other services | 2023 |
| Payday Clothing Limited | Wholesale & retail | 2023 |
| PB Training Limited | Education | 2026 |
| PCC International Ltd | Professional & scientific | 2003 |
| Peacock Wealth Management Ltd | Financial services | 2014 |
| Pebble IT Limited | Information & communication | 2024 |
| Peerglow Asset Limited | Energy | 2014 |
| Peerglow Group Limited | Professional & scientific | 2015 |
| Pelican Hill Capital Management Ltd | Transport & logistics | 2024 |
| Pelican Options Ltd | Information & communication | 2015 |
| Penwood Property Limited | Real estate | 2019 |
| Perception Systems Limited | Information & communication | 2020 |
| Perfectly Clean BUT Simple Limited | Administrative & support | 2019 |
| Performance Wellbeing and Safeguarding Limited | Professional & scientific | 2021 |
| Performance Wellbeing Services Limited | Professional & scientific | 2022 |
| Perlini Property Maintenance Ltd | Construction | 2025 |
| Permalogical Ltd | Agriculture & fishing | 2014 |
| Perowne Trading Limited | Financial services | 2025 |
| Pest Pro Solutions Limited | Administrative & support | 2024 |
| Peter Cuffaro Estate Agents Ltd | Real estate | 2022 |
| Peter Hembrough Bows Ltd | Wholesale & retail | 2024 |
| Peter Suggett Consultancy Ltd | Administrative & support | 2020 |
| PFC Cleaning Services Ltd | Administrative & support | 2026 |
| Phil-Ease Ltd | Wholesale & retail | 2022 |
| Pierides Bros Ltd | Professional & scientific | 2019 |
| Pierides Consultancy Ltd | Professional & scientific | 2026 |
| Pilotclass (Kero) Limited | Wholesale & retail | 2001 |
| Pineview Stansted Limited | Construction | 2011 |
| Pineview Thaxted Limited | Construction | 2010 |
| Pinewood School Academy Trust | Education | 2014 |
| Pinkneys Homes Ltd | Real estate | 2023 |
| Pipeline Bathrooms Limited | Construction | 2015 |
| Pipes Limited | Construction | 2003 |
| Piql UKI Ltd | Information & communication | 2025 |
| Piscaries Limited | Agriculture & fishing | 2023 |
| Pivot-Dc Ltd | Information & communication | 2024 |
| Pizza & Pale ALE Ltd | Professional & scientific | 2020 |
| PJB Planning Ltd | Professional & scientific | 2020 |
| PJD PPM Limited | Professional & scientific | 2017 |
| PJD Projects Limited | Financial services | 2014 |
| Plainview Ventures Limited | Information & communication | 2015 |