| Nourish & Move Ltd | Health & social care | 2020 |
| Novavox Media Limited | Information & communication | 2026 |
| November House Construction Ltd | Construction | 2018 |
| Numentica UK Ltd | Information & communication | 2025 |
| Nump Limited | Wholesale & retail | 2025 |
| Nurture & Bloom Childcare Ltd | Health & social care | 2026 |
| Nuvera Studios Ltd | Construction | 2026 |
| NYA Motors Ltd | Wholesale & retail | 2021 |
| O Briain Consultancy Ltd | Administrative & support | 2016 |
| O.M.I Import & Export Limited | Wholesale & retail | 2015 |
| Oaks Sports Centre Limited | Arts & recreation | 1972 |
| Oasis Property Creations Ltd | Real estate | 2021 |
| Ocean RAY Ltd | Wholesale & retail | 2015 |
| Octa Automotive Ltd | Wholesale & retail | 2026 |
| Odds on TV Ltd | Real estate | 2020 |
| Officecleaners Ltd | Information & communication | 2008 |
| Ohmega Services Ltd | Construction | 2018 |
| OJO Transport Limited | Transport & logistics | 2022 |
| Olacorban Ltd | Health & social care | 2022 |
| Old Mill Road Minimarket Ltd | Wholesale & retail | 2019 |
| Olive Branch Care Ltd | Health & social care | 2018 |
| Olive Connect Limited | Wholesale & retail | 2025 |
| Olive Management Limited | Professional & scientific | 2024 |
| OM Sakthi Amma Kaappakam | Health & social care | 2024 |
| ON Balance Accounting Ltd | Professional & scientific | 2015 |
| One Stop Accounting Services Ltd | Professional & scientific | 2015 |
| One Stop Business Centre Limited | Real estate | 1989 |
| One Stop International Limited | Extraterritorial | 2017 |
| One Vision International Solutions Limited | Other services | 2019 |
| Onetech Repairs Ltd | Wholesale & retail | 2021 |
| Onetech Solutions Ltd | Wholesale & retail | 2014 |
| Online Opes Ltd | Information & communication | 2024 |
| Onmap Trading Limited | Wholesale & retail | 2020 |
| Ontrack Tutoring Ltd | Education | 2025 |
| Ooki Ltd | Information & communication | 2024 |
| Ootru Ltd | Real estate | 2026 |
| Opencube Group Ltd | Information & communication | 2023 |
| Optimal Combat Limited | Other services | 2023 |
| Optimise Again Ltd | Health & social care | 2026 |
| Orchard Childcare Limited | Professional & scientific | 2013 |
| Ore-Lou Training & Development Ltd | Education | 2019 |
| Oreofeoluwa Titomi Gbekele (UK) Limited | Professional & scientific | 2000 |
| Original Peri Peri Chicken Limited | Hospitality | 2016 |
| Ortus Recruitment Ltd | Administrative & support | 2020 |
| Osako Limited | Transport & logistics | 2025 |
| Oscar Property Group Ltd | Real estate | 2020 |
| Oscar's Organics Limited | Manufacturing | 2013 |
| OSM Pipework Ltd | Construction | 2023 |
| Osteopathic Educational Services Limited | Education | 2013 |
| Otio Entertainments UK Ltd | Information & communication | 2022 |
| Otio Properties Limited | Construction | 2024 |
| Oval & Circle Limited | Health & social care | 2018 |
| Oval Advisory Limited | Professional & scientific | 2022 |
| Oximis Aesthetic Ltd | Other services | 2024 |
| Ozkok Limited | Hospitality | 2019 |
| Ozone Controls Ltd | Construction | 2025 |
| P & R Residential Ltd | Real estate | 2021 |
| P Grady Electrical Ltd | Construction | 2012 |
| P K Mechanical Limited | Administrative & support | 2019 |
| P&G Construction Ltd | Construction | 2021 |
| P&G Heating and Plumbing Ltd | Construction | 2020 |
| P&J Rigging Limited | Professional & scientific | 2024 |
| P.W. Merkle Limited | Wholesale & retail | 1938 |
| Palmyra Palm Limited | Wholesale & retail | 2022 |
| PAM Management Ltd | Construction | 2021 |
| Panalytix Limited | Information & communication | 2024 |
| Panbear Ltd. | Real estate | 2015 |
| Pangaea Investments Ltd | Real estate | 2019 |
| Papa Jones MS Limited | Hospitality | 2005 |
| Parallel Learning Trust | Education | 2013 |
| Parchmore Court Freehold Limited | Extraterritorial | 2009 |
| Parchmore Limited | Real estate | 2022 |
| Park Hill 2010 Limited | Households | 2010 |
| Park Kitchen Ltd | Hospitality | 2025 |
| Parker Nicholas Ltd | Transport & logistics | 2007 |
| Parker Properties Investment Ltd | Real estate | 2018 |
| Parkgate Secretaries Limited | Professional & scientific | 2000 |
| Parkinson-Thake Properties Limited | Real estate | 2022 |
| Parkside Veterinary Centre Limited | Professional & scientific | 2010 |
| Partridge Heating &Plumbing Ltd | Construction | 2026 |
| Pass Global Limited | Education | 2021 |
| Pass K Limited | Real estate | 2023 |
| Patridge Developments Limited | Construction | 2006 |
| Paul Reed Office & School Furniture Installations Ltd | Transport & logistics | 2025 |
| Paul. T Cabling Services Limited | Professional & scientific | 2015 |
| PAV & JO Builders Limited | Construction | 2016 |
| PAV Heating and Plumbing Ltd | Construction | 2019 |
| PB Materials Hardware Store Carshalton Ltd | Wholesale & retail | 2016 |
| PB Rail Ltd | Professional & scientific | 2020 |
| PBK Financial Services Ltd | Professional & scientific | 2019 |
| PC and MAC Services Ltd | Other services | 2021 |
| PCG Solutions Ltd | Administrative & support | 2021 |
| PCO Rentals Plus Ltd | Administrative & support | 2024 |
| Peach Blossom Boutique Ltd | Wholesale & retail | 2015 |
| Peachestree Ltd | Health & social care | 2023 |
| Peak Performance Training Club Ltd | Arts & recreation | 2020 |
| Pearl & Prism Ltd | Wholesale & retail | 2025 |
| Pearl China Ltd | Hospitality | 2018 |
| Pegasus Solicitors Limited | Professional & scientific | 2014 |
| Pentagram AI Limited | Real estate | 2021 |