| Oskar Wash & Valet Ltd | Administrative & support | 2026 |
| OTB (Wales) Consulting Ltd | Construction | 2011 |
| Ouija Ltd | Hospitality | 2019 |
| OUT of Space Design & Build Limited | Professional & scientific | 2018 |
| Outside in Collaboration UK Ltd | Information & communication | 2013 |
| Ovalacre Limited | Extraterritorial | 2026 |
| Ovaldean Limited | Information & communication | 2024 |
| Ovalmaid Limited | Extraterritorial | 2025 |
| Ovalmain Limited | Extraterritorial | 2025 |
| Ovalmead Limited | Extraterritorial | 2026 |
| Ovalmore Limited | Information & communication | 2025 |
| Ovalpine Limited | Extraterritorial | 2025 |
| Oven Craft Limited | Administrative & support | 2016 |
| Overdale Construction Services Limited | Construction | 2001 |
| Overdale Properties (South Wales) Limited | Real estate | 1999 |
| Overdale Steels Ltd | Construction | 2021 |
| Overmore Limited | Information & communication | 2024 |
| Overmoss Limited | Extraterritorial | 2026 |
| Overseas Support Limited | Information & communication | 2024 |
| Overwynn Limited | Wholesale & retail | 2025 |
| Owen Holland (Engineering) Limited | Manufacturing | 1965 |
| Owen's Dairies Limited | Wholesale & retail | 2009 |
| Owlvue Ltd | Wholesale & retail | 2017 |
| Oxford House Menswear Ltd | Wholesale & retail | 2007 |
| OZ Brother's Property Ltd | Real estate | 2023 |
| OZ Brothers Ltd | Hospitality | 2016 |
| Ozcoms Limited | Transport & logistics | 2025 |
| P & D Kinsella Properties Limited | Real estate | 2023 |
| P & I Fabrications Limited | Administrative & support | 2010 |
| P & L Strategies Limited | Financial services | 2025 |
| P R Logistics and Warehousing Limited | Transport & logistics | 2021 |
| P T Contracting Ltd | Transport & logistics | 2025 |
| P&F Recovery Ltd | Wholesale & retail | 2021 |
| P&Hf Consulting Limited | Professional & scientific | 2024 |
| P. C. Signs Limited | Manufacturing | 2016 |
| P. D. Morgan Limited | Manufacturing | 1999 |
| P.B.M Wales Holdings Ltd | Financial services | 2026 |
| P.C.M. Drainage Ltd | Water & waste | 2024 |
| P.D. Morgan (Holdings) Limited | Professional & scientific | 2007 |
| P.G.W Property Maintenance Limited | Construction | 2018 |
| P.M.A. Enterprises Ltd | Wholesale & retail | 2025 |
| P.S.S. Scaffolding Ltd | Construction | 2002 |
| P3 Office Ltd | Professional & scientific | 2022 |
| PAD Brickwork Ltd | Construction | 2022 |
| Padge Music Ltd | Wholesale & retail | 2023 |
| Pads 4 U Limited | Construction | 2022 |
| Painttechnics Holdings Limited | Wholesale & retail | 2024 |
| Paladin Games Ltd | Wholesale & retail | 2026 |
| Pallister Clothing 1969 Limited | Wholesale & retail | 2024 |
| Palomar Research Ltd | Professional & scientific | 2018 |
| Panamkuzha Ltd | Health & social care | 2016 |
| Pandy Farm Limited | Agriculture & fishing | 2020 |
| Pannell Lighting Limited | Construction | 2018 |
| Paragon Tecnnology Consulting Ltd | Information & communication | 2023 |
| Parameter Design Limited | Professional & scientific | 2003 |
| Parc Dyffryn Limited | Energy | 2025 |
| Parc Stormy Ltd | Real estate | 2021 |
| Park Street Surgery Ltd | Health & social care | 2016 |
| Park Tree Homes Ltd | Construction | 2018 |
| Parkclass Limited | Construction | 1992 |
| Parkes Skin Clinic Limited | Health & social care | 2021 |
| Parkfields Road Management Company Limited | Extraterritorial | 2011 |
| Parkland Stoves Limited | Wholesale & retail | 2023 |
| Parklands Dental Practice Ltd | Health & social care | 2017 |
| Parkview HR Ltd | Administrative & support | 2020 |
| Parpubs Ltd | Hospitality | 2024 |
| Partbest Limited | Extraterritorial | 2025 |
| Partcote Limited | Extraterritorial | 2026 |
| Partneriaeth Asbri CYF | Construction | 2019 |
| Party Britain Limited | Wholesale & retail | 2009 |
| Passlink Limited | Extraterritorial | 2025 |
| Passmere Limited | Extraterritorial | 2025 |
| Passwynn Limited | Extraterritorial | 2025 |
| Patholeg Diagnostic Services Ltd | Health & social care | 2021 |
| Pathway to Wellness Ltd | Health & social care | 2025 |
| Pathways Social Work Ltd | Wholesale & retail | 2023 |
| Patsy Property & Consultancy Ltd | Real estate | 2020 |
| Paul Lawrence Intentions Limited | Professional & scientific | 2008 |
| Paul Lowden Tree Surgeon Ltd | Agriculture & fishing | 2019 |
| Paul Smith Manufacturing Services Ltd | Professional & scientific | 2025 |
| Paul Williams Financial Services Limited | Financial services | 2011 |
| Paul's Airport CAB Ltd | Transport & logistics | 2024 |
| Paula Clement Independent Mortgage & Protection Adviser Ltd | Financial services | 2021 |
| Pavin Court Limited | Real estate | 2009 |
| Pawd Consultancy Ltd | Professional & scientific | 2023 |
| PB Security Ltd | Administrative & support | 2018 |
| Pbxrb Logistics Ltd | Transport & logistics | 2026 |
| PC Electronics Ltd | Professional & scientific | 2017 |
| PCM Business Improvement Limited | Professional & scientific | 2008 |
| PCR Estates Ltd | Real estate | 2024 |
| PCT Pubs and Inns Limited | Hospitality | 2025 |
| PDC and Company Plumbing and Heating Ltd | Construction | 2026 |
| PDP Global Ltd | Administrative & support | 2016 |
| PE Education LLP | | 2023 |
| Peak Form Academy Ltd. | Education | 2025 |
| Peak Precision Blasting Limited | Construction | 2021 |
| Peak Supps Limited | Wholesale & retail | 2016 |
| Peakcade Limited | Extraterritorial | 2026 |
| Peakfell Limited | Extraterritorial | 2022 |
| Pearce & Tarr Consulting Limited | Financial services | 2004 |