| Owen Square Community Energy Ltd | Energy | 2016 |
| Owen-Thomas Construction Ltd | Construction | 2022 |
| Owgsstore Ltd | Wholesale & retail | 2025 |
| OWL (Asset Management) Ltd | Other services | 2026 |
| OWL Immigration Ltd | Other services | 2021 |
| OWL on the Roof Theatre C.I.C. | Arts & recreation | 2022 |
| OWL With a Spark Ltd | Professional & scientific | 2025 |
| Owlise Software Limited | Information & communication | 2018 |
| OWM Holdco Limited | Financial services | 2024 |
| Own Communications Ltd | Professional & scientific | 2018 |
| OWT Studio Ltd. | Information & communication | 2021 |
| Owta Limited | Administrative & support | 1999 |
| OX Estates Ltd | Information & communication | 2014 |
| Oxalis Design Ltd | Professional & scientific | 2022 |
| Oxbode Properties LLP | | 2011 |
| Oxbow Analytics Limited | Professional & scientific | 2022 |
| Oxbristol Ltd | Hospitality | 2026 |
| Oxford AI Academy Ltd | Information & communication | 2025 |
| Oxford Book-Keeping Services Limited | Professional & scientific | 2009 |
| Oxford Coaching Associates Limited | Professional & scientific | 2023 |
| Oxford Education Labs Limited | Information & communication | 2024 |
| Oxford Geo-Social Technologies Limited | Information & communication | 2012 |
| Oxford Global Courses Ltd | Education | 2025 |
| Oxford Road TAP Limited | Hospitality | 2022 |
| Oxford Trade Services Ltd | Construction | 2026 |
| Oxhouse Software Limited | Information & communication | 2017 |
| Oxide Software Ltd | Information & communication | 2017 |
| Oxlyers Travel Limited | Administrative & support | 2018 |
| Oxwich Capital Management Limited | Information & communication | 2002 |
| Oxwich Limited | Information & communication | 1995 |
| Oxygen Fund Data Specialists Ltd | Information & communication | 2020 |
| Oxygen Therapy Limited | Health & social care | 2023 |
| OY Storage & Warehousing Limited | Transport & logistics | 2023 |
| Oyenike Gold Ltd. | Wholesale & retail | 2021 |
| Oyisco Empowerment Limited | Administrative & support | 2020 |
| Oyster Electrical & Data Ltd | Construction | 2024 |
| Oyster Homes Ltd | Construction | 2021 |
| Oyster Property Management Ltd | Real estate | 2026 |
| Oyster Tank Road Freehold Ltd | Households | 2023 |
| OZ Express Limited | Hospitality | 2017 |
| OZ Vascular Limited | Health & social care | 2024 |
| Ozkul Limited | Hospitality | 2007 |
| Ozone Commercial Cleaning Group Limited | Administrative & support | 2018 |
| Ozone Online Store Ltd | Wholesale & retail | 2021 |
| Oztech Limited | Administrative & support | 2014 |
| Oztre Ltd | Real estate | 2020 |
| Ozuki Ltd | Information & communication | 2011 |
| Ozzu Limited | Hospitality | 2020 |
| Ozzy Estates Limited | Real estate | 2021 |
| O`Neill & Co (South West) Limited | Construction | 2007 |
| O’Loughlin Property Limited | Real estate | 2020 |
| O’Sullivan Management Services Ltd | Construction | 2023 |
| P & a Consulting (Bristol) Limited | Administrative & support | 2009 |
| P & B Properties (South West) Limited | Real estate | 2007 |
| P & D Delivery Ltd | Transport & logistics | 2026 |
| P & D Holdings (SW) Limited | Financial services | 2026 |
| P & D Manufacturing Limited | Manufacturing | 1995 |
| P & G Media Limited | Information & communication | 2006 |
| P & H Healthcare Ltd | Health & social care | 2010 |
| P & J Healthcare Limited | Health & social care | 2018 |
| P & J Vallance Limited | Real estate | 2022 |
| P & O Engineering Services Ltd | Professional & scientific | 2005 |
| P & P Duct Erectors Limited | Construction | 2000 |
| P & S Accommodation Limited | Administrative & support | 2004 |
| P & S FOX Interiors Limited | Construction | 2019 |
| P & T Property Holdings Limited | Real estate | 2025 |
| P & T Property Partnership Ltd | Real estate | 2026 |
| P a Fencing Holdings Limited | Financial services | 2025 |
| P a Fencing Limited | Administrative & support | 2002 |
| P a General Building Services Limited | Construction | 2021 |
| P a Testing Services Ltd | Construction | 2015 |
| P and C Investment Properties Limited | Real estate | 2018 |
| P and F Integrated Solutions Ltd | Transport & logistics | 2025 |
| P B Accountancy Limited | Professional & scientific | 2000 |
| P B Evergreen Ltd | Financial services | 2021 |
| P B Prosperity Ltd | Real estate | 2019 |
| P Barnes Consulting Ltd | Administrative & support | 2014 |
| P Collins Ltd | Construction | 2024 |
| P Cooper Plastering and Screeding Limited | Construction | 2018 |
| P Cordingley Ltd | Construction | 2015 |
| P D Bristol PUB Company Limited | Hospitality | 2022 |
| P Distribution Ltd | Transport & logistics | 2017 |
| P Elliott Ltd | Construction | 2021 |
| P F Nelms Ltd | Information & communication | 2017 |
| P F Stoves Limited | Administrative & support | 2019 |
| P G & G Building Services Limited | Financial services | 2008 |
| P G Properties Limited | Real estate | 1998 |
| P H Construction Property Developments Ltd | Construction | 2023 |
| P Hammond Consulting Ltd | Information & communication | 2007 |
| P Hope Construction Ltd | Construction | 2014 |
| P J Daly Properties Ltd | Real estate | 2018 |
| P J Blake Associates Limited | Professional & scientific | 2014 |
| P J Byrne Transport Limited | Transport & logistics | 2009 |
| P J Dyke Paving & Groundwork Ltd | Construction | 2004 |
| P J Grant Window Cleaning Ltd | Professional & scientific | 2003 |
| P J Hill (Building Contractors) Ltd | Construction | 2008 |
| P J Howse Limited | Construction | 2003 |
| P J J Installations Ltd | Construction | 2014 |
| P J Mcnama Limited | Construction | 2002 |
| P J Price Limited | Construction | 2001 |