| Owen Robinson Solutions Limited | Construction | 2024 |
| Owen Thompson Consulting Limited | Professional & scientific | 2024 |
| Owendale Advisory Limited | Information & communication | 2025 |
| Owia Media Ltd | Professional & scientific | 2026 |
| OWL and Jest Ltd | Wholesale & retail | 2025 |
| Owlio Limited | Wholesale & retail | 2024 |
| Owltex LP | | 2018 |
| OX Global Sports & Media Ltd | Financial services | 2026 |
| OX GP 1 Limited | Administrative & support | 2020 |
| OX GP LLP | | 2020 |
| OX SLP LP | | 2020 |
| OX Tennis Technologies & Distribution Ltd | Information & communication | 2026 |
| OX Trading LP | | 2013 |
| Oxalys International LP | | 2016 |
| Oxbrand Resources L.P. | | 2014 |
| Oxen Wealth LP | | 2015 |
| Oxengroup LP | | 2015 |
| Oxenwood Investments LP | | 2013 |
| Oxexy Ltd | Wholesale & retail | 2026 |
| Oxford Investment SP | | 2006 |
| Oxford Supreme LP | | 2017 |
| Oxford Technology Support L.P. | | 2012 |
| Oxfordco Ventures LP | | 2014 |
| Oxfordshire Colorectal Surgery Ltd. | Health & social care | 2009 |
| Oxgangs After School Club | Health & social care | 2003 |
| Oxgangs Care | Health & social care | 2001 |
| Oxgangs Investment Company Limited | Households | 2023 |
| Oxgangs LP | | 2016 |
| Oxgangs Premier Store Ltd | Wholesale & retail | 2022 |
| Oxgangs Superstore Ltd | Wholesale & retail | 2023 |
| Oxgate Nominees Limited | Professional & scientific | 1997 |
| Oxid Investment Ltd | Financial services | 2020 |
| Oxidant Corporation LP | | 2015 |
| Oxiflex Impex LP | | 2016 |
| Oxigen Inc Ltd | Wholesale & retail | 2019 |
| Oximarin Investment LP | | 2020 |
| Oximarin Ventures LP | | 2019 |
| Oxley Trading LP | | 2015 |
| Oxline Energy L.P. | | 2012 |
| Oxnp Solutions LP | | 2014 |
| Oxomo Fitness Limited | Wholesale & retail | 2021 |
| Oxtail Limited | Construction | 2024 |
| Oxton Smart LP | | 2016 |
| Oxton Solutions LP | | 2014 |
| Oxvale Impex L.P. | | 2014 |
| Oxwood Projects L.P. | | 2013 |
| OXX I (Scotland) Limited | Financial services | 2017 |
| OXX I GP LP | | 2017 |
| OXX II (Scotland) Limited | Financial services | 2020 |
| OXX II GP LP | | 2020 |
| OXX III FP LP | | 2026 |
| OXX LI General Partner LP | | 2016 |
| OXY Photography & Design Ltd | Professional & scientific | 2025 |
| Oxygen Projects L.P. | | 2016 |
| Oymak Property Investment Limited | Real estate | 2018 |
| OZ Edinburgh Ltd | Professional & scientific | 2020 |
| Ozay Limited | Financial services | 2016 |
| Ozazalina Limited | Wholesale & retail | 2025 |
| Ozgul Hair & Beauty Ltd | Other services | 2023 |
| Ozmavity Holding LP | | 2024 |
| Ozzy&Dart Ltd | Wholesale & retail | 2021 |
| O’Donnell (Holdings) Group Limited | Financial services | 2022 |
| O’Hanlon-Potter Enterprise Limited | Professional & scientific | 2025 |
| P & D Brewerton Limited | Households | 2019 |
| P & D Thomson & Co | Administrative & support | 2022 |
| P & I Taxis Limited | Other services | 2000 |
| P & J Anderson LLP | | 2013 |
| P & J Taxis Ltd. | Extraterritorial | 2006 |
| P & M Electrical Services Ltd | Construction | 2014 |
| P & P Investment Management Ltd | Extraterritorial | 2012 |
| P & S Caravan Park Ltd | Hospitality | 2026 |
| P & S Property Developments Limited | Construction | 2004 |
| P & V United Ltd | Hospitality | 2008 |
| P & W Capital Development | | 1994 |
| P and a Cabs Limited | Extraterritorial | 2008 |
| P and L Consultancy Ltd | Professional & scientific | 2026 |
| P and P Property Maintenance Ltd | Construction | 2026 |
| P C Hanover Ltd | Real estate | 2021 |
| P C T Partnership Limited | Education | 2002 |
| P Falconer Consulting Ltd | Professional & scientific | 2019 |
| P I Professions Ltd | Financial services | 2018 |
| P J Leggate & Co Limited | Real estate | 2007 |
| P Monteith Pipework Services Limited | Construction | 2015 |
| P R Lindsay Limited | Professional & scientific | 2017 |
| P W & Partners Ltd | Professional & scientific | 2019 |
| P&C Locum Limited | Professional & scientific | 2025 |
| P&J Facilities Ltd | Other services | 2024 |
| P&J Yang Limited | Hospitality | 2016 |
| P&O Scottish Ferries Ship Management Ltd. | Transport & logistics | 1919 |
| P. B. Partners + Co | | 1992 |
| P. Blackhall Ltd. | Construction | 1994 |
| P.D.E. Services Limited | Other services | 2008 |
| P.E. Binns Limited | Professional & scientific | 2004 |
| P.I.B Services Ltd | Construction | 2018 |
| P.M. Ranaldi (Fish Merchants) Limited | Wholesale & retail | 1966 |
| P.R.O.P.- Stress Centre | Health & social care | 1991 |
| P.T. Roberts & SON Limited | Wholesale & retail | 1941 |
| P.T.T. 5 Limited | Professional & scientific | 1995 |
| P.T.T. Title (Number 4) Limited | Professional & scientific | 1995 |
| P1 Contractors Limited | Construction | 2011 |