| 1664 Training Solutions Limited | Professional & scientific | 2024 |
| 18 Dinsmore Road Limited | Professional & scientific | 2003 |
| 1932 Oxford Ltd | Wholesale & retail | 2022 |
| 22 Labs Ltd | Professional & scientific | 2025 |
| 31-36 ST. Olaf's Road Limited | Households | 2008 |
| 64DEGREES(HEATING) Ltd | Construction | 2016 |
| 8 OCK Street Limited | Construction | 2024 |
| 93 Sirdar Road Management Company Limited | Households | 1997 |
| A. B. S. Plant Hire Limited | Administrative & support | 2005 |
| A.H. Willis and Sons Developments Limited | Construction | 2015 |
| A.H. Willis and Sons Holdings Limited | Financial services | 2015 |
| A.H. Willis and Sons Limited | Construction | 2002 |
| A.H. Willis and Sons Property Limited | Construction | 2015 |
| A.R. Cover Limited | Construction | 2003 |
| A.R.Geo Holdings Limited | Financial services | 2024 |
| AB Roofing Maintenance Ltd | Construction | 2025 |
| Abdul Catering Ltd | Hospitality | 2025 |
| Abingdon Events Partnership Ltd | Arts & recreation | 2021 |
| AC Precision Engineering Limited | Manufacturing | 2003 |
| ACCELER8 Commercial Ltd | Professional & scientific | 2023 |
| Acorn Finance and Business Services Limited | Financial services | 2022 |
| Acoustic Insights and Resilience Ltd | Professional & scientific | 2024 |
| ACT Sports Limited | Extraterritorial | 2018 |
| Active World Solutions C.I.C. | Water & waste | 2019 |
| Adelante Change Consulting Ltd | Professional & scientific | 2023 |
| Adventure Parc Limited | Hospitality | 2025 |
| AEB Engineering Ltd | Professional & scientific | 2019 |
| Aesthetics by A.M Limited | Other services | 2020 |
| Afrodist Ltd | Hospitality | 2024 |
| AG Hera Associates Ltd | Agriculture & fishing | 2026 |
| Agile Freedom Consulting Ltd | Information & communication | 2024 |
| Ahhj Consulting Limited | Information & communication | 2016 |
| Aimhigher Tutoring Services Ltd | Education | 2020 |
| AK Energy & Construction Ltd | Construction | 2015 |
| Alachey Trading Ltd | Wholesale & retail | 2026 |
| Alavander Ltd | Information & communication | 2021 |
| Alchemy Estates (Cadogan) Ltd | Real estate | 2024 |
| Alchemy Estates (Holywell) Ltd | Real estate | 2020 |
| Alchemy Estates Limited | Real estate | 1995 |
| Aldji Holding Limited | Financial services | 2025 |
| Alexander George Fine Antiques Limited | Wholesale & retail | 2016 |
| Alistair Kitchener Personal Training Ltd | Arts & recreation | 2008 |
| Alphageo Ltd | Professional & scientific | 2020 |
| Alser (UK) Limited | Manufacturing | 1988 |
| Aluminium Manufacturing Ltd | Manufacturing | 2010 |
| Amey Investing Company Ltd | Financial services | 2021 |
| Amicus Recruitment Group Limited | Administrative & support | 2017 |
| AMK Financial Services Ltd | Professional & scientific | 2021 |
| AMPLEXUS-P3M Ltd | Professional & scientific | 2012 |
| AMR Sheet Metal Fabrication Limited | Manufacturing | 2003 |
| Andrew Goodwin & Associates Limited | Professional & scientific | 2009 |
| Andrew Townsend Architects Limited Liability Partnership | | 2023 |
| Andy Lole SIP Ltd | Education | 2023 |
| Angelic Angels Limited | Other services | 2007 |
| Annfar Limited | Health & social care | 2018 |
| Anopaishe Ltd | Health & social care | 2014 |
| Antama Limited | Real estate | 2021 |
| Apex & Co Construct Ltd | Construction | 2024 |
| APEX4 Trading Limited | Financial services | 2023 |
| Apogee Consultancy Group Ltd | Professional & scientific | 2026 |
| Arazma Limited | Information & communication | 2022 |
| Archangel Construction Limited | Construction | 2020 |
| Archer Properties Limited | Households | 1935 |
| Archgreen Properties Ltd | Households | 1999 |
| Ardington Archives LLP | | 2012 |
| Arron Twamley Planning (ATP) Ltd | Professional & scientific | 2019 |
| Ashcroft Art Limited | Wholesale & retail | 2012 |
| Ashcroft Consultancy Limited | Professional & scientific | 2012 |
| Aspect Woodworking Limited | Manufacturing | 2005 |
| Aspirata Limited | Professional & scientific | 2005 |
| Asset Accounting (Swindon) Ltd | Professional & scientific | 2020 |
| AST Construction Ltd | Construction | 2015 |
| AT Art Limited | Wholesale & retail | 2021 |
| AT Keelys Faringdon Limited | Other services | 2019 |
| Atlanta Biological Europe Ltd | Professional & scientific | 2013 |
| Austin Autosport Ltd | Arts & recreation | 2024 |
| Aviation Cardiology Services Ltd | Health & social care | 2023 |
| Aviation Optical and Medical Limited | Health & social care | 2006 |
| B2L Property Ltd | Real estate | 2016 |
| Ballgame Limited | Real estate | 2002 |
| Bambino Limited | Education | 2005 |
| Barcote Park Management Limited | Administrative & support | 1996 |
| Barlow Geosafety Ltd | Professional & scientific | 2018 |
| Barnox Ltd | Financial services | 2015 |
| Barrett’S Engineering Ltd | Professional & scientific | 2025 |
| Barton Animalcare Services Limited | Professional & scientific | 2002 |
| Basilica Wealth Advisory Ltd | Financial services | 2026 |
| Bastion House Developments Limited | Real estate | 1989 |
| Baugh Fell Holdings Ltd | Financial services | 2024 |
| BDH Flooring Ltd | Construction | 2026 |
| Beakstons Ltd | Real estate | 2021 |
| Beeway Global Solutions Ltd | Wholesale & retail | 2025 |
| Bellbrae Investments Limited | Real estate | 1973 |
| Berners-Allsopp Estate Management Co. Limited | Real estate | 1975 |
| Best Food 2000 Ltd | Hospitality | 2021 |
| BGG Garden & Tree Care Limited | Administrative & support | 2010 |
| BGG Properties Faringdon Limited | Real estate | 2024 |
| BIB Limited | Extraterritorial | 1957 |
| Big PAW Dog Care Ltd | Other services | 2013 |
| Big PAW Software Ltd | Information & communication | 2010 |