| AM Build Properties Ltd | Real estate | 2025 |
| AM Graphic Design Ltd | Arts & recreation | 2011 |
| Amaltas Property Investment Ltd | Real estate | 2020 |
| Aman Hospitality Ltd | Hospitality | 2023 |
| Aman Medical Services Ltd. | Health & social care | 2011 |
| Amathist Developments Limited | Real estate | 2006 |
| Amazing Grace Healthcare Limited | Health & social care | 2012 |
| Amber Optix Limited | Professional & scientific | 2003 |
| Amicos Ltd | Hospitality | 2026 |
| Amit & Tina Mohindra Limited | Real estate | 2017 |
| AMO Holdco Limited | Financial services | 2024 |
| Amory Clothing Limited | Wholesale & retail | 2025 |
| Ampersandesign Ltd | Professional & scientific | 2023 |
| Amria Consulting Limited | Administrative & support | 2024 |
| Anatolian Olive OIL Company Ltd | Wholesale & retail | 2017 |
| Andy Nails Limited | Other services | 2017 |
| Andy Pike's Asset Protection Ltd. | Administrative & support | 2007 |
| Annette Morton Sonography Ltd | Health & social care | 2025 |
| Apaya (Merchants) Limited | Information & communication | 2020 |
| Aphis Limited | Administrative & support | 2012 |
| Aplin Accountancy Ltd | Professional & scientific | 2016 |
| Apservices Electrical Ltd | Construction | 2024 |
| Apsley Court (Oxford) Freehold Limited | Households | 2010 |
| Apsley Court (Oxford) Management Company Limited | Households | 1987 |
| APV Boiler Services Ltd | Construction | 2009 |
| Aqua Tales Limited | Information & communication | 1997 |
| ARC Developments International (UK) Ltd | Professional & scientific | 2013 |
| Archway Bess SPV Limited | Energy | 2023 |
| Arcstrike Ltd | Public administration | 2025 |
| Arcturis Data (UK) Limited | Professional & scientific | 2018 |
| Arcturis Data Holdings Limited | Professional & scientific | 2015 |
| Arcturis Data Limited | Professional & scientific | 2018 |
| Area Property Holdings Limited | Real estate | 2013 |
| Arnold Developments Limited | Real estate | 1961 |
| Arnolds Way Residents Company Limited | Households | 2019 |
| Arraiz Dynamics Ltd | Professional & scientific | 2025 |
| Artemis Real Estate Ltd | Real estate | 2024 |
| Artisan Screen Limited | Manufacturing | 2005 |
| Ascend Africa | Education | 2014 |
| Asgon Ltd | Wholesale & retail | 2026 |
| Ashiana Property Management Ltd | Real estate | 2018 |
| Ashley House (Rectory Road) Management Company Limited | Households | 1995 |
| Ashmore Park Limited | Construction | 2015 |
| Asix Limited | Households | 1989 |
| Askie Kids AI Limited | Information & communication | 2026 |
| Associated Ltd | Information & communication | 2024 |
| Astravera Holdings Ltd | Real estate | 2025 |
| Atom Softworks Ltd | Information & communication | 2016 |
| Audire Care & Support Ltd | Health & social care | 2023 |
| Auto East Africa Freighters Limited | Wholesale & retail | 2010 |
| Avalanche R and B Ltd | Wholesale & retail | 2024 |
| Avery Court (Oxford) Management Company Limited | Households | 1997 |
| Aviaâ Ltd | Transport & logistics | 2016 |
| Avva Life Ltd | Wholesale & retail | 2025 |
| Axion Biosystems Manufacturing UK Ltd | Manufacturing | 2021 |
| Axium Holdings Limited | Financial services | 2022 |
| Aztec Property Ltd | Households | 2020 |
| B H Blackmore Holdings Limited | Financial services | 2021 |
| B H Blackmore Limited | Professional & scientific | 2002 |
| B Q Security Ltd | Administrative & support | 2026 |
| Back & Beyond Limited | Health & social care | 2006 |
| Back on Trend Ltd | Wholesale & retail | 2021 |
| Badgers Close (Forest Hill) Management Company Limited | Households | 2008 |
| Baikal AR Ltd | Information & communication | 2019 |
| Bainton Capital Partners Ltd | Professional & scientific | 2009 |
| Baldwin Domestic Appliances Limited | Manufacturing | 2014 |
| Balliol Properties Ltd | Real estate | 2025 |
| Bang on Ductwork Specialists Ltd | Construction | 2024 |
| Bankside Bites Ltd | Hospitality | 2025 |
| Bardia Property Management Ltd | Real estate | 2023 |
| Barnet Barber Oxon Ltd | Other services | 2025 |
| Barnewood Limited | Other services | 2009 |
| Barney’S Scaffolding Ltd | Construction | 2022 |
| Bartlett Judge Associates Ltd | Professional & scientific | 2019 |
| Basil Wyatt Holdings Limited | Construction | 1990 |
| Basil Wyatt Property Limited | Real estate | 2011 |
| Baskerville Business Consultancy Ltd | Administrative & support | 2017 |
| Bateman Painting and Decorating Limited | Construction | 2004 |
| Bathroomcraft Limited | Construction | 2018 |
| Bauts Services Limited | Real estate | 2019 |
| Baylis & Co Ltd | Wholesale & retail | 2001 |
| BBK Barbers Ltd | Other services | 2020 |
| BDH Projects Limited | Construction | 2003 |
| Beach Bunk Limited | Wholesale & retail | 2025 |
| Beauly Estates Ltd | Professional & scientific | 2020 |
| Beauly PM Ltd | Construction | 2021 |
| Beaumont Green (Sutton) Management Company Limited | Real estate | 2015 |
| Beckett House Management Company Limited | Real estate | 1988 |
| Beckwood Developments (Oxford) Limited | Construction | 2016 |
| Beckwood Garden Rooms Ltd | Construction | 2025 |
| Beckwood Holdings Ltd | Real estate | 2026 |
| Beechwood Solicitors Limited | Professional & scientific | 2008 |
| Begbroke Manor Management Company Limited | Households | 2006 |
| Belcarra Group Limited | Financial services | 2023 |
| Bellbeck Holdings Ltd | Real estate | 2026 |
| Belmark and Nightingale Limited | Construction | 2018 |
| Belmark Homes Limited | Construction | 2006 |
| Belmark Properties Limited | Real estate | 2015 |
| Belton Landscapes Ltd | Administrative & support | 2021 |
| Benedict's Consultant Surveyors Limited | Real estate | 1997 |