| Archer Risk Management UK Ltd | Wholesale & retail | 2026 |
| Archkingtech Limited | Professional & scientific | 2006 |
| Archway Partnerships (Oxford) Ltd | Professional & scientific | 2020 |
| Ariane Systems UK Limited | Manufacturing | 2005 |
| Arilia Movement & Wellness Online Therapy Limited | Health & social care | 2026 |
| Arkitektus Consulting Ltd | Professional & scientific | 2026 |
| Arkwright Aviation Limited | Other services | 2022 |
| Art of Image Ltd. | Information & communication | 2002 |
| Art,Antiques & Autos Limited | Wholesale & retail | 2000 |
| Artelios Ltd | Hospitality | 2025 |
| Arthur Window Cleaning Ltd | Administrative & support | 2021 |
| Artstash Creative Services Ltd | Professional & scientific | 2024 |
| Artstash Limited | Information & communication | 2024 |
| Ashburton Limited | Manufacturing | 2004 |
| ASK4SUPPORT Limited | Information & communication | 2011 |
| Aspen Group Limited | Real estate | 2024 |
| Assegai Security Ltd | Administrative & support | 2003 |
| Assoc. of Heritage Engineers Limited | Other services | 2020 |
| Aston Martin Owners Club Limited | Other services | 1951 |
| Astut Ltd | Information & communication | 2025 |
| Atalanta Properties Limited | Real estate | 1964 |
| Atgr Ltd | Professional & scientific | 2006 |
| Atil Trading Limited | Wholesale & retail | 2017 |
| Attention First Ltd | Information & communication | 2026 |
| Auburn Ltd | Public administration | 2022 |
| Austin Morris IT Consulting Limited | Information & communication | 2019 |
| Automotive Data Systems Limited | Wholesale & retail | 2017 |
| AVA Wines Ltd | Wholesale & retail | 2023 |
| Avalon Kennels Ltd | Hospitality | 2014 |
| Avalon Pool Cover Services Limited | Other services | 2013 |
| AVR Property Maintenance Limited | Construction | 2014 |
| Awakening Flow Ltd | Professional & scientific | 2021 |
| AXE Capital Partners Ltd | Professional & scientific | 2025 |
| Azolla AI Limited | Information & communication | 2026 |
| Azure Advisory Limited | Professional & scientific | 2025 |
| B H Emporium Ltd | Wholesale & retail | 2022 |
| B&R Huckvale Ltd | Information & communication | 2022 |
| B-Z Building Services Ltd | Construction | 2023 |
| B. North & Sons (West Wycombe) Limited | Real estate | 1946 |
| Babble (U.K.) Limited | Extraterritorial | 1996 |
| Bach Education and Research Limited | Professional & scientific | 1983 |
| Bachelor Construction Ltd | Construction | 2023 |
| Back Roads Production Limited | Information & communication | 2016 |
| Backcountry Audio Ltd | Information & communication | 2026 |
| Baguio Care Solutions Limited | Information & communication | 2017 |
| Ballooner Limited | Wholesale & retail | 2007 |
| Banana and Custard Limited | Wholesale & retail | 2010 |
| Bank View Property Finance Limited | Financial services | 2022 |
| Bankside Investments Limited | Professional & scientific | 1964 |
| Bantam Technologies Limited | Information & communication | 2015 |
| Bardells Services Limited | Other services | 2020 |
| Barleycorn Removals Limited | Transport & logistics | 2016 |
| Barrel Technologies Ltd | Hospitality | 2023 |
| Bart's Newbury Limited | Construction | 2020 |
| Bath and Shower House Limited | Extraterritorial | 2021 |
| Battle Wardrobe Ltd | Manufacturing | 2015 |
| BB & O Agricultural Services Limited | Agriculture & fishing | 2024 |
| Bcas Limited | Wholesale & retail | 1988 |
| BE Plumbing Ltd | Construction | 2021 |
| Beacroft (Farms) Limited | Agriculture & fishing | 1963 |
| Beasley Bookkeeping Ltd | Professional & scientific | 2013 |
| Beauty Within Cholsey Ltd | Other services | 2023 |
| Beechcroft Freeholds Tring NO 1 Limited | Construction | 2017 |
| Beechcroft Freeholds Tring NO 2 Limited | Construction | 2017 |
| Beechcroft Land Limited | Construction | 2012 |
| Beechcroft Trust Limited(The) | Administrative & support | 1985 |
| Beechlight Ltd | Professional & scientific | 2016 |
| Beewatch Ltd | Manufacturing | 2022 |
| Begolden Ltd | Wholesale & retail | 2009 |
| Behind Closed Doors Limited | Manufacturing | 1994 |
| Bench.Direct Ltd | Professional & scientific | 2020 |
| Benjamin & Partners Ltd | Financial services | 2024 |
| Benson Chop Ltd | Other services | 2025 |
| Benson Flooring Limited | Construction | 2020 |
| Benson Hydro Limited | Energy | 2011 |
| Benson Roofbox Hire Limited | Administrative & support | 2024 |
| Benson Sawmills Ltd | Wholesale & retail | 2013 |
| Benson Waterfront Ltd | Hospitality | 2025 |
| Berinsfield Amateur Boxing Club | Arts & recreation | 2003 |
| Berinsfield Health Care Services Limited | Wholesale & retail | 2007 |
| Berrick PUB Company Limited | Hospitality | 2025 |
| Bervisol Limited | Professional & scientific | 2010 |
| Better People Ltd | Administrative & support | 2009 |
| Betts Farm & Property Management Limited | Agriculture & fishing | 1978 |
| Big Brothers Big Sisters UK Foundation | Other services | 2019 |
| Big Potato Records Limited | Information & communication | 2007 |
| Big Wave Technologies Ltd | Information & communication | 2021 |
| Binarymonks Ltd | Information & communication | 2016 |
| Bioabundance Community Interest Company | Other services | 2020 |
| Birchbeck Managements Limited | Professional & scientific | 1993 |
| Bite ME Burger Ltd | Administrative & support | 2021 |
| Bite ME Cakes Ltd | Hospitality | 2024 |
| Bite ME Limited | Hospitality | 2023 |
| Bite the Beat Limited | Information & communication | 2025 |
| Bizitshop.Com Ltd | Information & communication | 2006 |
| Biznis Cards Limited | Manufacturing | 2002 |
| Blackened Window Ltd | Real estate | 2021 |
| Blackwater Studio (Oxford) Ltd | Professional & scientific | 2020 |
| Blenheim Landscape Services Ltd | Administrative & support | 2020 |
| Blewburton Limited | Professional & scientific | 2016 |