| AV Events (Reading) Limited | Information & communication | 2017 |
| Aventae Ltd | Professional & scientific | 2020 |
| Avento Property Maintenance Ltd | Construction | 2024 |
| Avia Boiler Care Limited | Administrative & support | 2002 |
| Avion Rise Limited | Construction | 2026 |
| Avonchem Diagnostics Limited | Other services | 2010 |
| AVR Developments Ltd | Real estate | 2018 |
| Awdio Ltd | Manufacturing | 2022 |
| AWP Solutions Ltd | Hospitality | 2023 |
| AWT Trim Centre Ltd | Manufacturing | 2010 |
| Awystudios Limited | Health & social care | 2025 |
| Axiom ARC Ltd | Real estate | 2025 |
| Aynhoe Park Interiors Limited | Wholesale & retail | 2006 |
| Aynhoe Park LLP | | 2019 |
| Ayres Accounting Limited | Professional & scientific | 2021 |
| AZ Spares Limited | Wholesale & retail | 2025 |
| Azura Limited | Construction | 1996 |
| B & E Transport (Witney) Limited | Administrative & support | 2003 |
| B S C C Investments Limited | Extraterritorial | 2015 |
| B&C Cotswold Properties Limited | Real estate | 2024 |
| B.Buckingham and Sons Limited | Agriculture & fishing | 1971 |
| B.J.S.(London)Limited | Professional & scientific | 1957 |
| Ba.Aba Software Limited | Information & communication | 2010 |
| Baculo Consulting Limited | Professional & scientific | 2008 |
| Badbury Fields Faringdon Limited | Households | 2024 |
| Baern Consulting Ltd | Professional & scientific | 2025 |
| BAH Building Limited | Construction | 2025 |
| BAH Commercials Ltd | Wholesale & retail | 2025 |
| Bahcb Ltd | Administrative & support | 2026 |
| Bahn Ltd | Administrative & support | 2021 |
| Bain Aviation Services Ltd | Education | 2023 |
| Baked Witney Ltd | Hospitality | 2023 |
| Bakers Butchers Limited | Wholesale & retail | 2003 |
| Balanced Physio Limited | Health & social care | 2018 |
| Balfour Business Centre Management Ltd | Real estate | 2014 |
| Bama House Productions Limited | Information & communication | 2019 |
| Bampton Design Limited | Manufacturing | 1988 |
| Bampton House Limited | Manufacturing | 2019 |
| Bampton Lanes Management Limited(The) | Households | 1986 |
| Bampton Satchwell Bull Limited | Real estate | 2019 |
| Banbury Fire and Security Services Ltd | Administrative & support | 2021 |
| Banbury Fire and Security Systems Ltd | Administrative & support | 2021 |
| Banbury Road Ltd | Construction | 2020 |
| Banbury Security Ltd | Financial services | 2021 |
| Bane Family Holdings Ltd | Financial services | 2026 |
| Bankingwise Limited | Professional & scientific | 2010 |
| Bar Gurus Events Services Limited | Extraterritorial | 2025 |
| Bar in the Box Limited | Hospitality | 2020 |
| Barcroft (Farnborough) Ltd | Construction | 2025 |
| Barcroft Estates Limited | Construction | 2021 |
| Bare Pubs Limited | Hospitality | 2022 |
| Baring Defence Limited | Manufacturing | 2026 |
| Baring Fine Art Ltd | Wholesale & retail | 2009 |
| Barley Conker Holdings Ltd | Financial services | 2024 |
| Barleycorn Ltd | Real estate | 2014 |
| Barnwell Investments Limited | Real estate | 1953 |
| Barrow Road Ltd | Construction | 2020 |
| Bartco Limited | Wholesale & retail | 2006 |
| Bartholomew Toogood Limited | Real estate | 2019 |
| Bartington Defence and Aerospace Limited | Financial services | 2024 |
| Bartington Holdings Limited | Financial services | 2020 |
| Bartington Instruments Limited | Manufacturing | 1985 |
| Bartlett Brothers(Witney)Limited | | 1958 |
| Base Rentals Ltd | Real estate | 2025 |
| BASE4 Marketing Limited | Professional & scientific | 2015 |
| Baseline Arts Limited | Information & communication | 1998 |
| Baseline Projects Limited | Other services | 1995 |
| Basset Down Complex Limited | Arts & recreation | 2021 |
| Bath Place Hotel Limited | Hospitality | 2011 |
| Bath Simple Storage Ltd | Transport & logistics | 2024 |
| Bathstone Shoot Locations Ltd | Arts & recreation | 2024 |
| Baughan Pest Control Limited | Administrative & support | 2016 |
| Bay Tree Joinery Ltd | Construction | 2013 |
| Baya Ltd | Real estate | 2022 |
| Baylin Associates Limited | Professional & scientific | 2018 |
| Bayswater Holdings Limited | Real estate | 2018 |
| Baytree Metal Roofing Ltd | Construction | 2022 |
| Bayworth Construction Limited | Construction | 2015 |
| Bazooka Services Limited | Professional & scientific | 2023 |
| Bbackborne Limited | Administrative & support | 2018 |
| BBC Masonry Ltd | Construction | 2014 |
| BBK - Life of Riley Ltd | Extraterritorial | 2019 |
| BBK on the Road 2023 Limited | Information & communication | 2022 |
| BBV Creative Limited | Professional & scientific | 2006 |
| BC Genomics Ltd | Professional & scientific | 2026 |
| BDR Building & Carpentry Services Limited | Construction | 2007 |
| BE Fire Smart Limited | Extraterritorial | 2012 |
| BE More Curious Limited | Professional & scientific | 2015 |
| Beadle Construction Limited | Construction | 2007 |
| Beament Leslie Thomas Recruitment Consultancy Limited | Administrative & support | 1987 |
| Beanbag Natural Health Limited | Wholesale & retail | 2002 |
| Beechgate Management Limited | Households | 1990 |
| Beechwood Avenue Limited | Construction | 2018 |
| Beechwood Avenue Properties Limited | Real estate | 2019 |
| Beechwood Division Limited | Other services | 2025 |
| Beechwood Kitchens Ltd | Extraterritorial | 2003 |
| Beedell Property Services Ltd | Real estate | 2026 |
| Behaviour Consulting Limited | Administrative & support | 2018 |
| Belbroughton Road Limited | Construction | 2025 |
| Bell Group Holdings Limited | Financial services | 2007 |