| Autobody Aldermaston Ltd | Wholesale & retail | 2019 |
| Autocraft (Kingsclere) Ltd | Wholesale & retail | 2010 |
| Autohaus (Berkshire) Limited | Wholesale & retail | 2018 |
| Autologic Automation Limited | Information & communication | 1996 |
| Automate App Limited | Transport & logistics | 2019 |
| Automerc Newbury Limited | Wholesale & retail | 2018 |
| Automotive Consulting Limited | Professional & scientific | 2025 |
| Autory Ltd | Manufacturing | 2025 |
| Autoslide Ltd | Financial services | 1989 |
| Autosolutions Newbury Ltd | Wholesale & retail | 2023 |
| AUTOVALET2U Limited | Other services | 2017 |
| AVA Bella Ltd | Professional & scientific | 2014 |
| Avacyn IT Ltd | Information & communication | 2013 |
| Avalon Retail Ltd | Wholesale & retail | 2025 |
| AVB Advisory Limited | Professional & scientific | 2022 |
| AVE Cabs Newbury Limited | Extraterritorial | 2026 |
| Avery Estate Maintenance Ltd | Construction | 2016 |
| AVO Music Limited | Arts & recreation | 2017 |
| AWG Electrical Services Limited | Construction | 2023 |
| AXE & SON Ltd | Administrative & support | 2025 |
| Axtell Windows Ltd | Construction | 2023 |
| Ayfjow Ltd | Financial services | 2019 |
| Aymy Limited | Administrative & support | 2012 |
| Ayrass Ltd | Wholesale & retail | 2025 |
| Ayurveda Anytime Ltd | Health & social care | 2023 |
| Azhar Consulting UK Limited | Professional & scientific | 2025 |
| Azimuth Digital Services Ltd | Information & communication | 2025 |
| Aztec Services Swimming Pool Maintenance Limited | Other services | 2009 |
| Azulejo Holdings Ltd | Real estate | 2023 |
| B & B Developments (Berkshire) Ltd | Construction | 2015 |
| B & L Ruso Limited | Construction | 2007 |
| B Side Barbers Ltd | Other services | 2019 |
| B Side Records Ltd | Wholesale & retail | 2020 |
| B Vraj Limited | Real estate | 2024 |
| B&P Interactive Limited | Information & communication | 2000 |
| B.H. Company Secretaries Limited | Professional & scientific | 1992 |
| B.H. Company Services Limited | Professional & scientific | 1993 |
| B2 Cooling Ltd | Construction | 2026 |
| B2B Properties Limited | Construction | 2012 |
| B2B Relocations & HR Services Limited | Administrative & support | 2016 |
| B51 Ventures Ltd | Financial services | 2021 |
| Babbageworks Limited | Professional & scientific | 2021 |
| Bachs Property Ltd | Real estate | 2024 |
| Back on Form Ltd | Professional & scientific | 2014 |
| Baggerman Property Services Limited | Real estate | 2020 |
| Baggerman Wealth Management Ltd. | Financial services | 2014 |
| Bailey & Passmore Properties Limited | Construction | 2014 |
| Bailey and Passmore Lettings Limited | Real estate | 2015 |
| Baking Waves Ltd | Manufacturing | 2009 |
| Baldev's Dental Care Ltd | Health & social care | 2020 |
| Baldings Farming Limited | Agriculture & fishing | 1997 |
| Ball Hill Garage Limited | Wholesale & retail | 2019 |
| Balley's Forecourt Services Ltd | Wholesale & retail | 2017 |
| Balvaird Consulting Services Ltd | Professional & scientific | 2011 |
| BAM Technical Ltd | Professional & scientific | 2024 |
| BAN Hass Ltd | Health & social care | 2024 |
| Banana London Limited | Wholesale & retail | 2009 |
| Banbury Marques Limited | Other services | 2007 |
| Band Baaje Film UK Ltd. | Information & communication | 2018 |
| Banfield Real Estate Solutions Ltd | Professional & scientific | 2010 |
| Banjo Cycles Limited | Wholesale & retail | 2004 |
| Banks & Co Limited | Professional & scientific | 2010 |
| Banks & Klein Ltd. | Other services | 2016 |
| Bantec Limited | Information & communication | 1995 |
| Bapa Ltd | Wholesale & retail | 2015 |
| Barafundle Whenua Ltd | Construction | 2018 |
| Barcot Consulting Limited | Professional & scientific | 2021 |
| Bark N Bubbles Dog Grooming Ltd | Agriculture & fishing | 2024 |
| Barker Project Management Ltd | Professional & scientific | 2007 |
| Barking Tree Limited | Professional & scientific | 2009 |
| Barkis Partners Limited | Financial services | 2025 |
| Barley Technology Limited | Information & communication | 2024 |
| Barnard Contracts (UK) Limited | Administrative & support | 2011 |
| Barnato Care LLP | | 2025 |
| Barnes (Aldbourne) Limited | Professional & scientific | 1999 |
| Barnes Coaches Limited | Transport & logistics | 1982 |
| Barnfield Engineering Services Limited | Construction | 1999 |
| Barns Hotel Bedford Limited | Hospitality | 1990 |
| Barrett & Thomson Estates Limited | Real estate | 2008 |
| Barron Analytical Limited | Extraterritorial | 1994 |
| Barry Jackson Associates Limited | Construction | 2014 |
| Bartlett’S Childers Limited | Extraterritorial | 2022 |
| BASE32 Limited | Information & communication | 2022 |
| Basingstoke Eats Ltd | Hospitality | 2026 |
| Basingstoke Sports Club Limited | Arts & recreation | 2018 |
| Basset Down Balancing Ltd | Wholesale & retail | 2013 |
| Bastion Safety Ltd | Professional & scientific | 2025 |
| Bateswilcox Mortgage Solutions Ltd | Financial services | 2019 |
| Batsford Stud Ltd | Agriculture & fishing | 2011 |
| Baxzilla Consulting Limited | Information & communication | 2008 |
| Bayreuth Properties Limited | Real estate | 2004 |
| BB - Sustainable Tourism CIC | Other services | 2023 |
| BC Precision Installations Limited | Manufacturing | 2014 |
| BCL Numedia Limited | Wholesale & retail | 2003 |
| Bcomp 517 Limited | Other services | 2017 |
| Bcomp 520 Limited | Other services | 2017 |
| Bdmn Limited | Professional & scientific | 2017 |
| BDZ Investments Limited | Professional & scientific | 2016 |
| BE Insightful Limited | Professional & scientific | 2019 |
| BE YOU Project CIC | Health & social care | 2022 |