| APT Group Services Limited | Financial services | 2020 |
| Aqualis Limited | Construction | 2002 |
| Arbuc Limited | Real estate | 1981 |
| ARK New Homes Cornovii Limited | Construction | 2021 |
| ARK New Homes Limited | Construction | 2020 |
| ARK Prime Homes Limited | Construction | 2020 |
| Arrow Care Services Limited | Public administration | 2017 |
| Art Club @ the Studio Ltd | Education | 2025 |
| Art Omnivores Ltd. | Information & communication | 2013 |
| Artemis Industries Ltd | Professional & scientific | 2024 |
| Artichoke Management UK Limited | Households | 2014 |
| Asap Personal Couriers Limited | Transport & logistics | 2008 |
| ASB Assets Limited | Financial services | 2018 |
| Asbeau LP | | 2015 |
| Ashley Wallbridge Music Limited | Arts & recreation | 2013 |
| Ashspokemarket Ltd | Wholesale & retail | 2026 |
| Ashton Turner Fitness Limited | Other services | 2014 |
| Aster Academies Trust | Extraterritorial | 2014 |
| Aster Education | Extraterritorial | 2014 |
| Aster Homes Limited | Construction | 2007 |
| Aster LD Limited | Construction | 2019 |
| Aster Options Plus Limited | Professional & scientific | 2013 |
| Aster Property Limited | Construction | 2003 |
| Aster Solar Limited | Energy | 2015 |
| Aster Treasury PLC | Professional & scientific | 2013 |
| Aston Davies Limited | Professional & scientific | 2015 |
| Aston Events and Entertainment Limited | Arts & recreation | 2023 |
| Astoria Europe Limited | Wholesale & retail | 2025 |
| ATD Building and Plumbing Ltd | Construction | 2026 |
| Atticus LEX Ltd | Information & communication | 2024 |
| Atumbo Limited | Health & social care | 2022 |
| Audace Consulting Limited | Public administration | 2023 |
| AUK Holding Limited | Professional & scientific | 2008 |
| Aura Studios Limited | Real estate | 2000 |
| Auto Asad Limited | Wholesale & retail | 2022 |
| Auto Diagnostics and Servicing Limited | Manufacturing | 2008 |
| Autoleaf Limited | Wholesale & retail | 2025 |
| Avenir Energy Ltd | Other services | 2015 |
| Avery & Bennett Limited | Construction | 2003 |
| Avon Kitchen Limited | Hospitality | 2022 |
| Avon Trophies Limited | Wholesale & retail | 2004 |
| Avoncourt Property Investments Limited | Real estate | 1998 |
| Awdry Law LLP | | 2020 |
| Axom Limited | Arts & recreation | 1997 |
| AYS Consultancy Ltd | Professional & scientific | 2023 |
| B Butcher Ltd | Construction | 2025 |
| B.M Media Group Ltd | Information & communication | 2025 |
| B1 Padel Ltd | Professional & scientific | 2025 |
| B2M2 Limited | Information & communication | 2014 |
| Bailey and Sorley Electrical Limited | Construction | 2010 |
| Baked Tiles Limited | Wholesale & retail | 2017 |
| Balance Accounting Services Ltd | Professional & scientific | 2019 |
| Balston Agius Ltd | Administrative & support | 2010 |
| Bamber's External JET Washing Ltd | Administrative & support | 2024 |
| Bar Potterne Limited | Hospitality | 2025 |
| Barefoot Signs Limited | Professional & scientific | 2010 |
| Barley Hill Groundworks Ltd | Construction | 2024 |
| Barnet's Limited | Wholesale & retail | 2003 |
| Barratt and Sons Ltd | Real estate | 2024 |
| Bath and West Aviation LLP | | 2022 |
| Bath Road Building Company Limited | Construction | 2019 |
| BBA Solutions Limited | Administrative & support | 2013 |
| Bbhbear Limited | Professional & scientific | 2022 |
| BE Different Films Ltd | Information & communication | 2013 |
| Beans and Bits Ltd | Hospitality | 2025 |
| Beauty by ABI Ltd | Other services | 2022 |
| Beech Partnership Limited | Professional & scientific | 2009 |
| Beeswax Ltd | Wholesale & retail | 2015 |
| Belle VUE Farm Shire Limited | Hospitality | 2021 |
| Belvedere Associates Ltd | Professional & scientific | 2015 |
| Bengeho Limited | Administrative & support | 2019 |
| Benham Bodyworks Limited | Wholesale & retail | 2011 |
| Benham Mezzanine & Racking Ltd | Construction | 2024 |
| Berean Examiners Limited | Professional & scientific | 2014 |
| Best Travel Mugs Limited | Other services | 2020 |
| Beth Cuttell Antiques Ltd | Wholesale & retail | 2019 |
| Better Frames UK Limited | Professional & scientific | 2013 |
| Beyond Dementia | Health & social care | 1995 |
| Beyond the Wire Community Interest Company | Other services | 2024 |
| Bigglestone Limited | Construction | 2016 |
| Bigglestone Two Limited | Construction | 2025 |
| Bike HQ Limited | Wholesale & retail | 2016 |
| Bikeco Ltd | Wholesale & retail | 2014 |
| Bikes 'N' Boards Limited | Wholesale & retail | 2010 |
| BIN Game Ltd | Arts & recreation | 2026 |
| BIO Cleaning Solutions Ltd | Wholesale & retail | 2019 |
| BIO Plots Ltd | Professional & scientific | 2023 |
| Bioagrimed (Consultancy) Limited | Agriculture & fishing | 2012 |
| Biteback Products Ltd | Manufacturing | 2017 |
| Black Dog Coffee Co Ltd | Hospitality | 2022 |
| Black Rock Merchandising Limited | Wholesale & retail | 2014 |
| BLF Properties Limited | Real estate | 2021 |
| BLK LAB Developments Ltd | Real estate | 2023 |
| BLM Expert Consultancy Limited | Professional & scientific | 2018 |
| Block 317 (Poundbury) Management Company Limited | Real estate | 2018 |
| Blossom Nannies Limited | Other services | 2017 |
| Blucar Solutions Limited | Information & communication | 2013 |
| Blue Cloud Ventures Limited | Information & communication | 2023 |
| Blue Valley Software Ltd | Information & communication | 2001 |
| BM Safeguarding Limited | Professional & scientific | 2025 |