| Arete Business Solutions Limited | Professional & scientific | 2023 |
| Argute Limited | Professional & scientific | 2013 |
| Argyle Innovation Limited | Hospitality | 2024 |
| ARK Print Limited | Manufacturing | 2012 |
| ARK Recording Studios Limited | Information & communication | 2001 |
| Arkwright & Co SW Limited | Real estate | 2014 |
| Armstrong Webb Limited | Information & communication | 2007 |
| Arrestair Products Ltd. | Professional & scientific | 1998 |
| Art Cleaning Limited | Administrative & support | 2009 |
| Art Friend Gallery Limited | Wholesale & retail | 2026 |
| Art Joy Limited | Arts & recreation | 2022 |
| Arten Gill Limited | Professional & scientific | 2017 |
| Artificial Instinct Limited | Information & communication | 2018 |
| Artist Management Worldwide Ltd | Administrative & support | 2017 |
| Artists Proof Limited | Wholesale & retail | 2021 |
| AS Clark Biomass LLP | | 2021 |
| As&Ms Agency Limited | Wholesale & retail | 2004 |
| ASH Soni Limited | Professional & scientific | 2013 |
| Ashcroft Yard Limited | Households | 2025 |
| Ashdon Windmill Trust Limited | Education | 1999 |
| Ashley Christopher Limited | Financial services | 2004 |
| Ashwell London Investments Ltd | Real estate | 2018 |
| Ashwell London Real Estate Ltd | Real estate | 2017 |
| ASK Ladder Limited | Financial services | 2016 |
| Aspire & Co Limited | Health & social care | 2014 |
| Aspire (CRP) General Partner Limited | Real estate | 2017 |
| Aspire (CRP) Limited | Real estate | 2016 |
| Aspire Medical Aesthetics Ltd | Health & social care | 2012 |
| Aspired Studios Limited | Professional & scientific | 2026 |
| Aspraes Limited | Manufacturing | 2006 |
| Astor Holdings Limited | Financial services | 2023 |
| Asyn Portfolio Limited | Real estate | 2011 |
| Asyn Solutions Limited | Professional & scientific | 2018 |
| Atanga Associates Ltd | Professional & scientific | 2023 |
| Atelier Orme Ltd | Wholesale & retail | 2023 |
| Atellier Ltd | Information & communication | 2018 |
| Atlas Hyde Ltd | Other services | 2018 |
| Atlas Quant Ltd | Information & communication | 2025 |
| Atlas Storage Ltd | Transport & logistics | 2026 |
| Atomlynn Limited | Real estate | 1980 |
| Atricona Limited | Professional & scientific | 2014 |
| Attribute Marketing Ltd | Professional & scientific | 2015 |
| Attrium Consulting Ltd | Real estate | 2025 |
| Attrium Properties Ltd | Real estate | 2025 |
| Aubard Investments Limited | Construction | 2021 |
| Audley END Miniature Railway Ltd | Administrative & support | 2018 |
| Augmented Analytics Ltd | Information & communication | 2021 |
| Augmented Optics Ltd | Administrative & support | 2017 |
| AUM Invest Ltd | Mining & quarrying | 2025 |
| Auravisions Limited | Construction | 2005 |
| Auto Store Valet Ltd | Administrative & support | 2025 |
| Autojobs Limited | Administrative & support | 2003 |
| AVA Analytics Limited | Information & communication | 2019 |
| Avalen Services Ltd | Other services | 2024 |
| Avalon Aircraft Maintenance Services Ltd | Transport & logistics | 2025 |
| Aviation Ground Support (Norwich) Limited | Administrative & support | 2006 |
| Aviation Ground Support Holdings Limited | Financial services | 2020 |
| Aviation Ground Support Limited | Transport & logistics | 2004 |
| Avionic and Electrical Systems Limited | Transport & logistics | 2006 |
| AWM Properties Limited | Construction | 2006 |
| Axministr Limited | Hospitality | 2019 |
| AY Ltd | Extraterritorial | 2008 |
| B E M Ventures LLP | | 2025 |
| B Hurst & SON Limited | Construction | 2010 |
| B W Distribution Ltd | Extraterritorial | 2018 |
| B&L Joint Ventures Limited | Information & communication | 2023 |
| B.I.M Holdings Limited | Wholesale & retail | 2021 |
| B8 Zone Ltd | Wholesale & retail | 2026 |
| Bailey Hills Estates Ltd | Manufacturing | 2014 |
| Bampleton Properties Limited | Construction | 2020 |
| Barbershop Company Property Rentals Limited | Other services | 2000 |
| Bargoed PV Limited | Energy | 2013 |
| Barley Management Ltd | Households | 2020 |
| Barnards Court (Saffron Walden) Management Limited | Households | 1979 |
| Barnett Simmons LLP | | 2024 |
| Barnwell Electrical Company Limited | Construction | 1971 |
| Barry Voce Associates Ltd | Information & communication | 2018 |
| Barton Biostatistics Ltd | Professional & scientific | 2022 |
| Bartram Services Limited | Administrative & support | 2003 |
| Barzel Capital Group Ltd | Administrative & support | 2026 |
| Base RX Limited | Professional & scientific | 2025 |
| BCG (Colchester) Limited | Extraterritorial | 2015 |
| Bckrs Borrower Limited | Administrative & support | 2018 |
| Bckrs Holdco Limited | Financial services | 2018 |
| BCP Securities UK Ltd | Financial services | 2021 |
| Bdnp (Poppys Barn) Ltd | Hospitality | 2025 |
| Be&Ee Housing Co Limited | Administrative & support | 2024 |
| Beachwreck Ltd | Administrative & support | 2020 |
| Beachwreck Properties Ltd | Administrative & support | 2022 |
| Bearwalden Properties Limited | Real estate | 2025 |
| Bearwalden Property Holdings Limited | Financial services | 2025 |
| Bearwalden Topco Limited | Financial services | 2025 |
| Beauty by Post Ltd. | Wholesale & retail | 1996 |
| Bebody Wellness Ltd | Arts & recreation | 2024 |
| Becky Glover Limited | Professional & scientific | 2019 |
| BEE Investment Holdings Ltd | Real estate | 2024 |
| Beechglade Limited | Real estate | 1984 |
| Beetle Capital Partners LLP | | 2008 |
| Bell Day Nursery Community Interest Company | Education | 2010 |
| Bell One Limited | Wholesale & retail | 2024 |