| Atom Property Developments Limited | Construction | 2023 |
| Atomos Global UK Limited | Extraterritorial | 2022 |
| Attain Health Management Services Ltd | Health & social care | 2010 |
| Attollos Technology Limited | Information & communication | 2011 |
| Aubray Construction Limited | Construction | 2010 |
| Audentia Holdings Ltd | Real estate | 2018 |
| Audentia One Ltd | Real estate | 2020 |
| Audio One Post Production Ltd | Information & communication | 2022 |
| Aura Bathrooms Limited | Wholesale & retail | 2023 |
| Auralas Limited | Information & communication | 2010 |
| Auravelle Group Limited | Manufacturing | 2026 |
| Aurora Construction and Security Limited | Information & communication | 2018 |
| Aurum Bar Limited | Hospitality | 2025 |
| Autocanteen Ltd | Information & communication | 2020 |
| Autohaus Investment Limited | Real estate | 2018 |
| Autologic Solutions Limited | Wholesale & retail | 2019 |
| AUTOM8TEST Ltd | Information & communication | 2025 |
| Autostem Limited | Administrative & support | 2019 |
| AV Jewellery Limited | Wholesale & retail | 2025 |
| Avant Gard Jewellery Limited | Wholesale & retail | 2017 |
| Avantgarde Motors Limited | Wholesale & retail | 1999 |
| Avatar Consulting Ltd | Professional & scientific | 2007 |
| Aveer Holding Limited | Real estate | 2023 |
| Avenue Pharmacy Limited | Wholesale & retail | 1986 |
| Avenue Therapies Ltd | Health & social care | 2017 |
| Avenue Wealth Management Limited | Financial services | 2020 |
| Avery & ALI Properties LLP | | 2019 |
| Avery & ALI Property Management Limited | Real estate | 2022 |
| Avery and ALI Law Ltd | Professional & scientific | 2023 |
| Avia Property Limited | Real estate | 2022 |
| Aviation Partners Ltd | Wholesale & retail | 2012 |
| Avid Technology Europe Limited | Wholesale & retail | 1991 |
| Aviram Ltd | Real estate | 2014 |
| Avisen UK Limited | Administrative & support | 2003 |
| Avisha Finance Ltd | Professional & scientific | 2007 |
| Avro Systems Technology Limited | Information & communication | 1985 |
| Awta Lottoracing Community Interest Company | Arts & recreation | 2015 |
| Axefix Limited | Manufacturing | 2022 |
| Axion Autos Ltd | Wholesale & retail | 2026 |
| Axis Build Limited | Construction | 2009 |
| Axis Electrical Contractors Limited | Construction | 2019 |
| Axis Freight Ltd | Transport & logistics | 2025 |
| Axton Consulting Limited | Other services | 2012 |
| Aylesbury Martial Arts School Limited | Arts & recreation | 2014 |
| Ayro Property Investments Limited | Real estate | 2022 |
| Ayurwell Ltd | Wholesale & retail | 2020 |
| Ayushaan Investments Limited | Real estate | 2017 |
| Aztec (UFH) Limited | Construction | 2024 |
| Aztec Flooring (Contracts) Ltd | Construction | 2023 |
| Aztecs Holdings Ltd | Financial services | 2025 |
| B G Digital Limited | Professional & scientific | 2008 |
| B K Kudhal Limited | Information & communication | 2012 |
| B P Collins LLP | | 2010 |
| B P Collins Services Limited | Professional & scientific | 1995 |
| B P Collins Trust Corporation Limited | Professional & scientific | 2008 |
| B R Systems Limited | Wholesale & retail | 2014 |
| B S RAI Enterprises Limited | Real estate | 2020 |
| B&B Paving and Landscaping Ltd | Administrative & support | 2025 |
| B&B Roofing and Building Ltd | Construction | 2024 |
| B.Morley Hair and Beauty Ltd | Other services | 2025 |
| B.Penhale Limited | Hospitality | 2026 |
| B2 Waterfront Ltd | Real estate | 2024 |
| B2G Ltd | Professional & scientific | 2019 |
| B3 Partners Limited | Professional & scientific | 2019 |
| Baba Food Stores Limited | Wholesale & retail | 2024 |
| BABIES1ST C.I.C. | Education | 2019 |
| Baby's Food Ltd | Manufacturing | 2025 |
| Badops Ltd | Professional & scientific | 2024 |
| Bahia VFX Limited | Information & communication | 2019 |
| Banc Corporation Limited | Real estate | 2004 |
| Banc Properties Limited | Real estate | 2004 |
| Banh MI & PHO Limited | Hospitality | 2014 |
| Banquva Ltd | Financial services | 2017 |
| Bar Boys Ltd | Hospitality | 2024 |
| Barhana Limited | Real estate | 2012 |
| Barlby Homes Ltd | Construction | 2018 |
| Barlby Ltd | Financial services | 2018 |
| Barlby Property Ltd | Real estate | 2018 |
| Barnard Cook London Ltd | Real estate | 2015 |
| Barrio 4 Ltd | Professional & scientific | 2016 |
| Basil JOE Engineering Limited | Construction | 2010 |
| Batik London Ltd | Wholesale & retail | 2026 |
| Baylore Ltd | Financial services | 2009 |
| BBP Pizza Limited | Hospitality | 2016 |
| BBW Management Limited | Real estate | 2014 |
| BCL Sheeprake Ltd | Construction | 2021 |
| Bcpaedsneo Private Limited | Health & social care | 2016 |
| BCS Agencies Limited | Wholesale & retail | 2017 |
| BCS Corporate Services Limited | Wholesale & retail | 2024 |
| BE Kind Ltd | Professional & scientific | 2017 |
| BE Your Best Educational Psychology Services Limited | Education | 2023 |
| Beachmount Arch Limited | Real estate | 2023 |
| Beachmount City Limited | Real estate | 2023 |
| Beachmount Group Limited | Financial services | 2023 |
| Beachmount OPS1 Limited | Hospitality | 2023 |
| Beachmount Soho Limited | Real estate | 2023 |
| Bear Enterprise Advisory Reinvestment Ltd | Professional & scientific | 2021 |
| Beau Bespoke (Construction) Limited | Construction | 2022 |
| Beau Bespoke (Maintenance) Limited | Construction | 2022 |
| Beau Bespoke (Special Projects) Limited | Construction | 2022 |