| ASH BOW Limited | Construction | 2024 |
| Ashavan Services Limited | Professional & scientific | 2010 |
| Ashdown Catering Services Ltd | Professional & scientific | 2026 |
| Ashley Bennett Mortgages Ltd | Financial services | 2021 |
| Ashley Community Care Services Limited | Health & social care | 2015 |
| Ashton Court (Laindon) Management Limited | Real estate | 2015 |
| Ashwood & Birch Bespoke Joinery Ltd | Hospitality | 2017 |
| Asia Benfleet Ltd | Hospitality | 2019 |
| ASK ME Consultancy Ltd | Transport & logistics | 2016 |
| Aslan Estates Limited | Real estate | 1998 |
| Aspect Air Ltd | Manufacturing | 2014 |
| Aspect Consult Limited | Professional & scientific | 2020 |
| Aspenair Environmental Ltd | Extraterritorial | 2012 |
| Aspinall's Windows and Doors Limited | Construction | 2018 |
| Aspinalls House Projects Limited | Construction | 2026 |
| Aspire Agency LLP | | 2010 |
| Aspros Consultancy Limited | Administrative & support | 2015 |
| Asset Contracts Limited | Construction | 2020 |
| Asset Formation Limited | Real estate | 2023 |
| Associated Security Systems Limited | Administrative & support | 2002 |
| Aster Facility Management Ltd. | Professional & scientific | 2009 |
| Asternovus Ltd | Information & communication | 2022 |
| Astley Drylining Ltd | Construction | 2026 |
| Aston Berkeley Ventures Limited | Real estate | 2018 |
| Astrascape Ltd | Extraterritorial | 2020 |
| Athena Flooring & Rugs Ltd | Construction | 2015 |
| Atish Enterprises Limited | Wholesale & retail | 2015 |
| ATKINSONEADE83 Limited | Real estate | 2020 |
| Atlas Consulting Group Ltd | Professional & scientific | 2025 |
| Atlas Demolition & Recycling Ltd | Administrative & support | 2013 |
| Atlas Trustees Ltd | Professional & scientific | 2012 |
| Atom Services Limited | Construction | 2019 |
| Auburn Counselling Services Ltd | Professional & scientific | 2019 |
| Audiofiesta Ltd | Administrative & support | 2025 |
| Auger Estates Limited | Real estate | 2025 |
| Augural Ltd | Other services | 2019 |
| Aurator Limited | Administrative & support | 2011 |
| Austin Construction Ltd | Construction | 2023 |
| Austin Property Investments Ltd | Real estate | 2015 |
| Autism ACT Limited | Education | 2022 |
| Auto Clinic Limited | Wholesale & retail | 2003 |
| Auto-Plas Ltd | Manufacturing | 2019 |
| Autoclad Limited | Administrative & support | 2006 |
| Autoinn Limited | Extraterritorial | 2023 |
| Automotive Servicing Ltd | Wholesale & retail | 2018 |
| AV Kingdom Limited | Construction | 2022 |
| Avario Concepts Ltd | Information & communication | 2026 |
| Avex Markets Limited | Extraterritorial | 2013 |
| Avgeekhangar Limited | Wholesale & retail | 2026 |
| Avondale Consult Limited | Other services | 2024 |
| AVW Tech PVT Ltd | Information & communication | 2024 |
| Awardhedge Limited | Households | 1995 |
| AWT Associates Ltd | Other services | 2020 |
| AX Power Components Limited | Professional & scientific | 2016 |
| Axis Scaffolding Ltd | Construction | 2023 |
| AYD Nutrition Ltd | Hospitality | 2025 |
| Aydot Ltd | Transport & logistics | 2018 |
| Ayling Associates Ltd | Professional & scientific | 2020 |
| Ayvik Services Limited | Administrative & support | 2002 |
| Azad Essex Barber Ltd | Other services | 2024 |
| Azazzo Ltd | Other services | 2022 |
| B & B Heating (London) Limited | Construction | 2021 |
| B & M Carpenters Ltd | Construction | 2012 |
| B a Taunton Ltd | Construction | 2011 |
| B B Art Ltd | Other services | 2018 |
| B Daniels Consultancy Ltd | Professional & scientific | 2025 |
| B Mann Heating and Plumbing Ltd | Construction | 2016 |
| B S K Maintenance Limited | Real estate | 2024 |
| B Smith Interiors Ltd | Construction | 2023 |
| B W Mouldings Limited | Construction | 2021 |
| B&C Hills Ltd | Hospitality | 2022 |
| B-Boy TV Ltd | Information & communication | 2012 |
| B.C.G Investments Limited | Financial services | 2020 |
| B.P.P. Technical Services Limited | Administrative & support | 1989 |
| B.T. Safety Ltd | Professional & scientific | 2019 |
| BACE21 Limited | Construction | 2021 |
| Baddowpharma Limited | Health & social care | 2024 |
| Bailiff Services Ltd | Professional & scientific | 2024 |
| Balanced Grid Solutions Limited | Professional & scientific | 2017 |
| Baldwin Signature Estates Ltd | Real estate | 2026 |
| BALIKCI47 Limited | Hospitality | 2025 |
| Baller$ Lounge Limited | Hospitality | 2022 |
| Ballers Elite Limited | Arts & recreation | 2019 |
| Ballgrove Limited | Professional & scientific | 2023 |
| Bamboo SW Investments Limited | Real estate | 2025 |
| Banks Home Improvements Limited | Construction | 2025 |
| Bardrock Limited | Construction | 2022 |
| Barnes Project Management Consultancy (Bpmc) Ltd | Construction | 2022 |
| Barns Initiative Limited | Real estate | 2018 |
| Barnwald Limited | Administrative & support | 1995 |
| Barrett Carpentry and Building Ltd | Construction | 2023 |
| Barrister Bismillah Limited | Professional & scientific | 2026 |
| Battlesbridge Events Limited | Administrative & support | 2011 |
| Bayanix Limited | Construction | 2003 |
| Baykut Optometry Ltd | Professional & scientific | 2015 |
| Bazzy H Limited | Health & social care | 2019 |
| BBG Property Limited | Construction | 2019 |
| Bbtouring Limited | Arts & recreation | 2025 |
| BC Electrical & Security Solutions Ltd | Administrative & support | 2021 |
| Bcln Ltd | Real estate | 2025 |