| Adrian Metcalfe Transport Ltd | Transport & logistics | 2015 |
| Adroc Healthcare Limited | Other services | 2012 |
| ADS Property Development Limited | Construction | 2020 |
| ADS2 Property LLP | | 2015 |
| Advanced Body Aesthetics Limited | Other services | 2018 |
| Advanced Energy Storage Ltd | Energy | 2022 |
| Advanced Technology Services, UK Limited | Other services | 2007 |
| Advanced Urban Ltd | Construction | 2026 |
| Advancedchem Limited | Administrative & support | 2019 |
| ADVANCEDK9SOLUTIONS Limited | Administrative & support | 2014 |
| Adville Limited | Construction | 1998 |
| ADY Network Ltd | Transport & logistics | 2022 |
| Adyant Electrical Services Limited | Construction | 2010 |
| AEA Growth Ltd | Professional & scientific | 2025 |
| Aebp Walling Limited | Extraterritorial | 1985 |
| AEG Property Ltd | Real estate | 2023 |
| Aegis Risk Management Ltd | Administrative & support | 2022 |
| Aegisearth Ltd | Construction | 2020 |
| Aesthetically Pleasing Aesthetics Ltd | Other services | 2020 |
| Aesthetics by Toetie Limited | Wholesale & retail | 2024 |
| AFA Engineering Consultancy Limited | Construction | 2024 |
| Afac Associates Ltd | Information & communication | 2012 |
| AFC Rushden & Diamonds Youth C.I.C. | Arts & recreation | 2007 |
| Affordable Plumbing and GAS Limited | Professional & scientific | 2026 |
| AFG Transport Ltd | Administrative & support | 2008 |
| AFL Electrical Ltd | Construction | 2019 |
| Afmac Limited | Professional & scientific | 2015 |
| AFP EBT Limited | Financial services | 2021 |
| AFP Product Reaction Limited | Wholesale & retail | 2022 |
| AFP Services Limited | Professional & scientific | 2002 |
| Africa Exclusive Limited | Administrative & support | 1990 |
| Africa Safari Connections Ltd | Administrative & support | 2023 |
| Afrock Holdings Ltd | Transport & logistics | 2024 |
| Agape Shine Cleaning Services Ltd | Administrative & support | 2025 |
| Agile Distribution Ltd | Wholesale & retail | 2025 |
| Agiz Construction Ltd | Construction | 2015 |
| Agiz Home Improvements Ltd | Construction | 2022 |
| AGM Chilled Transport Limited | Transport & logistics | 2021 |
| Agrarius Limited | Information & communication | 2010 |
| AGS Investments & Management Limited | Financial services | 2025 |
| AGS Management & Consultancy Limited | Professional & scientific | 2022 |
| AH Builders Ltd | Construction | 2012 |
| Ahlc Holdings Ltd | Financial services | 2020 |
| AI Bridge Solutions Limited | Information & communication | 2024 |
| Aibp 2 Limited | Extraterritorial | 1986 |
| Aicconstruction Ltd | Professional & scientific | 2023 |
| AIM Supply Chain Management Limited | Wholesale & retail | 1999 |
| Aimee's Limited | Wholesale & retail | 2015 |
| Aimtech Business Services Ltd | Information & communication | 2020 |
| Aimtech Group Holdings Ltd | Financial services | 2024 |
| Ainj Group Ltd | Professional & scientific | 2026 |
| Airspace Studio Ltd | Construction | 2023 |
| AJG Design and Build Ltd | Construction | 2015 |
| AJK Vehicle Services Limited | Wholesale & retail | 2018 |
| AJL Safety Solutions Limited | Professional & scientific | 2025 |
| Ajmh Consulting Ltd | Professional & scientific | 2023 |
| AJR Automotive Ltd | Wholesale & retail | 2019 |
| AJR Contracting Services Ltd | Information & communication | 2024 |
| AJS & Matchless Owners Club Limited | Other services | 2003 |
| Ajsourcing Limited | Real estate | 2025 |
| AJT Plumbing and Heating Ltd | Construction | 2023 |
| AJW Plant & Haulage Limited | Transport & logistics | 2015 |
| AK Exports Ltd | Wholesale & retail | 2018 |
| AKJ Motorsport Ltd | Wholesale & retail | 2020 |
| Akpb Ltd | Wholesale & retail | 2026 |
| Akreativ Limited | Information & communication | 2014 |
| Akuna Corporate Limited | Real estate | 2023 |
| Akuna Fitout Limited | Construction | 2023 |
| Akuna I Limited | Construction | 2023 |
| Akuna Leasehold Limited | Real estate | 2026 |
| Akuna Property Limited | Real estate | 2022 |
| AKW Aesthetics Ltd | Other services | 2022 |
| AL Hawthorn Properties Limited | Real estate | 2025 |
| Aladekoyi Consulting Limited | Professional & scientific | 2025 |
| Alan Currall Ltd | Other services | 2013 |
| Alat Living Ltd | Real estate | 2025 |
| Albero Ltd | Information & communication | 2025 |
| Albert Electrical Services Limited | Construction | 2024 |
| Albertina Fisher Ltd | Health & social care | 2018 |
| Albone Partnerships Ltd | Real estate | 2023 |
| Aldea Group UK Limited | Wholesale & retail | 2020 |
| Alder Construction Solutions Ltd | Construction | 2025 |
| Aldervane Holdings Ltd | Financial services | 2026 |
| Alderwood Ecology Limited | Other services | 2026 |
| Alderwood Property Ltd | Construction | 2025 |
| Aldryn Property & Asset Management Ltd | Real estate | 2026 |
| Aldwincle Stores Limited | Wholesale & retail | 2026 |
| Alec’S Tours Ltd | Transport & logistics | 2021 |
| Alex Plus Ltd | Transport & logistics | 2024 |
| Alex&Co Properties Limited | Real estate | 2020 |
| Alexanders Housing Limited | Real estate | 2024 |
| Alexcom Ltd | Administrative & support | 2018 |
| Alex’S Blue Sky Ltd | Hospitality | 2024 |
| Alfred Power Consultancy Limited | Other services | 2016 |
| Alfy Jack Training Limited | Construction | 2026 |
| Algora Homes Ltd | Real estate | 2016 |
| Align and Change Consulting Ltd | Professional & scientific | 2026 |
| Align Scaffolding Ltd | Construction | 2026 |
| Aligner Ltd | Health & social care | 2015 |
| ALK Limited | Extraterritorial | 1946 |