| AC Composites Limited | Manufacturing | 2018 |
| ACC Agriculture Ltd | Agriculture & fishing | 2019 |
| Access Platform Sales Holdings Limited | Professional & scientific | 2018 |
| Access Platform Service and Repair Limited | Construction | 2023 |
| Access Service & Maintenance Limited | Manufacturing | 2009 |
| Accolah Limited | Professional & scientific | 2014 |
| Accountancy & Statutory Services Limited | | 1987 |
| Accounts Simplified Limited | Professional & scientific | 2019 |
| Ace (Atherton Craigie Events) Ltd | Administrative & support | 2022 |
| Ace Finish Ltd | Manufacturing | 2009 |
| Ace Gain Limited | Arts & recreation | 2019 |
| Ace Web Services Limited | Information & communication | 2014 |
| Acecon Training Services Ltd | Education | 2019 |
| Aces Academies Trust | Education | 2011 |
| ACHIEVE24HEALTH Home Care Ltd | Administrative & support | 2025 |
| Achieving Lives Ltd | Health & social care | 1999 |
| ACI Retail Finance Limited | Wholesale & retail | 2016 |
| Acionna Therapeutics Ltd | Professional & scientific | 2025 |
| ACL Andulon Ltd | Transport & logistics | 2023 |
| Acmecloud Ltd | Information & communication | 2026 |
| Activinsights Holdings Limited | Financial services | 2024 |
| Acuerdo Ltd | Professional & scientific | 2019 |
| AD Thalia Limited | Professional & scientific | 2014 |
| Ad-Hoc Film Consultancy Limited | Information & communication | 2017 |
| Adagio Limited | Other services | 2013 |
| Adam J Cooper Ltd | Construction | 2015 |
| Adam Mills Roofing Limited | Construction | 2013 |
| Adansonia Homes Ltd | Real estate | 2023 |
| Adap Solutions Limited | Wholesale & retail | 2004 |
| Adaptacom Ltd | Professional & scientific | 2018 |
| Adaptaprop Limited | Construction | 2024 |
| Adaptive Accounts Limited | Professional & scientific | 2013 |
| ADB Dent Ltd | Health & social care | 2025 |
| Adeela Healthtech Limited | Health & social care | 2025 |
| Ademo Limited | Real estate | 2016 |
| Admiral Homespace Ltd | Construction | 2018 |
| Adrenaline Sports & Leisure Ltd | Arts & recreation | 2023 |
| Adrian M.G. Ltd | Administrative & support | 2019 |
| Advance Insurance Agencies Limited | Financial services | 2002 |
| Advanced Medical Resources Limited | Health & social care | 2024 |
| Advanced Mortgage Solutions Limited | Financial services | 2006 |
| Advanced Offsite Systems Limited | Construction | 2024 |
| Advanced Scientific Materials Acquico Limited | Professional & scientific | 2021 |
| Advanced Scientific Materials Limited | Professional & scientific | 2013 |
| Advanced Scientific Materials Pledgeco Limited | Professional & scientific | 2021 |
| Advanced Sterile Engineering Ltd | Professional & scientific | 2018 |
| Advanced Technology Ventures (UK) Ltd | Administrative & support | 2008 |
| Advicenet Limited | Professional & scientific | 2022 |
| Advocate Mortgage & Protection Ltd | Financial services | 2025 |
| AE Roofing Ltd | Extraterritorial | 2018 |
| Aeris Services Limited | Construction | 2015 |
| Aero Consultants (UK) Limited | Administrative & support | 1981 |
| Aeron Engineering Limited | Administrative & support | 2004 |
| Aerorea Limited | Administrative & support | 2013 |
| Aerostow Limited | Wholesale & retail | 2025 |
| AGG Consultants Limited | Administrative & support | 2012 |
| Agito Global Limited | Professional & scientific | 2022 |
| Agito Holdings Limited | Extraterritorial | 2020 |
| AGL Health Care Limited | Health & social care | 2022 |
| Agreserves Limited | Agriculture & fishing | 1994 |
| Agrieng Limited | Manufacturing | 2012 |
| Agrihire (Northampton) Limited | Administrative & support | 2018 |
| Agrobiothers LAB UK Limited | Administrative & support | 2021 |
| AGS Estates Ltd | Real estate | 2019 |
| Agsoftware Limited | Information & communication | 2017 |
| AH Appliance Repairs Ltd | Other services | 2021 |
| AH Chattha Ltd | Hospitality | 2025 |
| Ahadra Limited | Financial services | 2009 |
| AHM Motors Limited | Transport & logistics | 2019 |
| Ahmed & Siana Limited | Health & social care | 2024 |
| Ahmed Foods 24 Limited | Hospitality | 2025 |
| AI Ming Foods Limited | Hospitality | 2018 |
| Aigrette Financing (Issuer) PLC | Administrative & support | 2021 |
| Aigrette Financing Limited | Administrative & support | 2021 |
| Ailie Corporation Limited | Other services | 2016 |
| Ailynn Ltd | Transport & logistics | 2018 |
| Aim-Tti Holdings Limited | Financial services | 2013 |
| Air Rifle Hub Limited | Arts & recreation | 2025 |
| Air Sea & Land Asset Management Ltd | Real estate | 2025 |
| Aircover Limited | Construction | 2005 |
| Aircover(Uk) Limited | Construction | 2020 |
| Airdrop Productions Ltd | Professional & scientific | 2019 |
| Airfield Research Group Ltd | Arts & recreation | 2014 |
| Airframe Inspections Limited | Professional & scientific | 2025 |
| Airport Cabs Huntingdon Ltd | Transport & logistics | 2026 |
| Airtight Seal Ltd | Wholesale & retail | 2024 |
| AJC Window Cleaning Limited | Administrative & support | 2017 |
| AJM Building Contracts Ltd | Construction | 2013 |
| AJN Team Ltd | Transport & logistics | 2018 |
| AJR Joinery & Carpentry Ltd | Construction | 2023 |
| AJS Accountants Ltd | Professional & scientific | 2020 |
| Ak.Polservice Ltd | Wholesale & retail | 2020 |
| Aktogen Limited | Professional & scientific | 2003 |
| ALA Beauty & Co Ltd | Other services | 2025 |
| Alaina Homes Ltd | Real estate | 2019 |
| Alan's Carpets Limited | Construction | 2003 |
| Albert Mews Business Centre Limited | Professional & scientific | 1994 |
| Alceha Ltd. | Transport & logistics | 2019 |
| Alcon Flooring Limited | Construction | 2009 |
| Alconbrew Limited | Hospitality | 2023 |