| Acass Services Limited | Administrative & support | 2018 |
| ACB Busbar Ltd | Construction | 2025 |
| Access Hospitality Ltd | Administrative & support | 2024 |
| Accountancy & Business Improvement Ltd | Professional & scientific | 2004 |
| Accountancy Matters (South East) Limited | Extraterritorial | 2010 |
| ACD Audio Ltd | Professional & scientific | 2023 |
| Ace Kids Limited | Extraterritorial | 2025 |
| Ace With Spades Ltd | Administrative & support | 2023 |
| ACG Limited | Other services | 1982 |
| Achrzltd Ltd | Wholesale & retail | 2026 |
| Acreline Ltd | Information & communication | 2026 |
| Acro Property Services Limited | Construction | 2013 |
| Acropolis Aviation Limited | Transport & logistics | 2008 |
| Acrux Studio Ltd | Wholesale & retail | 2026 |
| Actfast Solutions Limited | Construction | 2009 |
| Actionize Limited | Professional & scientific | 2022 |
| Activefootprint Limited | Administrative & support | 2011 |
| AD Astra Associates Ltd | Information & communication | 2019 |
| AD Draughting Services Ltd | Professional & scientific | 2025 |
| AD HOC Freelance PA Limited | Administrative & support | 2013 |
| Adaptify Consulting Ltd | Professional & scientific | 2025 |
| Adaptive Infosec Ltd | Administrative & support | 2014 |
| Addlestone Properties Ltd | Transport & logistics | 2019 |
| Adeplast&Paint Ltd | Manufacturing | 2025 |
| Adhd Works Limited | Education | 2022 |
| Adhya Private Limited | Wholesale & retail | 2026 |
| Adjacent Consulting Limited | Professional & scientific | 2014 |
| ADM Technical Ltd | Construction | 2020 |
| Adrian Turner Podiatry Limited | Health & social care | 2015 |
| Adrien Darris Ltd | Health & social care | 2019 |
| Adrina Ltd | Real estate | 2024 |
| ADS Group Media Limited | Information & communication | 2026 |
| Advanced Material Development Limited | Professional & scientific | 2017 |
| Advanced Network Security Limited | Information & communication | 2003 |
| Advanced Valeting Centre Limited | Other services | 2013 |
| Advancing Growth Ltd | Professional & scientific | 2024 |
| Advantedge IT Solutions Ltd | Information & communication | 2016 |
| Adveco (AWP) Limited | Wholesale & retail | 1971 |
| Adveco Limited | Wholesale & retail | 2015 |
| Advised Financial Limited | Financial services | 2014 |
| Aedean Flooring Limited | Construction | 2008 |
| Aeleus Limited | Professional & scientific | 2004 |
| Aero Global Logistics Ltd | Transport & logistics | 2020 |
| Aerotex UK LLP | | 2002 |
| Aestechtic Ltd | Administrative & support | 2023 |
| Aesx Limited | Financial services | 2005 |
| AF Club 1 Limited | Arts & recreation | 2026 |
| AF Eagle EYE Limited | Wholesale & retail | 2022 |
| AF UK Corby Limited | Arts & recreation | 2026 |
| AF UK Cosham Limited | Arts & recreation | 2026 |
| AF UK Gateshead Limited | Arts & recreation | 2026 |
| AF UK Grantham Limited | Arts & recreation | 2026 |
| AF UK Kensington Limited | Arts & recreation | 2026 |
| AF UK Leeds Moor Allerton Limited | Arts & recreation | 2026 |
| AF UK Loughborough Limited | Arts & recreation | 2026 |
| Affina Organisation Development Limited | Professional & scientific | 2003 |
| Affinity Aviation Group Ltd | Transport & logistics | 2014 |
| Affluent Property Group Limited | Real estate | 2023 |
| Afraz Investments Limited | Administrative & support | 2016 |
| Afuk Holdings Limited | Other services | 2015 |
| Agile Coaching Ltd | Information & communication | 2018 |
| Agile Fleet Engineering Ltd | Wholesale & retail | 2023 |
| AGP87 Services Ltd | Transport & logistics | 2022 |
| AH Brompton Limited | Real estate | 2026 |
| Ah&Fj Ltd | Transport & logistics | 2019 |
| AI Internet Solutions Limited | Information & communication | 2009 |
| AI Vending Solutions Limited | Administrative & support | 2020 |
| Ailun Ecommerce and Import Export Limited | Wholesale & retail | 2025 |
| Aimpro Services Ltd | Financial services | 2026 |
| Aims Team Ltd | Information & communication | 2025 |
| Air Charter Corporation Limited | Extraterritorial | 2006 |
| Air-Modification Limited | Construction | 2013 |
| Aircraft Chartering Services Limited | Transport & logistics | 1986 |
| Airops Software Limited | Information & communication | 1989 |
| Airport Cruise Pickups Limited | Transport & logistics | 2024 |
| Airside Airport Equipment Thorough Examinations Limited | Professional & scientific | 2009 |
| AJ5 Events Ltd | Administrative & support | 2026 |
| AJJ Surveying & Consultancy Limited | Professional & scientific | 2026 |
| AJT Landscaping Limited | Administrative & support | 2019 |
| AK Alloys Ltd | Wholesale & retail | 2014 |
| Aker Solutions DC Trustees Limited | Professional & scientific | 2004 |
| AKG Electrical Contractors Limited | Construction | 2021 |
| Alan Clayton Design Ltd | Administrative & support | 2006 |
| Alan Hocking Associates Ltd | Manufacturing | 2024 |
| ALB Intensive Driving Ltd | Education | 2023 |
| Albion Infrastructure Limited | Professional & scientific | 2008 |
| Albon Jobs Ltd | Administrative & support | 2024 |
| Aldershot Masonic Properties Limited | Other services | 1961 |
| Alex MAY Hughes Ltd | Arts & recreation | 2022 |
| Alex Smith Fitness Ltd | Education | 2025 |
| Alexander Mansell Limited | Professional & scientific | 2009 |
| Alexander Park Homes Limited | Health & social care | 2006 |
| Alexander Residential Limited | Real estate | 2009 |
| Alexander Seymour Ltd | Real estate | 2021 |
| Alexander's Supported Living Ltd | Health & social care | 2016 |
| Alexander’S Mental Health Ltd | Health & social care | 2016 |
| Alexander’S Residential Care Ltd | Extraterritorial | 2017 |
| Alexandra Hall (Functions & Events) Ltd | Hospitality | 2014 |
| Alexandra House Offices Ltd | Real estate | 2013 |
| Alexandra Road Management Company Limited | Households | 1981 |