| Alcmaeon Medical Communications Ltd | Professional & scientific | 2013 |
| Alcott Psychology Services Limited | Health & social care | 2012 |
| Alder Electrical Services Ltd | Construction | 2020 |
| Alderbrook Consulting Limited | Professional & scientific | 1997 |
| Aldershot Healthcare Investments Limited | Real estate | 2004 |
| Aldershot Management Company Limited | Households | 2014 |
| Aldis Law Limited | Professional & scientific | 2014 |
| Alessa Gourme-Tea Limited | Wholesale & retail | 2025 |
| Alessandro Rossi Ltd | Wholesale & retail | 2022 |
| Alex Bevan Arbitration Ltd | Administrative & support | 2025 |
| Alex Ells Ltd | Other services | 2019 |
| Alex Hippisley-Cox PR Ltd | Professional & scientific | 2012 |
| Alexa Lily Limited | Manufacturing | 2024 |
| Alexander Bathrooms Limited | Construction | 2018 |
| Alexander Harding Ltd | Financial services | 2011 |
| Alexander Marsh Garden Services Limited | Administrative & support | 2021 |
| Alexandra Mews Residents Association Limited | Real estate | 1996 |
| ALF Alpha Limited | Financial services | 2025 |
| Alfonso Cruz Ltd | Professional & scientific | 2017 |
| ALG Consulting Services Limited | Professional & scientific | 2015 |
| ALI and Sons Real Estate Ltd | Real estate | 2025 |
| ALI Cabling Ltd | Construction | 2025 |
| ALI Food & Butchers Ltd | Wholesale & retail | 2014 |
| ALI Spice House Ltd | Hospitality | 2025 |
| Alice Consulting Limited | Administrative & support | 2014 |
| Alison Claire Limited | Construction | 2005 |
| Alive and Cooking Limited | Hospitality | 2012 |
| Alkhalaf & Sons Ltd | Real estate | 2019 |
| Alkimique Ltd | Wholesale & retail | 2025 |
| ALL 4 Homes Construction Ltd | Construction | 2026 |
| ALL About Caring Ltd. | Health & social care | 2012 |
| ALL Altitude Group Services Limited | Financial services | 2020 |
| ALL Fired UP Heating Limited | Wholesale & retail | 2007 |
| ALL in Homes Ltd | Real estate | 2025 |
| ALL OUR Business Limited | Professional & scientific | 2003 |
| Alldens Limited | Construction | 2019 |
| Allegiance Global Investments (UK) Limited | Real estate | 1998 |
| Allerthorpe Education Limited | Education | 2023 |
| Allerton Communications Limited | Professional & scientific | 2008 |
| Allied Electrical Limited | Construction | 2020 |
| Allingham Meadow Limited | Households | 2022 |
| Allostasis Ltd | Information & communication | 2026 |
| Alloy Ltd | Professional & scientific | 1998 |
| Alltype Roofing Supplies (Group) Limited | Wholesale & retail | 2019 |
| Almeric Holdings Ltd | Financial services | 2026 |
| Almond House (Edenbrook) Management Company Limited | Households | 2021 |
| Alpha and Omega Church - Stratford | Other services | 2018 |
| Alpha Group (Surrey) Limited | Construction | 2022 |
| Alpha Medical Solutions Limited | Health & social care | 2012 |
| Alpha Roofing Group Limited | Construction | 2025 |
| Alpha Taxis Ltd | Transport & logistics | 2019 |
| Alpha Welding Ltd | Manufacturing | 2023 |
| Alston Elliot Limited | Information & communication | 1992 |
| Alsyra Ltd | Public administration | 2026 |
| Altitude Accounting Limited | Professional & scientific | 2018 |
| Altitude Addventures Limited | Professional & scientific | 2020 |
| Altitude Advisory Limited | Professional & scientific | 2018 |
| Altitude Ascension Ltd | Wholesale & retail | 2024 |
| Altitude Lofts Limited | Professional & scientific | 2017 |
| Altivus Vitae Ltd | Information & communication | 2025 |
| Alto Consulting Group LLP | | 2019 |
| Altrades Packaging Ltd | Administrative & support | 2021 |
| Altus Digital Limited | Information & communication | 2013 |
| Altus Media Limited | Information & communication | 2024 |
| Altus Ventures Group Limited | Financial services | 2023 |
| Altus Ventures Limited | Information & communication | 2013 |
| Altyne Limited | Real estate | 1995 |
| Alukov UK Ltd. | Construction | 2005 |
| Aluvise Consulting Limited | Professional & scientific | 2024 |
| Aluvita Limited | Construction | 2023 |
| Alveare Ltd | Mining & quarrying | 2019 |
| Alvi Estate Group Construction Ltd | Construction | 2022 |
| Alward Advisory Services Ltd | Professional & scientific | 2026 |
| AM Sports Management Ltd | Arts & recreation | 2025 |
| AMA Painters Ltd | Construction | 2016 |
| Amadou Consulting Limited | Information & communication | 2025 |
| Amanzi Laundry Ltd | Other services | 2025 |
| Amari Lets Ltd | Hospitality | 2023 |
| Amartex Limited | Administrative & support | 2012 |
| Amawaterways Limited | Administrative & support | 2016 |
| Amaze Logistics Ltd | Transport & logistics | 2025 |
| Amazing Contractors Limited | Construction | 2016 |
| Ambassador Band Ltd | Arts & recreation | 2014 |
| Amber Projects (Bramley) Limited | Construction | 2023 |
| Amberley Aromatics Limited | Manufacturing | 2010 |
| Amberley Holdings Ltd | Real estate | 2015 |
| Ambmgt Ltd | Other services | 2016 |
| Ambr Developments Ltd | Construction | 2024 |
| Amchaluka Limited | Financial services | 2022 |
| AMD Consulting Limited | Other services | 2011 |
| Amega Electronics Limited | Professional & scientific | 1987 |
| Amega Group Limited | Professional & scientific | 1987 |
| Amelia (Ipsoft UK) Limited | Information & communication | 2004 |
| Amelia Nancy Tant Properties Limited | Real estate | 2020 |
| Amelior Consulting Limited | Professional & scientific | 2015 |
| Ameliorate Investment Company | Financial services | 2025 |
| Amethyst Accountancy Limited | Other services | 2017 |
| AMG Cars Limited | Transport & logistics | 2018 |
| Amico Polishing Ltd | Manufacturing | 2011 |
| Amida Limited | Administrative & support | 2009 |