| ALL That Matters Digital Ltd | Information & communication | 2024 |
| ALL the Best Barber Ltd | Other services | 2018 |
| ALL the Kids Limited | Wholesale & retail | 2021 |
| ALL the Rage Ltd | Arts & recreation | 2024 |
| ALL Things Digital Limited | Other services | 2013 |
| ALL Things Ginger Ltd | Manufacturing | 2025 |
| ALL Trade Distributors Ltd | Wholesale & retail | 2026 |
| ALL UK Businesses Ltd | Extraterritorial | 2020 |
| ALL Waste Remove Ltd | Transport & logistics | 2025 |
| ALL Weather Roofing West Midlands Ltd | Construction | 2023 |
| All-Line Ltd | Wholesale & retail | 2023 |
| ALL41 Group Ltd | Wholesale & retail | 2025 |
| Allaboutcarz Ltd | Wholesale & retail | 2021 |
| Allabouttrends Limited | Information & communication | 2020 |
| Allah Deen Ltd | Wholesale & retail | 2025 |
| Allah Ditta Catering Limited | Hospitality | 2014 |
| Allahditta Ltd | Wholesale & retail | 2020 |
| Allai Limited | Health & social care | 2012 |
| Allamagan Shop Ltd | Wholesale & retail | 2021 |
| Allamo Services Ltd | Manufacturing | 2007 |
| Allan F Holland & Sons Limited | Other services | 2010 |
| Allan Jones Properties Ltd | Construction | 2022 |
| Allan Morris & Peace Limited | Real estate | 2007 |
| Allan Ricketts & Sons Limited | Wholesale & retail | 1977 |
| Allbrik Estates Ltd | Real estate | 2025 |
| Allcam Investment Limited | Real estate | 2013 |
| Allcam Mobile Products Limited | Wholesale & retail | 2002 |
| Allcare Medical Group Limited | Wholesale & retail | 2025 |
| Allclear Clearances Ltd | Transport & logistics | 2025 |
| Allcroft Motors Ltd | Wholesale & retail | 2024 |
| Allday Essentials Ltd | Wholesale & retail | 2025 |
| Alldos (UK) Limited | Manufacturing | 1996 |
| Alldrive Ltd | Information & communication | 2025 |
| Allecons Limited | Information & communication | 2018 |
| Allegiant Global Services (UK), Limited | Water & waste | 2008 |
| Allegion (UK) Limited | Manufacturing | 1889 |
| Allegion Investments (UK) Limited | Administrative & support | 2008 |
| Allegro Properties Ltd | Real estate | 2021 |
| Allely Edge Property Services Limited | Administrative & support | 2013 |
| Allen Fintech Limited | Professional & scientific | 2021 |
| Allen IP Limited | Professional & scientific | 2008 |
| Allen's Fishing Tackle Limited | Wholesale & retail | 1999 |
| Allenco Worldwide (Freight Management) Limited | Transport & logistics | 2001 |
| Allendale Solutions Ltd | Hospitality | 2022 |
| Allens 03 (Poultry) Limited | Wholesale & retail | 2003 |
| Allens Cross Ltd | Wholesale & retail | 2025 |
| Allerbray Limited | Professional & scientific | 2018 |
| Allerton & Gladstone AID Ltd | Other services | 2023 |
| Allerton & Gladstone Ltd | Professional & scientific | 2020 |
| ALLES1688 Limited | Wholesale & retail | 2018 |
| Allesley Fryer Limited | Hospitality | 2012 |
| Allesley Ltd | Real estate | 2010 |
| Alleswell Consulting Ltd | Professional & scientific | 2020 |
| Allevard Springs Limited | Manufacturing | 1990 |
| Alleviate Therapy Ltd | Other services | 2025 |
| Allexpress Ltd | Transport & logistics | 2016 |
| Alley Cat Ltd | Administrative & support | 2016 |
| Allfaith Ltd | Other services | 2025 |
| Allflip Limited | Construction | 2025 |
| Allflyghts Ltd | Information & communication | 2025 |
| Allfood Wholesale Ltd | Wholesale & retail | 2025 |
| Allgood Holdings Ltd | Wholesale & retail | 1940 |
| Allgood Limited | Wholesale & retail | 1987 |
| Allgood Manufacturing Limited | Manufacturing | 1995 |
| Allgood Secure Ltd | Wholesale & retail | 1982 |
| Allgoods Inc Ltd | Wholesale & retail | 2023 |
| Alliance Actimel Ltd | Administrative & support | 2019 |
| Alliance Audit and Survey Limited | Extraterritorial | 2009 |
| Alliance Automotive Investment Limited | Wholesale & retail | 2014 |
| Alliance Automotive UK CV Limited | Wholesale & retail | 1987 |
| Alliance Automotive UK Limited | Professional & scientific | 1997 |
| Alliance Automotive UK LV Limited | Wholesale & retail | 1970 |
| Alliance Capital Ltd | Real estate | 2006 |
| Alliance Care Support Ltd | Administrative & support | 2022 |
| Alliance Cashflow Limited | Extraterritorial | 2008 |
| Alliance Clinical Consulting Ltd | Health & social care | 2025 |
| Alliance Clinical Services Limited | Health & social care | 2021 |
| Alliance Commercial Finance Limited | Financial services | 2008 |
| Alliance Electrical Trading Limited | Wholesale & retail | 2015 |
| Alliance Engineering Group Ltd | Construction | 2016 |
| Alliance Financial Recruitment Limited | Extraterritorial | 2009 |
| Alliance Fulfilment Ltd | Wholesale & retail | 2019 |
| Alliance GAS & Recertification Ltd | Professional & scientific | 2021 |
| Alliance Goods Ltd | Wholesale & retail | 2023 |
| Alliance Group Properties Ltd | Real estate | 2024 |
| Alliance Health Group Limited | Health & social care | 2015 |
| Alliance Health PMI Limited | Financial services | 2021 |
| Alliance Housing Solutions Ltd | Real estate | 2021 |
| Alliance Investments and Holdings Ltd | Financial services | 2024 |
| Alliance Invoice Finance Limited | Extraterritorial | 2013 |
| Alliance Medical Indemnity Limited | Financial services | 2011 |
| Alliance of Green Builders Ltd | Construction | 2024 |
| Alliance Pallets Group Limited | Manufacturing | 2025 |
| Alliance Sales Limited | Manufacturing | 2003 |
| Alliance Social Housing Limited | Hospitality | 2025 |
| Alliance Sports Capital Limited | Extraterritorial | 2009 |
| Alliance Supported Housing Ltd | Real estate | 2022 |
| Alliance Surgical Corporate Health Limited | Health & social care | 2012 |
| Alliance Surgical Indemnity Limited | Extraterritorial | 2011 |
| Alliance Surgical Investments Limited | Health & social care | 2004 |