| Alliadis Europe Ltd. | Professional & scientific | 2004 |
| Alliance Engineering Limited | Extraterritorial | 2024 |
| Allied Global Safety Ltd | Manufacturing | 2025 |
| Allmark IT Limited | Information & communication | 2014 |
| Allsaints Ltd | Manufacturing | 2005 |
| Allsort Creations Limited | Wholesale & retail | 2024 |
| Allthe Ltd | Manufacturing | 2023 |
| Allura Ltd | Other services | 2019 |
| Almond & Murtagh Plumbing and Heating Services Limited | Construction | 2022 |
| Almond Homes Ltd | Real estate | 2019 |
| Alnimanui Healthcare Ltd | Health & social care | 2018 |
| Alpha Associates Recruitment Ltd | Administrative & support | 2020 |
| Alpha Creative Design Ltd | Professional & scientific | 2020 |
| Alpha Resin Surfaces Limited | Construction | 2025 |
| Alston Acquisitions Limited | Professional & scientific | 2013 |
| Alston Group Holdings Limited | Financial services | 2025 |
| Alston Investments Holdings Limited | Financial services | 2021 |
| Alston Investments Limited | Professional & scientific | 2014 |
| Alston Properties Limited | Real estate | 2002 |
| ALT Commercials Ltd | Wholesale & retail | 2026 |
| Altos Transport Ltd | Transport & logistics | 2020 |
| Alty Grab Hire Limited | Transport & logistics | 2018 |
| Aluna MAE Ltd | Wholesale & retail | 2021 |
| Always Knitting and Sewing Limited | Wholesale & retail | 2011 |
| AM Solar & Electrical Ltd | Construction | 2023 |
| Amaco Waste Management & Recycling Ltd | Water & waste | 2024 |
| Amalgamated Euro Products UK Ltd | Manufacturing | 2012 |
| Amanda Englishby Ltd | Health & social care | 2021 |
| Amber Catering London Ltd | Hospitality | 2017 |
| Ambohoist Ltd | Manufacturing | 2021 |
| AMC Electrical Contractors (NW) Limited | Construction | 2021 |
| American PIE UK Limited | Transport & logistics | 2006 |
| Ames (South West) Limited | Construction | 2017 |
| Amigos Chorley Ltd | Hospitality | 2026 |
| Amigos Smash Limited | Hospitality | 2025 |
| Amjc Holdings Limited | Professional & scientific | 2014 |
| AMN Travel Services Ltd | Administrative & support | 2023 |
| AMP GAS Services Ltd | Construction | 2019 |
| Ampersand (Y2K) Ltd | Wholesale & retail | 1998 |
| AMS Technical (Plastics) Limited | Manufacturing | 2014 |
| Amusement Technical Rentals Limited | Administrative & support | 2008 |
| Anabat Limited | Professional & scientific | 2012 |
| Ananda Retreats Hosting Ltd | Administrative & support | 2023 |
| Ananda Yoga Retreats Ibiza Ltd | Other services | 2023 |
| Ananda Yoga Retreats Ltd | Other services | 2017 |
| Anapata Ltd | Hospitality | 2020 |
| Anchor Alliance CIC | Health & social care | 2025 |
| Anchor Neuro Tech Ltd | Health & social care | 2026 |
| Anchor PIN Engineering Limited | Wholesale & retail | 1984 |
| Andbeauty Limited | Wholesale & retail | 2020 |
| Anderson Brookes Business Finance Ltd | Financial services | 2019 |
| Anderson Brookes Holdings Ltd | Financial services | 2024 |
| Anderson Brookes Insolvency Practitioners Ltd | Administrative & support | 2016 |
| Anderson Brookes Ltd | Financial services | 2001 |
| Anderton Day Nursery Limited | Health & social care | 2011 |
| Andoro Distributions Ltd | Wholesale & retail | 2025 |
| Andrew Foster-Yeow Ltd | Professional & scientific | 2018 |
| Andrew Holden Services Limited | Wholesale & retail | 2023 |
| Andrew John Hill Ltd | Financial services | 2025 |
| Andrew Palmer Golf Ltd | Professional & scientific | 2025 |
| Andrew Pooley Limited | Construction | 2002 |
| Andrew Pope Driving Limited | Education | 2015 |
| Andrew Williams Group Limited | Construction | 2019 |
| Andrew's Cleaning Service Limited | Administrative & support | 2000 |
| Andy Harrison Transport Ltd | Transport & logistics | 2020 |
| Andy's Driver Hire Limited | Transport & logistics | 2014 |
| Andys Autos (North West) Limited | Wholesale & retail | 2015 |
| Anglezarke Building Consultancy Ltd | Administrative & support | 2016 |
| Anglezarke Distillery Ltd | Manufacturing | 2026 |
| Anglezarke Investments Limited | Real estate | 1970 |
| Anglezarke Leisure Services Ltd | Construction | 2016 |
| Anglezarke U.K Ltd | Construction | 2023 |
| Anglia Papercraft Limited | Manufacturing | 1970 |
| Anglia Shunters Limited | Transport & logistics | 1911 |
| Anglin Associates Limited | Extraterritorial | 2015 |
| Animalique Therapy Limited | Professional & scientific | 2016 |
| Aniras Holdings UK Limited | Professional & scientific | 2025 |
| Anita Tunstall Ltd | Other services | 2019 |
| Anme Limited | Information & communication | 2014 |
| ANN Blyth & SON Funeral Directors Limited | Professional & scientific | 2009 |
| Anna Kathryn Lynch Limited | Arts & recreation | 2023 |
| Anna Recruits Ltd | Administrative & support | 2020 |
| Annaac Limited | Information & communication | 2012 |
| Annal Professional Care Ltd | Health & social care | 2014 |
| Anncraig Ltd | Health & social care | 2013 |
| Annie Lane Limited | Other services | 2017 |
| Anor AI Limited | Information & communication | 2025 |
| ANP Satellites Ltd | Information & communication | 2018 |
| Ansari Homes Ltd | Real estate | 2024 |
| Antboyuk Ltd | Wholesale & retail | 2023 |
| Antec Engineering Services Ltd | Manufacturing | 2016 |
| Anxsur Ltd | Other services | 2024 |
| AO Electrotech Ltd | Construction | 2019 |
| AOS Limited | Real estate | 1971 |
| AP Equipment Limited | Manufacturing | 2024 |
| APA Water Resources Limited | Extraterritorial | 2012 |
| Apex 123 Ltd | Manufacturing | 2014 |
| Apex Groundworks & Civils Ltd | Administrative & support | 2022 |
| Apex the Division Security Solutions Limited | Administrative & support | 2023 |
| Apex Theory Limited | Wholesale & retail | 2025 |