| Alr&Jo Ltd | Construction | 2015 |
| Alse Limited | Wholesale & retail | 2021 |
| Alse London Limited | Wholesale & retail | 2021 |
| Alse Ventures Limited | Construction | 2025 |
| ALT Berg Group Limited | Financial services | 2021 |
| ALT Berg Holdings Limited | Financial services | 2012 |
| ALT Berg Limited | Manufacturing | 1990 |
| Altered Visuals Ltd | Information & communication | 2025 |
| Alto Digital Media Ltd | Administrative & support | 2017 |
| Altor Group Ltd | Financial services | 2026 |
| Altura Advisory Limited | Professional & scientific | 2025 |
| Altura Brands Ltd | Wholesale & retail | 2025 |
| Altus PM Limited | Households | 2025 |
| Alumina Investments Ltd | Real estate | 2022 |
| Always Back a Grey Horse Limited | Hospitality | 2022 |
| Always Buying Property Ltd | Real estate | 2020 |
| Always Independent Financial Solutions Limited | Professional & scientific | 2007 |
| ALY Khairuddin Ltd | Professional & scientific | 2025 |
| AM Radiology Ltd | Health & social care | 2021 |
| AMA Marketing Solutions Ltd | Professional & scientific | 2025 |
| AMA Music Ltd | Arts & recreation | 2021 |
| Amaar Real Estate Ltd | Real estate | 2024 |
| Amadeus River Cruises Ltd | Administrative & support | 2024 |
| Amalgamated Taxis Ltd | Transport & logistics | 2025 |
| Amaluna Holdings Limited | Real estate | 2018 |
| Amanda Edge (Dentist) Limited | Health & social care | 2020 |
| Amanda Lamb Limited | Information & communication | 2022 |
| Amaryllisprojects Ltd | Construction | 2021 |
| Amazed Limited | Manufacturing | 2003 |
| Amazonas Comics Community Interest Company | Education | 2019 |
| Amber Lane Press Limited | Information & communication | 1979 |
| Amber's Pour Ltd | Hospitality | 2026 |
| Ambercraft Residents Association Limited | Households | 1991 |
| AME Mineral Economics Limited | Administrative & support | 2024 |
| Ameenco Property Limited | Real estate | 2020 |
| American Sky Limited | Professional & scientific | 2006 |
| American Steamboat International GSA Limited | Administrative & support | 2012 |
| Amicable Apps Ltd. | Information & communication | 2015 |
| Amkay Traders Ltd | Wholesale & retail | 2024 |
| Amnam Ltd | Health & social care | 2011 |
| Amontola Richmond Ltd | Hospitality | 2016 |
| Amor Optical Limited | Wholesale & retail | 2021 |
| Amorworks Ltd | Professional & scientific | 2020 |
| Amos International London Limited | Administrative & support | 2014 |
| Amphibian Scuba & Snorkelling Centre Ltd | Wholesale & retail | 2019 |
| Amplify Education Group Limited | Professional & scientific | 2018 |
| Amplus Consulting Ltd | Information & communication | 2023 |
| Ampoweruk Ltd | Energy | 2016 |
| AMS Consulting Limited | Professional & scientific | 2020 |
| AMY Harrison Studios Ltd | Arts & recreation | 2023 |
| AN Supply Co. Ltd | Wholesale & retail | 2026 |
| Analogue Coaching Ltd | Professional & scientific | 2018 |
| Analyst Investments Limited | Financial services | 1998 |
| Anand Clan Ltd | Information & communication | 2023 |
| Anar Capital Limited | Financial services | 2020 |
| Anatoa Ltd | Manufacturing | 2026 |
| Ancaster Management Limited | Professional & scientific | 2017 |
| Anderson & Orchard Ltd | Education | 2026 |
| Anderson Wallace Ltd | Real estate | 2008 |
| Andfinally Ltd | Information & communication | 2024 |
| Andrew Skene & Associates Limited | Administrative & support | 2013 |
| Andrew Stern Communications Limited | Professional & scientific | 2025 |
| Andrew Williamson UK Ltd | Construction | 2004 |
| Andy Clark Television Lighting Limited | Arts & recreation | 2012 |
| Andy Whiteside Carpentry Ltd | Manufacturing | 2023 |
| Anella Limited | Financial services | 2016 |
| Anemos Homes Limited | Professional & scientific | 1983 |
| ANG Design Ltd | Professional & scientific | 2018 |
| Angel Assured Tenancy Limited | Real estate | 1990 |
| Angel Car Hire Ltd | Transport & logistics | 2024 |
| Angel Morgan Limited | Real estate | 1989 |
| Angel's Partners Ltd | Other services | 2023 |
| Angel's Private Limited | Wholesale & retail | 2020 |
| Angelfish Creations Ltd | Information & communication | 2021 |
| Angelpie Limited | Professional & scientific | 2017 |
| Angels Academy Nursery Ltd | Education | 2026 |
| Angie Carr Associates Ltd | Professional & scientific | 2005 |
| Anglo Saxon Legal Limited | Professional & scientific | 2009 |
| Anifa Cole Consulting Limited | Health & social care | 2014 |
| Animal Orthopaedics Limited | Professional & scientific | 2014 |
| Anitosh Technology Solutions Ltd | Information & communication | 2013 |
| Annabel Hobley Limited | Information & communication | 2024 |
| Annabel Westman Limited | Administrative & support | 2003 |
| Anne Heal & Associates Limited | Professional & scientific | 2016 |
| Annecy Home Designs Limited | Wholesale & retail | 2017 |
| Ante-Bellum Group Limited | Other services | 2026 |
| Anthony Blanco Limited | Information & communication | 2018 |
| Anthony Johnson Construction Ltd | Construction | 2017 |
| Anthony Smith Advertising Ltd | Professional & scientific | 2006 |
| Antidote Bidco Limited | Financial services | 2018 |
| Antidote Investor Holdco Limited | Financial services | 2018 |
| Antidote Topco Limited | Financial services | 2018 |
| Anwar Brothers Limited | Financial services | 2007 |
| APE Tree Services Ltd | Agriculture & fishing | 2025 |
| Apex Doodles Ltd | Arts & recreation | 2025 |
| Apexchroma Limited | Information & communication | 2024 |
| Appella Recruitment Limited | Administrative & support | 2012 |
| Appfluo Ltd | Information & communication | 2023 |
| Apple J Sound Limited | Information & communication | 2008 |
| Apple Orceard Ltd | Hospitality | 2023 |