| ALM Consultants Ltd | Professional & scientific | 2025 |
| Alma Management Services Ltd | Real estate | 2019 |
| Alocke Ltd | Professional & scientific | 2022 |
| Alpha Lighting and Electrical Limited | Wholesale & retail | 2021 |
| Alpha Merchants Ltd | Wholesale & retail | 2019 |
| Alpha Zulu Whiskey Limited | Professional & scientific | 2022 |
| Alpine Rush Limited | Administrative & support | 2025 |
| Alpine Water UK Limited | Hospitality | 2020 |
| Alta Vista Consultancy Ltd | Professional & scientific | 2025 |
| Altecopia Company Limited | Administrative & support | 2001 |
| Aluminium Extrusions Limited | Information & communication | 2000 |
| Aluta Quality Consultancy Ltd | Professional & scientific | 2024 |
| Alva Consult UK Ltd | Professional & scientific | 2019 |
| AM Projects Group Ltd | Information & communication | 2020 |
| AM Residents Limited | Households | 2025 |
| Amadeus Controls Limited | Construction | 2021 |
| Amarchive Ltd | Professional & scientific | 2024 |
| AMB Carpentry Ltd | Construction | 2022 |
| Amber Signs Berkhamsted Ltd | Manufacturing | 2014 |
| Amberfertility Ltd | Health & social care | 2024 |
| Amberley Garden Services Limited | Administrative & support | 2015 |
| Amberside Capital Ltd | Financial services | 2015 |
| Amberside Holdings Ltd | Financial services | 2022 |
| Amberside Nominees Ltd | Professional & scientific | 2018 |
| Amberside Valuations Holdings Ltd | Financial services | 2022 |
| Amberside Valuations Ltd | Professional & scientific | 2018 |
| Ambunti Partnership Limited | Wholesale & retail | 2017 |
| Amelia Illustration Limited | Arts & recreation | 2018 |
| Amer Properties Limited | Real estate | 2012 |
| Amersham Movers Ltd | Transport & logistics | 2025 |
| Amerton Holdco Limited | Professional & scientific | 2013 |
| Aminco Limited | Agriculture & fishing | 2000 |
| AMP Real Estate Ltd | Construction | 2020 |
| AMY Nuala Hair Ltd | Other services | 2022 |
| Ancraic Holdings Limited | Professional & scientific | 2022 |
| Anderson Retail Consulting Limited | Professional & scientific | 2026 |
| Andy Smith Creative Limited | Professional & scientific | 2018 |
| Angelpunzel Limited | Professional & scientific | 2014 |
| Angels Arts & Science Limited | Professional & scientific | 2020 |
| Angris Property Group Ltd | Real estate | 2021 |
| ANN Cropper Limited | Financial services | 2017 |
| Annabella Homes Ltd | Construction | 2025 |
| Anova Capitol Ventures Ltd | Other services | 2013 |
| Anwell Limited | Administrative & support | 2012 |
| Anytime Accounting Limited | Professional & scientific | 2016 |
| AOH Homes Ltd | Real estate | 2020 |
| Apples Marketing Limited | Professional & scientific | 2014 |
| Approved Commercials Ltd | Wholesale & retail | 2023 |
| Approved Transport Ltd | Transport & logistics | 2024 |
| Architectural Planning Studio Ltd | Construction | 2009 |
| Argentium Resources Limited | Wholesale & retail | 2011 |
| ARH Property Limited | Real estate | 2017 |
| Arlaman Property Management Limited | Real estate | 2003 |
| Arlo Projects Ltd | Construction | 2026 |
| Armour Force Ltd | Construction | 2025 |
| Armstle Ltd | Professional & scientific | 2007 |
| Arngrove Real Estate Limited | Real estate | 2024 |
| Arrivl Ltd | Professional & scientific | 2011 |
| Arrow Valves Limited | Manufacturing | 1999 |
| Arrowtechnik Limited | Professional & scientific | 2012 |
| Artap Transport Ltd | Transport & logistics | 2024 |
| Artimino Consulting Limited | Professional & scientific | 2019 |
| Artimino Holdings Limited | Financial services | 2025 |
| Artimino Properties Limited | Real estate | 2025 |
| Artkal Limited | Transport & logistics | 2023 |
| Arundell Property Consultancy Ltd | Professional & scientific | 2024 |
| AS 22 Limited | Professional & scientific | 2024 |
| AS Retail Property Services Limited | Real estate | 2014 |
| Ashby Management Consulting Limited | Information & communication | 2025 |
| Ashlyns Limited | Administrative & support | 2017 |
| Ashlyns Medical Ltd | Health & social care | 2026 |
| Ashridge Advisory Services Limited | Professional & scientific | 2023 |
| Ashridge Capital (ARK) L.P. | | 2010 |
| Ashridge Capital (Phoenix) Limited Partnership | | 2011 |
| Ashridge Capital Fund I GP Limited | Financial services | 2009 |
| Ashridge Capital Fund I LP | | 2009 |
| Ashridge Capital Investments LLP | | 2007 |
| Ashridge CT Limited | Education | 2014 |
| Ashridge Developments (Builders) Limited | Construction | 2001 |
| Ashridge Digital Ltd | Professional & scientific | 2021 |
| Ashridge Educational Services Ltd | Professional & scientific | 2019 |
| Ashridge Executive & Organisation Development Limited | Education | 1984 |
| Ashridge Gate Management Limited | Real estate | 1997 |
| Ashridge Pension Scheme Trustee Limited | Extraterritorial | 2014 |
| Ashridge Retail Limited | Professional & scientific | 2017 |
| Ashridge Services Limited | Professional & scientific | 2022 |
| Ashridge Talent Ltd | Administrative & support | 2020 |
| Ashurst Services Limited | Other services | 2024 |
| Ashworth Aviation Limited | Wholesale & retail | 2021 |
| ASK Property Maintenance & Management Ltd | Households | 2025 |
| Aspect Office Solutions Limited | Wholesale & retail | 2004 |
| Aspen MED Ltd | Health & social care | 2023 |
| Aspery Rowe Limited | Professional & scientific | 2014 |
| Aspier Limited | Wholesale & retail | 2026 |
| ASPIRE2FITNESS Ltd | Extraterritorial | 2017 |
| AST Consultancy Services Limited | Professional & scientific | 2009 |
| Astala Investments Ltd | Real estate | 2022 |
| Astralyn Ltd | Information & communication | 2026 |
| Astro Kitchen Ltd | Hospitality | 2025 |
| Astro's LAB Ltd | Hospitality | 2026 |