| Access Recruitment & Training Limited | Administrative & support | 2022 |
| Accio Depulso Limited | Professional & scientific | 2024 |
| Accounting & Finance Solutions Limited | Professional & scientific | 2017 |
| Accucheck Ltd | Health & social care | 2023 |
| Accurasync Limited | Professional & scientific | 2023 |
| Accurise Ltd | Information & communication | 2019 |
| Accuro Transcription Solutions Limited | Information & communication | 2010 |
| Ace 7 Solutions Limited | Information & communication | 2023 |
| Ace Consult Accountants Ltd | Professional & scientific | 2021 |
| Ace Global Consulting Limited | Professional & scientific | 2026 |
| Ace Haircuts Ltd | Other services | 2024 |
| Ace Living Property Solutions Ltd | Real estate | 2021 |
| Ace Testing Services Limited | Administrative & support | 2023 |
| Aced Housing Ltd | Real estate | 2024 |
| ACEIT247.COM Limited | Information & communication | 2024 |
| Aces Sameday Couriers Limited | Transport & logistics | 2005 |
| Acetechuk CIC | Health & social care | 2024 |
| ACH RST Limited | Professional & scientific | 2022 |
| Acheson & Acheson Limited | Manufacturing | 1992 |
| Achieve Accounting Limited | Professional & scientific | 2020 |
| Achieve and Learn Trust | Education | 2012 |
| Achieve Goal 12 Ltd | Professional & scientific | 2019 |
| Achilles JJB Company Limited | Real estate | 2020 |
| Achr Consulting Limited | Professional & scientific | 2024 |
| ACL (AR) Ltd | Administrative & support | 2020 |
| Aclg Consulting Management Limited | Professional & scientific | 2012 |
| Acloud Tech Ltd | Information & communication | 2022 |
| ACO Developments Ltd | Construction | 2023 |
| Acorn Delivery Services Limited | Professional & scientific | 2022 |
| Acousfit Ltd | Construction | 2023 |
| ACR Garden Services Limited | Administrative & support | 2003 |
| Acres Consulting Ltd | Professional & scientific | 1994 |
| Acron Aviation Academy UK Limited | Financial services | 2015 |
| Acron Aviation Analytics Limited | Transport & logistics | 2000 |
| Acron Aviation Group Limited | Financial services | 2021 |
| Acron Aviation Holdings Limited | Financial services | 2020 |
| Acron Aviation Limited | Financial services | 2020 |
| Acron Aviation Training Solutions Limited | Manufacturing | 2006 |
| Acrophile Ltd | Real estate | 2009 |
| Across the Board Limited | Administrative & support | 2003 |
| Acsciens Limited | Professional & scientific | 2025 |
| ACT Lean Ltd. | Professional & scientific | 2011 |
| Actaeon Solutions Group Ltd | Construction | 2015 |
| Action Pest Control Limited | Administrative & support | 1994 |
| Activecore Limited | Information & communication | 2021 |
| Actupnorth Limited | Information & communication | 2012 |
| Actve Limited | Professional & scientific | 2024 |
| Aculinq Limited | Information & communication | 2025 |
| Aculore Statistics Ltd | Information & communication | 2016 |
| ACW Property Holdings Limited | Real estate | 2022 |
| AD Global Logistics Limited | Transport & logistics | 1998 |
| AD42 Limited | Administrative & support | 2015 |
| Adacar Ltd | Wholesale & retail | 2012 |
| Adam Bates Ltd | Professional & scientific | 2016 |
| Adam Lang Limited | Professional & scientific | 2024 |
| Adam Stamp Limited | Professional & scientific | 2006 |
| Adams Accounting Limited | Professional & scientific | 1999 |
| Adams Building Consultants Ltd | Construction | 2005 |
| Adams Cakes Limited | Manufacturing | 2019 |
| Adamschofieldpt Limited | Arts & recreation | 2018 |
| Adaptive Custodial Services Ltd | Financial services | 2026 |
| ADB Management Limited | Professional & scientific | 2026 |
| Adco Rail Limited | Professional & scientific | 2021 |
| ADD Plant Services Ltd | Construction | 2023 |
| Addah Chauffeurs Ltd | Transport & logistics | 2023 |
| Addded Limited | Information & communication | 2019 |
| Addison Lewis Property Group Ltd | Real estate | 2022 |
| Adel Gardens Management Company Ltd | Real estate | 2022 |
| Adelphi Street Ltd | Construction | 2014 |
| Adelphi Village Management Company Limited | Real estate | 2008 |
| Adelphi Wharf Management Ltd | Real estate | 2015 |
| Adelphi Wharf Phase 1 Ltd | Administrative & support | 2017 |
| Adeptio Consulting Limited | Administrative & support | 2011 |
| Adepts Group Limited | Professional & scientific | 2021 |
| Adgiliti Digital Services Ltd | Information & communication | 2020 |
| Adhesives & Sealants Limited | Manufacturing | 2002 |
| Adiosc Consulting Limited | Professional & scientific | 2015 |
| Adiso Therapeutics Limited | Professional & scientific | 2021 |
| ADL Holdco Limited | Financial services | 2024 |
| Adlington Place Management Company Limited | Households | 2001 |
| Adlington Property Limited | Real estate | 2016 |
| Adlington Road Limited | Construction | 2024 |
| Adlington Welding Supplies (Holdings) Limited | Financial services | 2013 |
| ADM Property Services Limited | Construction | 2017 |
| Admiral Sports Limited | Wholesale & retail | 2001 |
| Admiral Sportswear Limited | Wholesale & retail | 2010 |
| Admiral Teamsports Limited | Wholesale & retail | 2014 |
| Admissible Systems Ltd | Information & communication | 2026 |
| Admove Ltd | Real estate | 2015 |
| Adnos Solutien Limited | Professional & scientific | 2026 |
| Adora Property Ltd | Real estate | 2020 |
| Adores Properties Limited | Real estate | 2021 |
| Adria Dental Limited | Health & social care | 2024 |
| Adrian & Co Property Limited | Real estate | 2018 |
| Adrian Borton Services Ltd | Professional & scientific | 2019 |
| Adrian Francis Associates Ltd | Energy | 2002 |
| Adrian Rowley Consultancy Limited | Professional & scientific | 2016 |
| Adrian TAN Holding Ltd | Financial services | 2026 |
| Adrian TAN Property Ltd | Real estate | 2026 |
| Adthion Limited | Professional & scientific | 2023 |