| Adhd PUB Co Limited | Hospitality | 2018 |
| Adis Courier Ltd | Transport & logistics | 2018 |
| Adiuvara Limited | Financial services | 2018 |
| ADJ Events Ltd | Arts & recreation | 2016 |
| Adjoavi Lifestyle Ltd | Wholesale & retail | 2024 |
| ADL Construct Ltd | Construction | 2025 |
| Adlchouses Ltd | Real estate | 2026 |
| Admiral MC Ltd | Wholesale & retail | 2020 |
| Admon 911 Limited | Construction | 2011 |
| ADN Installations Limited | Construction | 2012 |
| Adrian Forster Limited | Wholesale & retail | 2003 |
| Advanced Bioprocess Services Limited | Professional & scientific | 2016 |
| Advanced Technical Services Ltd | Construction | 2012 |
| Advancia Retail Displays Limited | Construction | 2015 |
| Advantica Intellectual Property Limited | Administrative & support | 1992 |
| Advent (Leicester) Limited | Professional & scientific | 2009 |
| AEH Auditing Limited | Professional & scientific | 2025 |
| Aeons & Eras Ltd | Education | 2023 |
| Aeroshi Ltd | Information & communication | 2025 |
| Aesthetic Revival Limited | Health & social care | 2020 |
| Aesthetics by Charlottex Ltd | Other services | 2024 |
| AET Training Ltd | Education | 2024 |
| Afax Properties Ltd | Real estate | 2024 |
| AFC Quantity Surveying Services Limited | Professional & scientific | 2013 |
| Affixxius Limited | Information & communication | 2021 |
| Affordable Tree Services Ltd | Agriculture & fishing | 2011 |
| Afmgmt Limited | Professional & scientific | 2023 |
| Afri Global Limited | Professional & scientific | 2023 |
| AG Cars Loughborough Ltd | Wholesale & retail | 2022 |
| AG Logistic Services Limited | Transport & logistics | 2019 |
| Agar Hygiene Limited | Administrative & support | 2002 |
| Agaricus Property Limited | Real estate | 2022 |
| Agas Enterprise Ltd | Hospitality | 2022 |
| Agbasocinematics Ltd | Professional & scientific | 2025 |
| Aggressive Civvies Ltd | Wholesale & retail | 2025 |
| Agility and More Academy Ltd | Arts & recreation | 2024 |
| Agon Events Ltd | Arts & recreation | 2024 |
| AGP Civil Engineering Ltd | Construction | 2014 |
| Agri-Seeds (UK) Limited | Agriculture & fishing | 2001 |
| Agricultural Independent Marketing Limited | Agriculture & fishing | 2000 |
| Agronomy Training Ltd | Agriculture & fishing | 2023 |
| Agrova UK Holdings Limited | Financial services | 2025 |
| Agsw Limited | Wholesale & retail | 2023 |
| AH & RB Holdings Limited | Manufacturing | 2010 |
| AH (East HAM) Limited | Administrative & support | 2019 |
| AH (East Kilbride) Limited | Administrative & support | 2019 |
| AH (Kenyon) Ltd | Administrative & support | 2019 |
| AH (Rawyards) Limited | Administrative & support | 2019 |
| AH (Westmoreland) Limited | Administrative & support | 2019 |
| Ahad and Kabir Co Limited | Real estate | 2025 |
| Ahoma Trading Ltd | Wholesale & retail | 2025 |
| AI Bell Ltd | Information & communication | 2021 |
| AI Global Education Limited | Information & communication | 2023 |
| AI Idea Factory Ltd | Information & communication | 2019 |
| AI Infra Ltd | Information & communication | 2026 |
| Aimee Henri Intimates Ltd | Professional & scientific | 2022 |
| Air Movement Systems Ltd | Professional & scientific | 2006 |
| Air Plasma Limited | Manufacturing | 2010 |
| Air Technology Energy Limited | Professional & scientific | 1999 |
| Air Technology Limited | Professional & scientific | 1987 |
| Air Tools & Compressors Limited | Manufacturing | 1984 |
| AIR400 Ltd | Arts & recreation | 2026 |
| Airreale Ltd | Manufacturing | 2025 |
| Aivion Technology Ltd | Wholesale & retail | 2026 |
| Aiyp Ltd | Construction | 2025 |
| AJ Motors (Midlands) Ltd | Wholesale & retail | 2022 |
| Aj's Coffee House Ltd | Hospitality | 2026 |
| AJOB4JOHN Limited | Other services | 2023 |
| AJS Commercial Repairs Ltd | Wholesale & retail | 2024 |
| AKA Investment Group Ltd | Real estate | 2025 |
| Akea Private Limited | Other services | 2022 |
| Akilea Ltd | Manufacturing | 2021 |
| Aks&D Holdings Ltd | Real estate | 2025 |
| AL Manaar Academy Limited | Education | 2024 |
| Alan March Sport Limited | Arts & recreation | 2012 |
| Alan Staley Building Contractors Ltd | Construction | 2014 |
| Alba Financial Accountants Limited | Professional & scientific | 2008 |
| Albany Mortgage Solutions Limited | Financial services | 2007 |
| Albatross Healthcare Ltd | Administrative & support | 2020 |
| Albenex Ltd | Financial services | 2023 |
| Albert Trans Ltd | Transport & logistics | 2013 |
| Albion Tiling Limited | Construction | 2000 |
| Albo Properties Limited | Construction | 2017 |
| ALC Interior Design Limited | Construction | 2003 |
| Alca Trans Ltd | Transport & logistics | 2025 |
| Alchemis Solutions Limited | Information & communication | 2009 |
| Alchemyx Ltd | Information & communication | 2024 |
| Alcuris Ltd | Professional & scientific | 2015 |
| Aldridge Independent Services Limited | Administrative & support | 2020 |
| Aldrin Bidco Limited | Financial services | 2020 |
| Aldrin Holdings Limited | Financial services | 2020 |
| Aldrin Mid-Holdings Limited | Financial services | 2020 |
| Aldrin Midco Limited | Professional & scientific | 2020 |
| Aldrin Sub-Holdings Limited | Financial services | 2020 |
| Aldrin Topco Limited | Professional & scientific | 2020 |
| Aldwold Limited | Professional & scientific | 2019 |
| Aled Rhys Consultancy Limited | Extraterritorial | 2019 |
| Alert IT Consulting Ltd | Information & communication | 2014 |
| Alert Property Limited | Real estate | 2021 |
| Alert Ventures Limited | Wholesale & retail | 2023 |