| Agewellco Limited | Wholesale & retail | 2025 |
| AGG Fashion Ltd | Wholesale & retail | 2020 |
| Agile Projects Ltd | Professional & scientific | 2011 |
| Agriculture Logistic Investments Limited | Wholesale & retail | 2022 |
| Agrifiniti Ltd | Professional & scientific | 2025 |
| AGS Global Transport Ltd | Transport & logistics | 2023 |
| Agsa Group Limited | Real estate | 2021 |
| AH (WEM) Ltd | Construction | 2026 |
| AH (Whitchurch) Ltd | Construction | 2026 |
| AH GAS Ltd | Construction | 2018 |
| AH North Builder Ltd | Construction | 2019 |
| Ahista Limited | Real estate | 2020 |
| Ahmad Halal Meat Burn Oak Ltd | Wholesale & retail | 2021 |
| AHS Technologies Ltd | Information & communication | 2018 |
| AHZ Medical Ltd | Administrative & support | 2016 |
| AI Analysis Ltd | Information & communication | 2025 |
| AI Sales Services Limited | Information & communication | 2026 |
| Ai-Mglobal Ltd | Administrative & support | 2023 |
| Aibase Ltd | Information & communication | 2011 |
| Aibel Cars Ltd | Wholesale & retail | 2025 |
| Aica Holdings Limited | Financial services | 2026 |
| Aica Investments Limited | Real estate | 2026 |
| Aica Property Limited | Real estate | 2026 |
| AIF Property Investment & Management Limited | Real estate | 2018 |
| AIG Synergy Limited | Wholesale & retail | 2021 |
| Aimable Ltd | Real estate | 2023 |
| Aims Estates Limited | Real estate | 2025 |
| Aineo Ltd | Information & communication | 2025 |
| Air Academy Limited | Education | 2021 |
| Airoya Beauty Ltd | Other services | 2025 |
| Airskyways Limited | Other services | 2021 |
| AIS Property Investments Limited | Real estate | 2019 |
| Aishling Mcloughlin Consultancy Limited | Professional & scientific | 2013 |
| Aivatco Ltd | Administrative & support | 2025 |
| Aiziva Ltd | Wholesale & retail | 2020 |
| AJ Trade Cars Limited | Wholesale & retail | 2015 |
| AJ92 Ventures Ltd | Information & communication | 2023 |
| Ajaks Properties Limited | Construction | 2004 |
| AJB Installations and Repairs Ltd | Construction | 2026 |
| AJH Films Limited | Arts & recreation | 2010 |
| AJP Installations Ltd | Construction | 2007 |
| Ajpc Group Ltd | Professional & scientific | 2002 |
| AJR Props Ltd | Arts & recreation | 2019 |
| AJS Investment Holdings Limited | Financial services | 2026 |
| AJS Props Limited | Arts & recreation | 2012 |
| Ajsp Ltd | Professional & scientific | 2020 |
| AK Auto Xpress Ltd | Wholesale & retail | 2025 |
| AK Smile LAB Ltd | Manufacturing | 2024 |
| AKA Install Ltd | Construction | 2026 |
| Akaar Ltd | Real estate | 2022 |
| Akacons Limited | Other services | 2024 |
| AKG Accounting Ltd | Professional & scientific | 2018 |
| Akhdx LLP | | 2025 |
| AKM Trading Services Ltd | Wholesale & retail | 2009 |
| AKP Aviation Ltd | Administrative & support | 2016 |
| Akshar Business Services Limited | Professional & scientific | 2021 |
| Akshaya Trading Ltd | Hospitality | 2017 |
| AL Chauffeuring Ltd | Transport & logistics | 2024 |
| AL Karam Transport Limited | Transport & logistics | 2016 |
| AL Management Consultancy Ltd | Professional & scientific | 2012 |
| AL Mina Traders Ltd | Wholesale & retail | 2014 |
| Al-Aradi Ltd | Real estate | 2018 |
| Al-Ikhlaseducation Limited | Education | 2019 |
| Al-Saamar Limited | Real estate | 2024 |
| Al-Sayed Private Medical & Medico-Legal Services Ltd | Health & social care | 2020 |
| Alain Media Ltd | Wholesale & retail | 2025 |
| Alan Cook Travel Service Limited | Administrative & support | 1981 |
| ALB Affordable Contractors Ltd | Construction | 2021 |
| ALB Homes Estates Ltd | Real estate | 2024 |
| ALB Homes Ltd | Construction | 2015 |
| ALB Improvements Ltd | Construction | 2019 |
| ALB Vision Construction Ltd | Construction | 2024 |
| Albanwise Synergy Consultancy Limited | Real estate | 2025 |
| Albategnius Quantitative Solutions Ltd | Professional & scientific | 2022 |
| Albcorp Limited | Financial services | 2024 |
| Albert House Investments Ltd | Real estate | 2018 |
| Albert Park Ltd | Real estate | 2020 |
| Albpro Cleaning Services Ltd | Administrative & support | 2024 |
| Albra Services Ltd | Transport & logistics | 2018 |
| Alchemist DB Limited | Professional & scientific | 2016 |
| Alco & Sons Limited | Hospitality | 2019 |
| Aldel Designs Limited | Other services | 2017 |
| Aldenham Country Park Trust Limited | Other services | 2011 |
| Aldenham Manor Estate Management (NO 1) Limited | Households | 1996 |
| Aldenham Renaissance Community Interest Company | Agriculture & fishing | 2011 |
| Aldermen Court (N11) RTM Company Limited | Households | 2019 |
| Aldridge Fleet Consultants Ltd | Administrative & support | 2022 |
| ALE Architectural Ltd | Construction | 2017 |
| ALE Inns Limited | Hospitality | 2012 |
| Alert Care Services UK Ltd | Extraterritorial | 2014 |
| Alex Elite Groundworks Ltd | Construction | 2025 |
| Alexander Personal Management Limited | Administrative & support | 1997 |
| Alexander Ragnar Limited | Professional & scientific | 2023 |
| Alexandra Anthony Limited | Professional & scientific | 2004 |
| Alexandra Muntianu Limited | Health & social care | 2021 |
| Alford Letting Company Limited | Real estate | 2014 |
| ALG Watford Ltd | Construction | 2021 |
| Algarve Pro Racing LLP | | 2021 |
| Algorial Limited | Wholesale & retail | 2016 |
| ALI G Limited | Professional & scientific | 2000 |