| Alpha Welding & Steel Fabrications Ltd | Manufacturing | 2015 |
| Alphalink Legal Services Ltd | Professional & scientific | 2020 |
| Alphastream.Io Ltd | Information & communication | 2015 |
| ALPI38 Limited | Hospitality | 2024 |
| Alsim Consulting Limited | Information & communication | 2023 |
| Altairminds Technologies Ltd | Information & communication | 2025 |
| Alternative Options Care Limited | Health & social care | 2023 |
| Alternative Options Limited | Construction | 2023 |
| Altitude Prime Limited Partnership | | 2016 |
| Altrad Holdings Ltd | Construction | 2018 |
| Aluminium Solutions Limited | Manufacturing | 2014 |
| Alusystem-Uk Ltd | Manufacturing | 2025 |
| Alwoodley Partners Limited | Professional & scientific | 2013 |
| AM Campos Constructions Ltd | Construction | 2025 |
| AMA Build Services Limited | Professional & scientific | 2023 |
| AMA Living Ltd | Real estate | 2025 |
| Amable Homes Limited | Real estate | 2021 |
| Amanah Youth Club CIC | Education | 2025 |
| Amanda Bell CA Professional Services Limited | Administrative & support | 2016 |
| Amariah Care Consultancy Ltd | Professional & scientific | 2025 |
| Amat Developments (Kent) Limited | Construction | 2026 |
| Amath Consulting Ltd | Information & communication | 2013 |
| Amavic Limited | Professional & scientific | 2022 |
| Amazin Care Limited | Health & social care | 2013 |
| Amazing Animals Ltd. | Professional & scientific | 2001 |
| Amazing Grace Heritage Limited | Health & social care | 2015 |
| Amazing Hair & Beauty Limited | Other services | 2013 |
| Ambassador Services Group Limited | Financial services | 2024 |
| Ambassador Services Limited | Administrative & support | 1985 |
| Amber Holdings 2022 Limited | Real estate | 2022 |
| Amber's Vintage Ltd | Hospitality | 2018 |
| Amberley Property Services Limited | Real estate | 1997 |
| Ambr Lets Limited | Real estate | 2026 |
| Amcor Group International Ltd | Administrative & support | 2026 |
| AMD Environmental (North) Limited | Construction | 2021 |
| AMD Environmental Limited | Construction | 1989 |
| AMD FM Limited | Administrative & support | 2018 |
| AMD Group Holdings Limited | Financial services | 2019 |
| AME Properties and Projects Developments Ltd. | Construction | 2018 |
| Ameerah Care Services Limited | Health & social care | 2015 |
| Amelia Rose Beauty Limited | Other services | 2024 |
| AMF Ceiling & Interior Ltd | Construction | 2020 |
| AMG Portfolio Limited | Real estate | 2026 |
| AMI Property Management Limited | Real estate | 2024 |
| Amile London Ltd | Wholesale & retail | 2024 |
| Amir London Limited | Arts & recreation | 2015 |
| Amiron Electrical Ltd | Construction | 2025 |
| Amitt Consulting Limited | Financial services | 2016 |
| Amity Support Limited | Health & social care | 2023 |
| AML Trans Ltd | Transport & logistics | 2026 |
| Ammcass Construction Engineering Group Limited | Construction | 2016 |
| Ammcass Construction Engineering International Limited | Construction | 2024 |
| Ammonite Dental LAB Limited | Health & social care | 2026 |
| Amok Digital UK Limited | Professional & scientific | 2022 |
| AMP Property Services Ltd | Construction | 2019 |
| AMP Trans-Tir Ltd | Transport & logistics | 2026 |
| Ample Energy Services Limited | Construction | 2005 |
| Ampocc Solutions Limited | Public administration | 2016 |
| Amry Ltd | Information & communication | 2015 |
| Amtico LVT Ltd | Wholesale & retail | 2025 |
| Amtrax Limited | Professional & scientific | 1996 |
| AMY Pizza Ltd | Hospitality | 2024 |
| AN Classic Wine Ltd | Wholesale & retail | 2019 |
| ANA & Diana Ltd | Administrative & support | 2024 |
| Analytic Synergy Solutions Limited | Professional & scientific | 2012 |
| Anastania Limited | Construction | 2022 |
| Anaz Ltd | Health & social care | 2022 |
| ANB Property Services Ltd | Real estate | 2019 |
| Anb-Bog Ltd | Transport & logistics | 2024 |
| Anca & John Services Limited | Transport & logistics | 2015 |
| Anchor Bay Heritage Ltd | Manufacturing | 2024 |
| Anchorite Limited | Administrative & support | 2025 |
| AND London (Leasing) Limited | Administrative & support | 2021 |
| Andalec Consulting Limited | Information & communication | 2005 |
| Ander Ltd | Other services | 2020 |
| Andrea Weddings and Events Ltd | Administrative & support | 2024 |
| Andreas Catering Limited | Hospitality | 2013 |
| Andrew Sissons Consulting (London) Limited | Real estate | 2013 |
| Andrius Rekstys Ltd | Construction | 2015 |
| Andy Loads Ltd | Transport & logistics | 2005 |
| Angel Dreams Events Ltd | Hospitality | 2023 |
| Angela & Nenad Ltd. | Construction | 2012 |
| Angiza CIC | Education | 2024 |
| Anglian Energy Sales & Development Limited | Professional & scientific | 2011 |
| Anibaeli Ltd | Wholesale & retail | 2025 |
| Anika Mall Ltd | Wholesale & retail | 2023 |
| Anima Residential Care Limited | Health & social care | 2023 |
| Anlive Co. Ltd | Real estate | 2021 |
| Anna Jahn Ltd | Professional & scientific | 2014 |
| Annabestcare Limited | Public administration | 2023 |
| Annams Sarees Ltd | Wholesale & retail | 2020 |
| Annapoorna Hospitality Limited | Hospitality | 2024 |
| Annarose Property Solutions Limited | Professional & scientific | 2019 |
| Annavm Ltd | Transport & logistics | 2024 |
| Anointed Arms Care Limited | Health & social care | 2025 |
| Another Home Limited | Real estate | 2017 |
| ANP Building Services Limited | Construction | 2011 |
| Anpr Enforcer Ltd | Financial services | 2018 |
| ANR France Ltd | Real estate | 2018 |
| Ansari's Kitchen Limited | Hospitality | 2023 |