| AMX Healthtech UK Limited | Manufacturing | 2026 |
| Amyk Logistics Limited | Transport & logistics | 2026 |
| AN Construction Ltd | Construction | 2020 |
| Anaa Group Limited | Wholesale & retail | 2025 |
| Anaesthesia & Critical Care Limited | Health & social care | 2011 |
| Anaesthetics Ltd | Health & social care | 2010 |
| Analysis People Ltd | Other services | 2017 |
| Analytico Holdings Limited | Financial services | 2021 |
| Analytico Limited | Professional & scientific | 2018 |
| Analytics Consulting Holdings Limited | Financial services | 2022 |
| Analytiq Global Ltd | Information & communication | 2024 |
| Anamac Enterprises Limited | Wholesale & retail | 2021 |
| Anamya Limited | Professional & scientific | 2010 |
| Anavrin Beauty Ltd | Other services | 2014 |
| Anayas Collection Ltd | Wholesale & retail | 2023 |
| Anbe Sivam Ltd | Wholesale & retail | 2026 |
| AND Dream of Sheep Ltd | Real estate | 2021 |
| Andre Upholstery Limited | Other services | 2014 |
| Andreev Services Ltd | Wholesale & retail | 2007 |
| Andrew Blackburn Consulting Ltd | Professional & scientific | 2019 |
| Andrew Potter Consulting Limited | Construction | 2011 |
| Andrien Meyers Rodrigues Limited | Professional & scientific | 2017 |
| Andromeda Technologies Limited | Information & communication | 2023 |
| Andy Da-Silva Security Services Limited | Administrative & support | 2017 |
| Andy Strings Ltd | Wholesale & retail | 2021 |
| Angel Advisory Ltd | Professional & scientific | 2026 |
| Angel Care Enterprise Ltd | Real estate | 2023 |
| Angel Property 1 Limited | Real estate | 2024 |
| Angela Morris Limited | Other services | 2018 |
| Angleco Solutions Limited | Real estate | 2025 |
| Anglo American System Consultants Limited | Professional & scientific | 2001 |
| Anglo Chinese Cultural & Sports Exchange Association | Other services | 2016 |
| Anglo-Chinese Medicine Doctor Society | Other services | 2004 |
| Anglocypria Limited | Real estate | 2003 |
| Anha Medics Ltd | Health & social care | 2021 |
| Anha Properties Ltd | Real estate | 2025 |
| Anita Ryan Ltd | Professional & scientific | 2015 |
| Aniya Property Ltd | Real estate | 2025 |
| Anjana Tech Ltd | Information & communication | 2023 |
| Anjoleri Services Limited | Professional & scientific | 2024 |
| Annapurna Properties Ltd | Real estate | 2025 |
| Annexis Health Ltd | Information & communication | 2024 |
| Annliz Properties Ltd | Real estate | 2025 |
| Anohs Holding Ltd | Financial services | 2021 |
| Another Music Festival Ltd | Arts & recreation | 2024 |
| Anpr Enforcement Ltd | Administrative & support | 2014 |
| Ansh Properties Ltd | Real estate | 2023 |
| Ansible Global Limited | Administrative & support | 2025 |
| Ansio Ltd | Wholesale & retail | 2014 |
| Ansra Ltd | Information & communication | 2022 |
| Antd Ltd | Real estate | 2019 |
| Anthromod Ltd | Professional & scientific | 2011 |
| Antonino's Pizza Events Ltd | Hospitality | 2022 |
| Anuciya Constructions Ltd | Construction | 2016 |
| Anuja Properties Ltd | Real estate | 2020 |
| ANY Trades Ltd | Information & communication | 2024 |
| Anytimework Ltd | Health & social care | 2024 |
| AOA Medicals and Consultants Limited | Health & social care | 2025 |
| Aocs Property Maintenance Ltd | Construction | 2011 |
| AOM Consulting Services Limited | Manufacturing | 2024 |
| Apah Property Ltd | Real estate | 2024 |
| APD Consult Ltd | Professional & scientific | 2014 |
| Apego Ltd | Professional & scientific | 2024 |
| Apercu (International) Limited | Other services | 2012 |
| Apertours Property Marketing Limited | Professional & scientific | 2024 |
| Apex Chemical Technologies Ltd | Manufacturing | 2021 |
| Apex Consortium Ltd | Financial services | 2015 |
| APEX26 Consulting Limited | Administrative & support | 2021 |
| Apicallity Limited | Professional & scientific | 2015 |
| Apicius Food Services Ltd | Hospitality | 2017 |
| APK Medicolegal Ltd | Health & social care | 2026 |
| Apollo Corporation Limited | Wholesale & retail | 2024 |
| Apollo MIS Ltd | Information & communication | 2011 |
| Apostrophe Solutions Limited | Professional & scientific | 2007 |
| Apple Services Ltd | Administrative & support | 2026 |
| Appliance Breakdown UK Ltd | Other services | 2020 |
| Appliances Engineering Ltd | Wholesale & retail | 2023 |
| Apps Properties Ltd | Real estate | 2024 |
| Apricot Learning Limited | Education | 2006 |
| APS Construction Ltd | Construction | 2015 |
| APS Homes Limited | Construction | 2020 |
| Aptiga Limited | Administrative & support | 2009 |
| Apug Investmments Ltd | Wholesale & retail | 2022 |
| AQ Cardiology Ltd | Professional & scientific | 2023 |
| Aqua-Steam Generators Ltd | Administrative & support | 2009 |
| Aquarium Connections Ltd | Agriculture & fishing | 2014 |
| AR Dermatology Limited | Health & social care | 2024 |
| AR Spaces Ltd | Wholesale & retail | 2025 |
| Araash Logistics UK Ltd | Transport & logistics | 2022 |
| Arabotic Limited | Transport & logistics | 2009 |
| Aragon Management Company (Sutton) Limited | Households | 1987 |
| Aram Inc. Ltd. | Professional & scientific | 2017 |
| Aran Diez Consulting Ltd | Professional & scientific | 1992 |
| Aranstruct Ltd | Construction | 2024 |
| Aras Engineering Limited | Construction | 2023 |
| Aratus Ltd | Information & communication | 2022 |
| Arawak Plumbing Ltd | Construction | 2022 |
| Arbavasile Limited | Transport & logistics | 2024 |
| Arc:Mc Holdings Limited | Financial services | 2011 |
| Arc:Mc Limited | Professional & scientific | 2009 |