| Alive Events Management Ltd | Extraterritorial | 2025 |
| ALL About Property Maintenance Ltd | Construction | 2019 |
| ALL Aspect Waste Management Ltd | Water & waste | 2025 |
| ALL Fabs (Southeast) Limited | Manufacturing | 2011 |
| ALL Systems Security Limited | Administrative & support | 2010 |
| ALL Types Roofing & Guttering Limited | Construction | 2025 |
| Alltech Electrical Services Limited | Construction | 2008 |
| Alltype Building Contractors South East Limited | Construction | 2022 |
| Alltype Roofing Contractors Limited | Construction | 2021 |
| Allytrans Limited | Transport & logistics | 2016 |
| Altered Image Property Consultants Limited | Professional & scientific | 2014 |
| Alton Decorators Limited | Construction | 1973 |
| Altrion Roofing Ltd | Construction | 2025 |
| AM AFO Limited | Construction | 2024 |
| AM Architecture + Design Ltd | Professional & scientific | 2020 |
| AM Steel FAB Ltd | Construction | 2020 |
| Amarok Holdings Limited | Real estate | 2017 |
| Ambony Groundworks Limited | Construction | 2006 |
| Amitha Vishnu Limited | Health & social care | 2022 |
| Amlnia IT Solutions Ltd | Professional & scientific | 2021 |
| Analyticsnova Limited | Wholesale & retail | 2025 |
| Andrei Express Line Ltd | Transport & logistics | 2026 |
| Andrew Day Property Services Ltd | Administrative & support | 2013 |
| Andy Green Property Limited | Households | 2025 |
| Angela Kelly Limited | Extraterritorial | 2014 |
| Animus Developments Limited | Real estate | 2026 |
| Animus Holdings Limited | Financial services | 2026 |
| Annes Gate Property PLC | Administrative & support | 2001 |
| Anno 2017 Joint Holding (UK) Limited | Financial services | 2017 |
| Anomily Ltd | Arts & recreation | 2025 |
| Antique Paper Company Holdings Limited | Financial services | 2022 |
| Antique Paper Company Limited | Wholesale & retail | 2018 |
| Antique Paper Company London Limited | Wholesale & retail | 2020 |
| Antoniop Ltd | Hospitality | 2019 |
| Anyichris Support Services Ltd | Construction | 2020 |
| Aoqdp Ltd | Health & social care | 2025 |
| AP Holdings & Investments Limited | Financial services | 2020 |
| Apostol Construct Ltd | Construction | 2024 |
| Aqua Nexus Property Ltd | Real estate | 2025 |
| Aqua-Clim Contract Services Limited | Manufacturing | 2005 |
| AR7 Services Ltd | Construction | 2024 |
| Arborate Limited | Professional & scientific | 2006 |
| ARC Construction Limited | Construction | 1993 |
| ARC Firepro Ltd | Construction | 2008 |
| Arda-Elwyn Limited | Real estate | 2003 |
| Ardenlea Advisory Limited | Professional & scientific | 2023 |
| Arenix Cover Ltd | Financial services | 2026 |
| Arham Company (BD) Limited | Hospitality | 2026 |
| Arid Capital Limited | Information & communication | 2009 |
| Aris Stone Restoration Ltd | Construction | 2018 |
| Armfield Building Contractors Limited | Construction | 2025 |
| Armour Scaffolding UK Limited | Construction | 2017 |
| Arnold Surfacing Ltd | Construction | 2024 |
| Arps Developments Limited | Construction | 2024 |
| Arundel Smith Investments Limited | Real estate | 2020 |
| Arvag Limited | Construction | 2012 |
| ASA Surveyors Limited | Other services | 2020 |
| Asava Limited | Professional & scientific | 2011 |
| Ashby R&E Ltd | Professional & scientific | 2018 |
| Aspect Enterprises Limited | Construction | 2020 |
| Aspen Property Care Ltd | Administrative & support | 2026 |
| Aspire MS Limited | Administrative & support | 2020 |
| Association of Town Centre Management | Other services | 1993 |
| Assure Core Limited | Wholesale & retail | 2026 |
| Assured END Facilities & Security Limited | Administrative & support | 2015 |
| Astatine Events Limited | Administrative & support | 2011 |
| Astekz Consultancy Limited | Professional & scientific | 2021 |
| Atelier Clothing Ltd | Wholesale & retail | 2025 |
| ATO Hives Limited | Wholesale & retail | 2024 |
| Atyaa Ltd | Information & communication | 2025 |
| Augusta Funding Limited | Administrative & support | 2016 |
| AV Process Limited | Professional & scientific | 2011 |
| AV01 Ltd | Manufacturing | 2016 |
| Avalanchain Ltd | Professional & scientific | 2015 |
| Avi-Scan Limited | Administrative & support | 2002 |
| Aviary Commissioning Management Limited | Professional & scientific | 2023 |
| Avihc Limited | Wholesale & retail | 2020 |
| AWH Group Holdings Limited | Financial services | 2026 |
| Axionique Shop Ltd | Wholesale & retail | 2025 |
| Axis Ductwork Limited | Construction | 2004 |
| Axis Homes Kent Limited | Construction | 2024 |
| Axis Maintenance Limited | Administrative & support | 2019 |
| Aylco Holdings Limited | Financial services | 2022 |
| Aylesbury Vale Parkway Limited | Construction | 2006 |
| AYO Berry Entertainment Ltd | Arts & recreation | 2011 |
| Azagury Fragrance Limited | Wholesale & retail | 2007 |
| B & M Supplies Limited | Wholesale & retail | 2013 |
| B Electrical London Ltd | Manufacturing | 2020 |
| Babybabz Limited | Administrative & support | 2020 |
| Bade Brothers (UK) Ltd | Professional & scientific | 2007 |
| Bailey Lifts Limited | Professional & scientific | 2003 |
| Baker Paving & Building Ltd | Construction | 2022 |
| Bambram Investments LLP | | 2013 |
| Banstead Lift Services Limited | Construction | 2010 |
| Baobei Limited | Manufacturing | 2025 |
| Barry Andrew Property Ltd Limited | Real estate | 2023 |
| Baseline Finishes Ltd | Wholesale & retail | 2018 |
| Bassmore Developments Limited | Construction | 2020 |
| Bat.Taxi Limited | Transport & logistics | 2025 |
| Batch and Co Speciality Coffee Ltd | Hospitality | 2023 |