| ALL PAY Solutions Limited | Administrative & support | 2025 |
| ALL Services in One Ltd | Administrative & support | 2015 |
| ALL SET Digital Solutions Ltd | Professional & scientific | 2026 |
| ALL Type Roofs Ltd | Construction | 2026 |
| ALL Work Limited | Households | 2010 |
| Alladsof Limited | Information & communication | 2023 |
| Alleglobal Ltd | Wholesale & retail | 2025 |
| Allied Care Solutions Ltd | Health & social care | 2022 |
| Allneeds Building and Construction Depot Limited | Wholesale & retail | 2010 |
| Allneeds Group Limited | Wholesale & retail | 2010 |
| Allnet Limited | Extraterritorial | 1965 |
| Ally DE Maurice (UK) Limited | Professional & scientific | 2004 |
| ALM Sports Ltd | Wholesale & retail | 2026 |
| Alma UK International Ltd | Wholesale & retail | 2014 |
| Almeria Cave Ltd | Transport & logistics | 2026 |
| Alora Holdings Ltd | Financial services | 2025 |
| Aloshy's Consulting Ltd | Administrative & support | 2024 |
| ALP Property Maintenance Ltd | Construction | 2019 |
| Alpha Tool Supplies Ltd | Wholesale & retail | 2025 |
| Alquraynigroup Ltd | Real estate | 2024 |
| Alrefai Alternative Medical Services Ltd | Health & social care | 2021 |
| ALS Technical Solutions Limited | Professional & scientific | 2012 |
| Alston Asquith Limited | Professional & scientific | 2018 |
| Alta Tech Ltd | Information & communication | 2025 |
| Alteregobeds Ltd | Manufacturing | 2025 |
| Althamer's Windows Ltd | Construction | 2008 |
| Alwefaq Trading Limited | Construction | 2025 |
| Alymar Ltd | Construction | 2016 |
| Alyn Court RTM Company Limited | Households | 2008 |
| AM Logistic Solutions UK Limited | Transport & logistics | 2013 |
| Amaks Motors Limited | Wholesale & retail | 2013 |
| Amala Consulting Limited | Professional & scientific | 2012 |
| Amazon Computers Limited | Extraterritorial | 1983 |
| Amazon Energy Limited | Extraterritorial | 1980 |
| Amazon Systems Limited | Extraterritorial | 1983 |
| Amens Clothing Limited | Wholesale & retail | 2024 |
| American Top Nails 2 Ltd | Other services | 2023 |
| AMF Marius Electrical and Builder Ltd | Construction | 2019 |
| AMG Vehicle Sales Limited | Administrative & support | 2015 |
| AMG Vehicles Ltd | Other services | 2015 |
| AMK Elite Group Ltd | Financial services | 2025 |
| AMY Thompson Counselling Ltd | Health & social care | 2024 |
| Anabui Foods Limited | Hospitality | 2023 |
| Analopes Care Ltd | Health & social care | 2023 |
| Anand Foot & Ankle Ltd | Health & social care | 2023 |
| Anataras Limited | Wholesale & retail | 2026 |
| Anchor Properties Limited | Real estate | 2000 |
| Ancm Solutions Limited | Other services | 2025 |
| AND Another Ltd | Wholesale & retail | 2023 |
| Andover Car Wash Ltd | Wholesale & retail | 2013 |
| Andreas Symeou LLP | | 2023 |
| Andrew Bloch & Associates Ltd | Professional & scientific | 2020 |
| Andrew Charles Farrier Services Limited | Professional & scientific | 2006 |
| Angel Wings Gifts Ltd | Wholesale & retail | 2019 |
| Angelay V Care Limited | Public administration | 2025 |
| Angle Homes Bassingbourn Limited | Real estate | 2020 |
| Angle Homes Limited | Real estate | 2018 |
| Angle Homes Sawbridgeworth Limited | Extraterritorial | 2020 |
| Angular Properties Ltd | Real estate | 2024 |
| Animark Driving & Logistics Ltd | Transport & logistics | 2019 |
| Anjana's Aesthetics & Laser Ltd | Other services | 2026 |
| Annah Mhishi PVT Limited | Health & social care | 2014 |
| Anointed Property Ltd | Real estate | 2026 |
| Anselhill Academy Limited | Public administration | 2025 |
| Anshraj Limited | Wholesale & retail | 2019 |
| Anthos Florist Ltd | Wholesale & retail | 2005 |
| Antz Delivery Ltd | Construction | 2018 |
| ANY Activity Ltd | Transport & logistics | 2023 |
| ANY Criss Transport Ltd | Transport & logistics | 2017 |
| AOC Consulting Ltd | Professional & scientific | 2025 |
| AOG PSC Limited | Professional & scientific | 2014 |
| AP SD Fifty Five Limited | Wholesale & retail | 2025 |
| Apex Distributors Limited | Wholesale & retail | 2021 |
| Apex Gym Equipment Ltd | Arts & recreation | 2026 |
| APM Plumbing & Heating Services Limited | Construction | 2017 |
| Apollo Gym Wear Limited | Wholesale & retail | 2024 |
| Apporbit Tech Ltd | Information & communication | 2025 |
| APRIL24 Limited | Information & communication | 2024 |
| APS Umbrella Ltd | Administrative & support | 2026 |
| Aqcreaters Limited | Wholesale & retail | 2026 |
| AQR Group Limited | Administrative & support | 2026 |
| Aquila House Ltd | Transport & logistics | 2025 |
| AR Exterior Cleaning Services Ltd | Administrative & support | 2023 |
| AR Health BR Ltd | Financial services | 2022 |
| AR Incentives Limited | Other services | 2025 |
| ARC Angel Health Care Limited | Public administration | 2021 |
| ARC Productions Limited | Information & communication | 2010 |
| Arcadi Verge Limited | Professional & scientific | 2024 |
| Architectural Aluminium Fixing Ltd | Construction | 2008 |
| Archus Communications Ltd | Professional & scientific | 2023 |
| Arenastore Ltd | Wholesale & retail | 2017 |
| Arepraxis Ltd | Education | 2025 |
| Ares K9 Ltd | Administrative & support | 2025 |
| Arewah Creations Limited | Administrative & support | 2021 |
| Argenteus Ventures Limited | Real estate | 2020 |
| Argo FM Ltd | Administrative & support | 2025 |
| Aricorn Limited | Transport & logistics | 2024 |
| Aries VR Limited | Information & communication | 2019 |
| Arika (Freeholds) Ltd | Construction | 2020 |
| Arika (Prestige Flat 3) Ltd | Real estate | 2023 |