| Artemis Ktiniatriki Limited | Professional & scientific | 2017 |
| Artha Group Ltd | Wholesale & retail | 2025 |
| Arthur Best Consulting Engineers Limited | Professional & scientific | 2017 |
| Artisan Apps Limited | Information & communication | 2024 |
| Artsystem Construction Ltd. | Construction | 2018 |
| ARV Commercial Investments Ltd | Real estate | 2014 |
| ARV Holdings Limited | Financial services | 2020 |
| Arvee International UK Ltd | Wholesale & retail | 2023 |
| Arya Bedrooms Limited | Manufacturing | 2018 |
| Arya Homeware Ltd | Wholesale & retail | 2023 |
| ARZ Private Hire Ltd | Transport & logistics | 2025 |
| AS Crown Builder Limited | Construction | 2024 |
| AS Retail Trading Limited | Wholesale & retail | 2020 |
| AS1 Healthcare Ltd | Health & social care | 2026 |
| ASA Patel Property Limited | Real estate | 2023 |
| Asad Enterprises Limited | Professional & scientific | 2025 |
| Asap Swift Logistics Limited | Transport & logistics | 2024 |
| Asap Systems Limited | Information & communication | 2010 |
| ASB Distro Ltd | Wholesale & retail | 2019 |
| Ascend Training Consultancy Ltd | Education | 2025 |
| Ascenda Ventures Ltd | Real estate | 2025 |
| Ascent Training Limited | Education | 2012 |
| Asees Off-Licence Limited | Wholesale & retail | 2024 |
| Asgb Works Limited | Construction | 2019 |
| ASH Auto Limited | Wholesale & retail | 2016 |
| ASH Tech Ltd | Transport & logistics | 2025 |
| ASHA360 Limited | Administrative & support | 2025 |
| Ashdekk Limited | Real estate | 2025 |
| Ashford Car Radio Limited | Transport & logistics | 1978 |
| Ashford Manor Services Limited | Professional & scientific | 2012 |
| Ashford Property Investments Limited | Real estate | 2012 |
| Ashiah Ltd | Health & social care | 2018 |
| Ashley's Removals Ltd | Transport & logistics | 2025 |
| Ashmore Court Residents' Association Limited | Households | 1972 |
| ASK PVT Ltd | Real estate | 2026 |
| Asmaa Enterprises Limited | Wholesale & retail | 1997 |
| Asoare Ltd | Wholesale & retail | 2025 |
| Asociacion Mira Reino Unido Ltd | Health & social care | 2012 |
| ASP Informations Ltd | Construction | 2025 |
| Aspire Surveys Ltd | Construction | 2019 |
| ASR London Limited | Transport & logistics | 2015 |
| Asra Limited | Information & communication | 2024 |
| Assembleia DE Deus Vida Nova Limited | Other services | 2012 |
| Assured Build and Design Ltd | Construction | 2025 |
| Assured Building Services Ltd | Construction | 2023 |
| Assured Financing Ltd | Financial services | 2025 |
| Aston Hair Ltd | Other services | 2025 |
| Astravue Limited | Wholesale & retail | 2025 |
| Astryn Ember Ltd | Wholesale & retail | 2025 |
| Asya 2016 Ltd | Other services | 2016 |
| ATA76 Limited | Administrative & support | 2017 |
| Atawa UK Limited | Administrative & support | 2021 |
| Athletes Performance & Excellence Company Limited | Education | 2018 |
| Athluex Life Ltd | Wholesale & retail | 2024 |
| Atlas Joinery Ltd | Construction | 2018 |
| Atmaa Limited | Wholesale & retail | 2025 |
| Atme Transport Ltd | Transport & logistics | 2025 |
| Atoz Property Box Limited | Real estate | 2025 |
| Atrium Hotel Limited | Hospitality | 2017 |
| Attica Group Ltd | Transport & logistics | 2024 |
| AU Trader Ltd | Wholesale & retail | 2015 |
| Au-Dela Hair Ltd | Other services | 2024 |
| Aucm Limited | Arts & recreation | 2017 |
| Aunt Omo's Kitchen & Catering Services Ltd | Hospitality | 2024 |
| Aura Capital Limited | Real estate | 2018 |
| Aurora Brothers Limited | Real estate | 1995 |
| Aurora Luxury London Limited | Manufacturing | 2025 |
| Aurora Studio by Thav Ltd | Professional & scientific | 2024 |
| AURORAGROUP2025 Limited | Transport & logistics | 2025 |
| Auspicious Sales Ltd | Wholesale & retail | 2016 |
| Auto Excell Ltd | Wholesale & retail | 2021 |
| Auto Mama Ltd | Wholesale & retail | 2017 |
| Autobridge Limited | Wholesale & retail | 2019 |
| Autoccart Limited | Wholesale & retail | 2019 |
| Autodrive Hanworth Limited | Wholesale & retail | 2024 |
| Auzu Limited | Wholesale & retail | 2020 |
| AV Beauty Passion Ltd | Other services | 2019 |
| AV Designs Kitchen and Bedrooms Ltd | Manufacturing | 2025 |
| AV Spectrum Limited | Professional & scientific | 2012 |
| Avansys IT Limited | Information & communication | 2020 |
| Avantech Engineering Limited | Professional & scientific | 2022 |
| Avaton Group Ltd | Transport & logistics | 2018 |
| Avex Aviation Express Ltd | Transport & logistics | 2016 |
| Avia Cargo Services Limited | Transport & logistics | 2005 |
| Aviewfromabove Ltd | Professional & scientific | 2026 |
| Avishay IT Solutions Ltd | Information & communication | 2022 |
| Aviyam Limited | Real estate | 2026 |
| AVR Mart Ltd | Wholesale & retail | 2018 |
| Avra Property Services Ltd | Construction | 2024 |
| AVS (London) Limited | Extraterritorial | 2016 |
| AVS Group Services Ltd | Wholesale & retail | 2020 |
| Avyan Property Group Ltd | Real estate | 2024 |
| Awadh Trading Ltd | Wholesale & retail | 2020 |
| Awanza Car Club Ltd | Wholesale & retail | 2023 |
| AWM Consultancy Ltd | Professional & scientific | 2022 |
| AWM Group Holdings Ltd | Financial services | 2024 |
| AWO Haven Ltd | Health & social care | 2025 |
| Awsbil Ltd | Wholesale & retail | 2024 |
| Awsre Ltd | Information & communication | 2019 |
| Axis Transport Limited | Transport & logistics | 2025 |