| Arksigma Ltd | Information & communication | 2020 |
| Armaan Gill Properties Ltd | Real estate | 2025 |
| Armeco Limited | Information & communication | 2025 |
| Armi (Kent) Limited | Hospitality | 2017 |
| Arnulf Limited | Health & social care | 2007 |
| Arora Design Consultancy Ltd | Professional & scientific | 2018 |
| Aroz Ltd | Real estate | 2026 |
| Arpthetrainingzone Ltd | Arts & recreation | 2026 |
| Arran Court (Purley) Ltd | Health & social care | 1994 |
| Array Minds Limited | Information & communication | 2022 |
| Arrow Capital Management Ltd | Financial services | 2025 |
| Art Accounting Services Limited | Professional & scientific | 2021 |
| Art Daka Ltd | Manufacturing | 2022 |
| Artad Property Limited | Real estate | 2024 |
| Artonco Ltd | Wholesale & retail | 2021 |
| Arvscom Limited | Information & communication | 2005 |
| Arya Estates (Holding) Limited | Real estate | 2026 |
| Arya Estates Ltd | Real estate | 2022 |
| AS Fit AS Limited | Extraterritorial | 2021 |
| AS Seen by Ravi Ltd | Real estate | 2021 |
| Asag Limited | Hospitality | 2025 |
| Ascent Assets Limited | Financial services | 1998 |
| Asfand Enterprises Ltd | Real estate | 2024 |
| Asher Glean Limited | Arts & recreation | 2024 |
| Ashford Cleaning Group Ltd | Administrative & support | 2026 |
| Ashforde Group Limited | Construction | 2025 |
| Asim Qureshi Ltd | Construction | 2018 |
| ASL Properties Limited | Hospitality | 2013 |
| Asmin Textile Ltd | Wholesale & retail | 2021 |
| ASR Business Solutions Ltd | Professional & scientific | 2018 |
| Asset Vault Competitions Ltd | Arts & recreation | 2025 |
| Assiduous Brooms Cleaning Services Ltd | Administrative & support | 2019 |
| Assist Bookkeeping Services Ltd | Professional & scientific | 2014 |
| Assist Consulting Limited | Professional & scientific | 2012 |
| Assistify Autonomous Ltd | Manufacturing | 2026 |
| Association of Ayurvedic Professionals UK | Health & social care | 2017 |
| Assure Scaffolding Limited | Construction | 2012 |
| Assured Services Limited | Hospitality | 1994 |
| Assuretax Accountants Ltd | Professional & scientific | 2010 |
| Astoria Court Management Limited | Administrative & support | 2001 |
| Astria Developments Limited | Construction | 2014 |
| ATL TAN Properties Limited | Real estate | 2023 |
| Atlas Pandi UK Ltd | Transport & logistics | 2023 |
| Atoshi George Limited | Professional & scientific | 2026 |
| AU96 Ltd | Wholesale & retail | 2026 |
| Audio Reflective Ltd | Information & communication | 2015 |
| AUM Pharma Ltd | Health & social care | 2023 |
| Aura Investments (London) Limited | Real estate | 2020 |
| Aurellia Wellness Limited | Wholesale & retail | 2026 |
| Auriona Holdings Ltd | Financial services | 2026 |
| Auto Extreme Ltd | Wholesale & retail | 2008 |
| Autolycus Biomedical Consulting (ABC) Ltd | Health & social care | 2019 |
| Autumnlove Ltd | Professional & scientific | 2022 |
| Avaneesh Technologies Ltd | Information & communication | 2016 |
| Avicenna Holdco Ltd | Financial services | 2017 |
| Avicenna Holdings Ltd | Wholesale & retail | 1994 |
| Avicenna Ltd | Financial services | 2017 |
| Avicenna Midco Ltd | Financial services | 2017 |
| Avicenna Retail Ltd | Wholesale & retail | 2002 |
| Avicenna Topco Ltd | Financial services | 2017 |
| Avondale Flats Management Company Limited | Hospitality | 1986 |
| Avondale House Healthcare Ltd | Health & social care | 2021 |
| Avondale London Limited | Real estate | 2021 |
| Avondale Support Limited | Health & social care | 2020 |
| Awspice Ltd | Hospitality | 2026 |
| Axalin Healthcare Ltd | Health & social care | 2023 |
| AXE Construction Group Ltd | Construction | 2025 |
| AXE Construction Ltd | Construction | 2018 |
| Axena (UK) Limited | Information & communication | 2001 |
| Axion Partners Ltd | Information & communication | 2026 |
| Axis Assets Group Ltd | Real estate | 2026 |
| Ayanssh Investments Limited | Real estate | 2024 |
| Aysa Property Limited | Real estate | 2025 |
| Ayubo Ayurvedic Therapy Ltd | Health & social care | 2022 |
| Ayucare Limited | Health & social care | 2024 |
| Ayvel Limited | Hospitality | 2016 |
| Azaan Support Housing Ltd | Hospitality | 2024 |
| B M Arboriculture Ltd | Agriculture & fishing | 2017 |
| B N D Holdings Limited | Professional & scientific | 1996 |
| B P Flooring Ltd | Construction | 2009 |
| B&C Meat Ltd | Wholesale & retail | 2019 |
| B&Z Narin Ltd | Real estate | 2025 |
| B.P. Thompson Limited | Construction | 2003 |
| Ba&Ro Deco Ltd | Construction | 2024 |
| BAA UBA Ltd | Administrative & support | 2024 |
| BAB EL Babylon Ltd | Information & communication | 2026 |
| Babuckby Limited | Professional & scientific | 2014 |
| Baby Rocket Ltd | Arts & recreation | 2019 |
| Bace Estates Limited | Hospitality | 2020 |
| Back 2 Back Property Ltd | Real estate | 2019 |
| Badgers Rest Management Company Limited | Real estate | 2006 |
| Badgershed Limited | Construction | 2015 |
| BAEMPIRE123 Ltd | Professional & scientific | 2019 |
| Baguette Cafe Limited | Hospitality | 2010 |
| Bahjat Enterprises Ltd | Wholesale & retail | 2024 |
| Bailey-Consulting (CBS) LLP | | 2004 |
| Baldy's Card Breaks Ltd | Wholesale & retail | 2024 |
| Balloon Design by Becky Limited | Arts & recreation | 2022 |
| Baltic Bay Ltd | Professional & scientific | 2022 |
| Bamboo Boost Ltd | Professional & scientific | 2021 |