| Athelston Properties Holdings Limited | Real estate | 2025 |
| Athelston Properties Limited | Real estate | 2018 |
| Atilda Global Solutions Ltd | Wholesale & retail | 2026 |
| Atlan Holdings Limited | Real estate | 2025 |
| Atlansolutions Limited | Real estate | 2011 |
| Atlantis FM Ltd | Real estate | 2015 |
| Atlanuk Ltd | Information & communication | 2025 |
| Atlas Partners (Sydenham) Ltd | Other services | 2015 |
| Atomic Tangerine Holdings Limited | Administrative & support | 2012 |
| Atrif Limited | Manufacturing | 2018 |
| Attoe Building Design Limited | Professional & scientific | 2015 |
| Audiohustler Limited | Information & communication | 2013 |
| Aufgehen Ltd | Wholesale & retail | 2024 |
| Augmentity Limited | Professional & scientific | 2018 |
| Aura Investment Limited | Real estate | 2014 |
| Aureo Marine Ltd | Wholesale & retail | 2026 |
| Austin James Recruitment Limited | Administrative & support | 2009 |
| Auto Assist Group Ltd | Wholesale & retail | 2025 |
| Auto IT Infotech Ltd | Information & communication | 2021 |
| Auto Mechanical & Electrical Solutions Limited | Construction | 2022 |
| Automata Commerce Limited | Wholesale & retail | 2026 |
| Automateks Limited | Information & communication | 2023 |
| Automatic Fire Mist Solutions Limited | Professional & scientific | 2022 |
| Automatic Fire Stop Solutions Limited | Professional & scientific | 2022 |
| Automatic Sprinker Solutions Holdings Limited | Professional & scientific | 2020 |
| Automatic Sprinkler Solutions Ltd | Administrative & support | 2010 |
| Automotive Group Holdings Limited | Professional & scientific | 2008 |
| Automotive Property Group Limited | Wholesale & retail | 2013 |
| Automotive Repair Systems (Booth) Limited | Wholesale & retail | 2019 |
| Automotive Repair Systems (DCD) Limited | Wholesale & retail | 2019 |
| Automotive Repair Systems (Dents) Limited | Wholesale & retail | 2019 |
| Automotive Repair Systems (Paint) Limited | Wholesale & retail | 2019 |
| Automotive Repair Systems (Wheels) Limited | Wholesale & retail | 2019 |
| Automotive Repair Systems Limited | Wholesale & retail | 2001 |
| Autumnwood Services Limited | Real estate | 2026 |
| AV Group Capital Limited | Professional & scientific | 2026 |
| Avant Chauffeurs Ltd | Transport & logistics | 2025 |
| Avant Garde Retail Group Ltd | Wholesale & retail | 2023 |
| Avanti Trucking Ltd | Transport & logistics | 2019 |
| Avenlex Services Limited | Administrative & support | 2026 |
| Aventa Ltd | Wholesale & retail | 2023 |
| Aventra Capital Ltd | Real estate | 2025 |
| Aviation Finance Solutions Limited | Financial services | 2012 |
| Avident Limited | Health & social care | 2025 |
| Avielacare Ltd | Health & social care | 2021 |
| Avighna SN Limited | Real estate | 2024 |
| Avini Bespoke Interiors Ltd | Wholesale & retail | 2014 |
| Avinit Tattoo & Body Piercing Limited | Other services | 2004 |
| Avinitechnologies Limited | Information & communication | 2025 |
| Avinto Ltd | Households | 2023 |
| AVK Properties Ltd | Real estate | 2018 |
| AVM Dentl Limited | Administrative & support | 2026 |
| AVM Dentl Partnership LLP | | 2026 |
| Avni Viraj Real Estate Limited | Real estate | 2024 |
| Avon Oak Construction Limited | Construction | 2021 |
| Avonhurst Limited | Real estate | 2024 |
| Avtrac (UK) Limited | Other services | 1992 |
| Avtrac International Limited | Extraterritorial | 2010 |
| Avtrac Limited | Extraterritorial | 2010 |
| AW Aviation Group Ltd | Professional & scientific | 2025 |
| AWA Fixara Ltd | Information & communication | 2025 |
| Awesome Grace Ltd. | Health & social care | 2012 |
| Awesome Hands Facilities Ltd | Administrative & support | 2025 |
| AWR Building & Maintenance Services Limited | Administrative & support | 2016 |
| AWS (Kent) Holdings Limited | Administrative & support | 2022 |
| AWS (Kent) Limited | Construction | 2022 |
| AWS Electrical Services Limited | Construction | 2019 |
| AWT Electrical Limited | Construction | 2019 |
| Axessible Technologies UK Ltd | Information & communication | 2026 |
| Axiom Apartments (Bromley) RTM Company Limited | Households | 2015 |
| Axium Consulting Ltd | Information & communication | 2025 |
| AY3 Property Ltd | Real estate | 2024 |
| Ayden Investments Limited | Real estate | 2020 |
| Ayerst Environmental Limited | Administrative & support | 1985 |
| Ayre Holdings Limited | Financial services | 2025 |
| Ayspire Ltd | Professional & scientific | 2018 |
| Ayyar Ltd | Real estate | 2019 |
| AZ Relocate Ltd | Real estate | 2024 |
| Azendel Asset Management Limited | Real estate | 2021 |
| Aziz (Holdings) Limited | Real estate | 1965 |
| Aziz Investments Limited | Real estate | 1964 |
| Azlor Properties Ltd | Real estate | 2021 |
| Aztech Fire & Security Systems Ltd | Administrative & support | 2025 |
| B & F Company | | 1996 |
| B & H Building & Installations Limited | Construction | 2015 |
| B & H Home Store Ltd | Wholesale & retail | 2025 |
| B&B Valeting Limited | Administrative & support | 2025 |
| B&N Building Construction Ltd | Construction | 2022 |
| B'S Coffee Shop Ltd | Wholesale & retail | 2025 |
| B.R. Flooring Ltd | Wholesale & retail | 2011 |
| B.T.A.N Chelsfield Ltd | Other services | 2023 |
| B.W.T Construction Ltd | Construction | 2017 |
| B2B Media Group UK Limited | Professional & scientific | 2021 |
| B4 Builders Ltd | Construction | 2017 |
| Baan Thai Kentish Ltd | Hospitality | 2019 |
| Babbage & Beyond Consulting Ltd | Information & communication | 2025 |
| Baberdown Limited | Administrative & support | 2021 |
| Babraopio Healthcare Services Limited | Health & social care | 2022 |
| Babtee Little Angel Childcare Limited | Health & social care | 2025 |
| Baby Knit London Limited | Wholesale & retail | 2024 |