| ASC Professional Services Limited | Professional & scientific | 2018 |
| ASC Properties & Investments Limited | Real estate | 2017 |
| Ascension Management Consulting Limited | Professional & scientific | 2018 |
| Ascent RE Agency Ltd | Administrative & support | 2022 |
| Asdirections Ltd | Education | 2024 |
| ASH Contract Services Ltd | Construction | 2015 |
| Ashchurch Developments Limited | Construction | 1990 |
| Ashcode Limited | Information & communication | 2015 |
| Ashdean Limited | Real estate | 2001 |
| Ashdon Business Services Limited | Administrative & support | 2014 |
| Ashfq Mart Solutions Ltd | Wholesale & retail | 2025 |
| Ashgoal Limited | Professional & scientific | 1979 |
| Ashgoal Property Ltd | Real estate | 2025 |
| Ashings CA LLP | | 2007 |
| Ashings Limited | Professional & scientific | 2004 |
| Ashish Group Limited | Wholesale & retail | 2015 |
| Ashleetew Ltd | Financial services | 2026 |
| Ashmor Developments Limited | Construction | 2020 |
| Ashtavinayak Solutions Limited | Health & social care | 2014 |
| Ashwell Electrics Ltd | Construction | 2022 |
| Ashwood Lodge (Barnet) Management Company Limited | Households | 1989 |
| Ashwood Lodge (Freehold) Limited | Households | 1996 |
| Asia Pacific Rocks Ltd | Administrative & support | 2014 |
| Asian Gourmet Limited | Hospitality | 2013 |
| Asiko Studio Ltd | Information & communication | 2007 |
| ASK Gola Holdings Limited | Financial services | 2022 |
| ASK RM Ltd | Real estate | 2023 |
| Askaig Newington Limited | Financial services | 2019 |
| Aslanlar 1 Ltd | Other services | 2023 |
| ASN Consultancy Services Limited | Professional & scientific | 2008 |
| Aspen Vale Services Ltd | Professional & scientific | 2021 |
| Aspetos Ltd | Administrative & support | 2021 |
| Aspiration London Ltd | Administrative & support | 2014 |
| Aspire Live Ltd | Arts & recreation | 2025 |
| Aspiring Product Managers Limited | Information & communication | 2024 |
| Asserta Limited | Information & communication | 2005 |
| Assetstates Limited | Real estate | 1987 |
| Assurance Wills and Estate Planning Limited | Administrative & support | 2019 |
| Assured Guardians Management Ltd | Professional & scientific | 2015 |
| Assured Housing Group Ltd | Real estate | 2021 |
| Ast-Med Ltd | Health & social care | 2019 |
| Astarnumberplates Limited | Wholesale & retail | 2025 |
| Astars Academy Limited | Arts & recreation | 2024 |
| Astramare Limited | Arts & recreation | 2017 |
| Astro Management Limited | Hospitality | 2017 |
| Astute Capital Investments Limited | Real estate | 2009 |
| Asumbo Limited | Other services | 2016 |
| AT Leisure Services Limited | Arts & recreation | 2016 |
| Ataubman Limited | Administrative & support | 2021 |
| Atelier Aesthetics London Ltd | Other services | 2022 |
| Atherton York Group Limited | Financial services | 2020 |
| Atherton York Limited | Financial services | 2013 |
| Atipica Ltd | Health & social care | 2026 |
| Atlas Equipment (London) Limited | Other services | 1946 |
| Atlas Suppliers Limited | Other services | 2024 |
| Atmacha Properties Limited | Real estate | 2022 |
| Atmosphere Ents Limited | Administrative & support | 2010 |
| Atmosphere Faces Ltd | Administrative & support | 2023 |
| Atopi PA Services Ltd | Administrative & support | 2021 |
| Atsi Properties Ltd | Real estate | 2021 |
| Attack Art Co. Ltd | Construction | 2015 |
| Attack Attack (Records) Limited | Information & communication | 1999 |
| Attigo Coaching and Development Ltd | Professional & scientific | 2015 |
| Attractive Properties Limited | Real estate | 2005 |
| Attractive Properties Management Services Limited | Real estate | 2013 |
| Auction Introductions Limited | Real estate | 2022 |
| Audaciousco. Ltd | Wholesale & retail | 2020 |
| Audi Volks Limited | Wholesale & retail | 2006 |
| Audio Vision Ltd | Wholesale & retail | 2016 |
| AUM Capital Holdings Ltd | Real estate | 2025 |
| AUM Sairam Ltd | Wholesale & retail | 2014 |
| Aura Assets Ltd | Real estate | 2020 |
| Aura of Cockfosters Ltd | Hospitality | 2025 |
| Aura Properties Solutions Limited | Real estate | 2022 |
| Aura Software Solutions Limited | Information & communication | 2011 |
| Auratech Systems Limited | Information & communication | 2025 |
| Auravida Property Group Ltd | Real estate | 2025 |
| Aurelia Exports Ltd | Wholesale & retail | 2026 |
| Aureus Automotive Ltd | Wholesale & retail | 2019 |
| Aureus Global Limited | Professional & scientific | 2012 |
| Aureus Group Ltd | Real estate | 2021 |
| Auriga Propco Investments Limited | Financial services | 2022 |
| Aurio Studio Limited | Professional & scientific | 2016 |
| Auron Acre Limited | Real estate | 2025 |
| Aurora AM Ltd | Professional & scientific | 2022 |
| Aurora Beverage Ltd | Real estate | 2019 |
| Aurora Shisha Group Ltd | Hospitality | 2019 |
| Aurum Depot Limited | Wholesale & retail | 2026 |
| Austin Courier Limited | Administrative & support | 2018 |
| Austin D'Arcy Care Services Ltd | Health & social care | 2020 |
| Austin D'Arcy Limited | Real estate | 2012 |
| Authencity Ltd | Information & communication | 2021 |
| Authentic MED Kitchen Ltd | Hospitality | 2025 |
| Authorised Publications Limited | Information & communication | 2009 |
| Auto Center Caps Limited | Wholesale & retail | 2012 |
| Auto Master Centre (LDN) Ltd | Wholesale & retail | 2017 |
| Auto Mobils Ltd | Wholesale & retail | 2022 |
| Autoaxis Ltd | Transport & logistics | 2025 |
| Autobahn INT Limited | Wholesale & retail | 2025 |
| Autoconnect London Limited | Administrative & support | 2024 |