| 1912 Properties Limited | Real estate | 2020 |
| 255 Squires Lane (Freehold) Ltd | Households | 2002 |
| 2617 Limited | Wholesale & retail | 2015 |
| 263 East END Road (Freehold) Limited | Households | 2008 |
| 3-WAVE Consultancy Ltd | Administrative & support | 2010 |
| 315 Regents Park Road Limited | Real estate | 2007 |
| 39 Dennington Park Road Management Company Limited | Real estate | 2000 |
| 43 Station RD N3 Ltd | Households | 2016 |
| 49 Bushey Hall Road Freeholders Limited | Households | 2007 |
| 5 Etchingham Park Road Limited | Households | 1969 |
| 50 Manor Road Freehold Limited | Real estate | 2004 |
| 7 Hampstead High Street Limited | Real estate | 2017 |
| 72 Hair Limited | Manufacturing | 2016 |
| 80 Hendon Lane Management Limited | Real estate | 1995 |
| 93 Sunny Gardens Road (1997) Limited | Households | 1997 |
| A & T Corporation Limited | Other services | 2009 |
| A Blue (UK) Limited | Construction | 2012 |
| A J Palmer (Welding and Fabrications) Limited | Manufacturing | 2004 |
| A P Printing Limited | Other services | 2013 |
| A Tailor's CUT Ltd | Extraterritorial | 2018 |
| A to B Glass & Glazing Limited | Construction | 1999 |
| A.F.D. (Properties) Limited | Real estate | 1982 |
| AA29 Limited | Education | 2014 |
| Ab&S Limited | Hospitality | 2023 |
| Abilitiez Ltd | Administrative & support | 2016 |
| ABN Media Invest Ltd | Information & communication | 2016 |
| Access to Counselling and Therapy | Professional & scientific | 2015 |
| Accident Management Advice Limited | Professional & scientific | 2005 |
| Accounting Works (2005) Limited | Professional & scientific | 2005 |
| Accuspan Limited | Manufacturing | 2023 |
| Ace Asbestos Limited | Other services | 2006 |
| Achievemed Ltd | Health & social care | 2016 |
| Acme Receptive Limited | Administrative & support | 2000 |
| Active Bolt Ltd | Transport & logistics | 2023 |
| Adam Klein Consultants Limited | Financial services | 2017 |
| Addictive AMP Holdings Limited | Financial services | 2011 |
| Addison Freehold Ltd | Households | 2022 |
| Adept Financial Solutions Ltd | Financial services | 2015 |
| ADG Residential Limited | Real estate | 2021 |
| Adrimaa Limited | Hospitality | 2021 |
| Advanced Agents Ltd | Real estate | 2018 |
| Advanced Beauty Medical Clinics Limited | Health & social care | 2024 |
| Advanced Roofing & Insulation Contractors Ltd | Construction | 2025 |
| Aegean Heritage Foods Limited | Wholesale & retail | 2014 |
| Aegean Heritage Ltd. | Wholesale & retail | 1993 |
| Aegean Holdings Ltd | Financial services | 2022 |
| Aerotraders Limited | Wholesale & retail | 2014 |
| After Noah Limited | Wholesale & retail | 1990 |
| AGP Property Investments Limited | Real estate | 2022 |
| Ahab Property Investments Limited | Other services | 2022 |
| Ahura Restaurant Ltd | Hospitality | 2011 |
| AK Space Ltd | Real estate | 2021 |
| Albacor Software Limited | Information & communication | 1986 |
| Aletheia GI Holdings Ltd | Information & communication | 2026 |
| Aletheia GI Ltd | Information & communication | 2026 |
| Alexi Enterprises LLP | | 2015 |
| Alia Fast Food Limited | Hospitality | 2017 |
| Alinco Consultants Limited | Professional & scientific | 2000 |
| Aliven Health Ltd | Health & social care | 2026 |
| Allan and Sons Holdings Ltd | Financial services | 2025 |
| Allan and Sons Limited | Other services | 2020 |
| Allbright Collective Limited | Other services | 2023 |
| Alletante Limited | Health & social care | 2017 |
| Alma Mater Real Estate UK Limited | Real estate | 2023 |
| Altias Holdings Limited | Professional & scientific | 2015 |
| Altman Placks Properties Limited | Real estate | 2016 |
| Amarni Solutions Ltd | Information & communication | 2008 |
| Amaze Global Ltd | Professional & scientific | 2023 |
| Ambergale Ltd | Education | 2001 |
| AMC Labs Ltd | Professional & scientific | 2026 |
| Ampman Audio Services Ltd | Other services | 2012 |
| Andrew Hawker Financial Management Limited | Financial services | 1997 |
| Anjaljun Holdings Ltd | Professional & scientific | 2010 |
| Annova (UK) Ltd | Wholesale & retail | 2004 |
| Aplos Housing Resources Limited | Information & communication | 2025 |
| Apollo Bathrooms Limited | Wholesale & retail | 2019 |
| Apposta Ltd | Wholesale & retail | 2015 |
| Aquarium Design Centre Limited | Professional & scientific | 1991 |
| Aquatic Design Centre Limited | Other services | 1991 |
| Aquatic Design Limited | Professional & scientific | 1998 |
| Archanaeum Limited | Professional & scientific | 2016 |
| Archway Architectural Designs Ltd | Professional & scientific | 2013 |
| Ariadne Insight Limited | Information & communication | 2011 |
| Arrle Tailoring Ltd | Other services | 2023 |
| Art AI Ltd | Arts & recreation | 2019 |
| Arya Private Credit Limited | Financial services | 2025 |
| ASA Market Investments Limited | Financial services | 2017 |
| Ascelis Bridge Limited | Financial services | 2025 |
| Ascelis Capital Limited | Financial services | 2025 |
| Ascelis Finance Limited | Financial services | 2025 |
| Ascelis Group Limited | Financial services | 2025 |
| Ascelis International Limited | Financial services | 2025 |
| Ascelis Investment Limited | Financial services | 2025 |
| Ascelis Lending Limited | Financial services | 2025 |
| Ascelis Limited | Financial services | 2025 |
| Ascelis Loans Limited | Financial services | 2025 |
| Ascelis Money Limited | Financial services | 2025 |
| Ascelis Solutions Limited | Financial services | 2025 |
| Ascelis Wealth Limited | Financial services | 2025 |
| Asha Cakes Limited | Hospitality | 2012 |