| Agri-Fencing Ltd | Construction | 2025 |
| Agromac Eguk Ltd | Wholesale & retail | 2026 |
| Agrospecs UK Ltd | Wholesale & retail | 2025 |
| AGS SW Limited | Administrative & support | 2025 |
| AGS Tooting Limited | Administrative & support | 2026 |
| AHA Financial Services Limited | Wholesale & retail | 2019 |
| Ahista Project Limited | Wholesale & retail | 2026 |
| Ahlan Kids Education Ltd | Wholesale & retail | 2020 |
| AI Collaborative Limited | Other services | 2025 |
| AI Consultants Circle Ltd | Information & communication | 2022 |
| AI Engagement Limited | Information & communication | 2025 |
| AI Matrix Learning Ltd | Education | 2024 |
| AI Upskill Ltd | Education | 2022 |
| Aica London Limited | Wholesale & retail | 2021 |
| Aimilios Ltd | Education | 2023 |
| Air One International Holdings Ltd | Transport & logistics | 2012 |
| Air One Services Ltd | Information & communication | 2016 |
| AJ Essentials Ltd | Wholesale & retail | 2025 |
| AJJ Homes Ltd | Real estate | 2024 |
| AK Fencing and Landscaping Limited | Administrative & support | 2015 |
| AK Kooliyo Ltd | Wholesale & retail | 2025 |
| AK Mercury Ltd | Professional & scientific | 2026 |
| Akari Software UK Limited | Information & communication | 2024 |
| AKB Healthcare Limited | Other services | 2024 |
| AKC Asset Management Limited | Wholesale & retail | 2022 |
| AKC Group Ltd | Wholesale & retail | 2019 |
| Akso Heart Limited | Information & communication | 2020 |
| Al-Saharan Ltd | Wholesale & retail | 2026 |
| Alan Wilkins Ltd | Professional & scientific | 2024 |
| Alancordell Limited | Professional & scientific | 2019 |
| Alanna Rose London Ltd | Wholesale & retail | 2021 |
| ALB Home Development Ltd | Construction | 2022 |
| Albaker Properties Limited | Real estate | 2023 |
| Alban Consulting Limited | Professional & scientific | 2001 |
| Albany Riverside Company Limited | Households | 1987 |
| Albatross 2024 Limited | Professional & scientific | 1999 |
| Alberto-Culver Company (U.K.) Limited | Financial services | 1981 |
| Albion Apartments Limited | Real estate | 2020 |
| Albury Park Mansion Freehold Limited | Households | 2018 |
| Albury Park Mansion Management Company Limited | Households | 2015 |
| Alchemist Productions Ltd | Information & communication | 2023 |
| ALD Security Ltd | Wholesale & retail | 2022 |
| Alekraft Ltd | Professional & scientific | 2025 |
| Aleta Studio Ltd | Professional & scientific | 2021 |
| Alex Fergusson Architects Limited | Professional & scientific | 2007 |
| Alex Kravetz Design Limited | Administrative & support | 2007 |
| Alex Zono Limited | Wholesale & retail | 2024 |
| Alexander Advisory Ltd | Professional & scientific | 2025 |
| Alexander Vivian Wealth Management Ltd | Financial services | 2016 |
| Alexandra Mansions RTM Company Limited | Households | 2009 |
| Alexkmr Services Limited | Real estate | 2021 |
| Alfa Style Ltd | Construction | 2015 |
| Alfie Audio Ltd | Arts & recreation | 2026 |
| ALI Baker Limited | Information & communication | 2019 |
| ALI Haider Services Ltd | Wholesale & retail | 2025 |
| Alibaba Education Ltd | Education | 2017 |
| Alimoh Limited | Health & social care | 2025 |
| Alin Carwash Ltd | Other services | 2023 |
| Alison Butters Consulting Limited | Extraterritorial | 2006 |
| Alison Cafe Ltd | Hospitality | 2026 |
| Alkemi London Ltd | Wholesale & retail | 2025 |
| Alkerden Gateway (Ebbsfleet) Residents Management Company Limited | Households | 2024 |
| ALL 4 Property Limited | Construction | 2017 |
| ALL Building Control Certification Limited | Professional & scientific | 2011 |
| ALL Garden Services Limited | Administrative & support | 2024 |
| ALL Guard Roofing and Building Ltd | Construction | 2019 |
| ALL Saints Kingston Development Trust | Arts & recreation | 2011 |
| ALL Things Pilates Ltd | Arts & recreation | 2013 |
| ALL Things Spiritual Limited | Administrative & support | 2021 |
| ALL Tree & Garden Care Ltd | Administrative & support | 2018 |
| Allars Holdings Limited | Financial services | 2025 |
| Allfruit International Limited | Wholesale & retail | 1986 |
| Alliance Consultancy Overseas Limited | Professional & scientific | 2017 |
| Alliance Roofing Solutions Ltd | Construction | 2021 |
| Allied Development (Holdings) Limited | Construction | 1973 |
| Allied Development Group Limited | Professional & scientific | 1970 |
| Almandine (U.K.) Limited | Administrative & support | 1990 |
| Almost Home Cat Cafe CIC | Hospitality | 2026 |
| Aloha Moorgate Ltd | Arts & recreation | 2022 |
| Aloha Richmond Ltd | Arts & recreation | 2022 |
| Alpa Technologies Ltd | Wholesale & retail | 2026 |
| Alph Capital Limited | Financial services | 2016 |
| Alpha Build Project Management Ltd | Construction | 2024 |
| Alpha Build Properties Ltd | Real estate | 2024 |
| Alpha Hotel Management Ltd | Hospitality | 2018 |
| Alpha School of Driving Limited | Education | 2024 |
| Alpha Sparkles Ltd | Administrative & support | 2017 |
| Alpha to Omega Accounting Limited | Professional & scientific | 2006 |
| Alpha-Build-Group Ltd | Construction | 2023 |
| Alpha-Q Investment Management Limited | Financial services | 1997 |
| Alpha-Q Limited | Real estate | 1991 |
| Alpholock Limited | Wholesale & retail | 2023 |
| Alps Building Services Limited | Construction | 2015 |
| Alster Group Ltd | Professional & scientific | 2026 |
| Altease Limited | Wholesale & retail | 2022 |
| Altered Images Limited | Wholesale & retail | 1996 |
| Alterna Energy UK Ltd | Wholesale & retail | 2025 |
| Alva Yoga Limited | Education | 2018 |
| Alvecote Marina Limited | Other services | 2011 |
| Amaba Ltd | Hospitality | 2021 |