| Alter&Cope Limited | Real estate | 2021 |
| Alternative Eco Solutions UK Ltd | Other services | 2020 |
| Alternative USE Boston Projects Limited | Energy | 2017 |
| Alvi Electrical Ltd | Construction | 2025 |
| Alvid Holdings Limited | Professional & scientific | 2002 |
| Alvid Investment Company Limited(The) | Construction | 1969 |
| Alwyns LLP | | 2010 |
| Alwyns Partners Limited | Administrative & support | 2011 |
| ALX Recovery Ltd | Transport & logistics | 2026 |
| ALY Cars Ltd | Manufacturing | 2025 |
| AM Propco Limited | Real estate | 2021 |
| Amado Move Circuit Ltd | Other services | 2025 |
| Amae Limited | Financial services | 2018 |
| Amala Aesthetics Limited | Health & social care | 2022 |
| Amato Catering Ltd | Hospitality | 2025 |
| Amber Facial Spa Ltd | Other services | 2021 |
| Ambleside Consulting Limited | Professional & scientific | 2006 |
| Ambresbury Care Limited | Health & social care | 2020 |
| Ambrose Building Solutions Ltd | Construction | 2026 |
| Amco (London) Building Services Limited | Construction | 2025 |
| Amena Subs Ltd | Wholesale & retail | 2019 |
| AMG Mgmt Ltd | Transport & logistics | 2023 |
| Amicos Advisors Limited | Administrative & support | 2023 |
| Amida Bakery Ltd | Wholesale & retail | 2025 |
| Amins Build Rights Ltd | Construction | 2026 |
| Amir Investment Ltd | Real estate | 2022 |
| Amka HR Consultancy Ltd | Professional & scientific | 2023 |
| Amoalites Ltd | Health & social care | 2024 |
| Amor Brothers Ltd | Real estate | 2021 |
| Amplap Limited | Transport & logistics | 2007 |
| Amplfy Coaching Ltd | Arts & recreation | 2025 |
| Amplfy Limited | Wholesale & retail | 2024 |
| Amplify SIX Ltd | Real estate | 2023 |
| AMS & Partners Limited | Other services | 2021 |
| Amsaal Enterprise LLP | | 2016 |
| Amsaal Property Developments Limited | Construction | 2013 |
| Amsair Aircraft Limited | Transport & logistics | 2006 |
| Amseu Ltd | Wholesale & retail | 2018 |
| Amshold Group Limited | Real estate | 2013 |
| Amshold International Limited | Real estate | 1999 |
| Amshold Limited | Real estate | 2019 |
| Amshold Securities Limited | Financial services | 1997 |
| Amshold Trading Limited | Professional & scientific | 2013 |
| Amsprop Bishopsgate Limited | Real estate | 2006 |
| Amsprop Charterhouse Limited | Construction | 2019 |
| Amsprop Estates Limited | Real estate | 1993 |
| Amsprop Investments Limited | Real estate | 1990 |
| Amsprop Leyton Limited | Construction | 2019 |
| Amsprop Limited | Financial services | 1984 |
| Amsprop London Limited | Real estate | 1989 |
| Amsprop NV Limited | Real estate | 2023 |
| Amsprop Property Company Limited | Construction | 2019 |
| Amsprop Reat Limited | Construction | 1995 |
| Amsprop Soho Limited | Construction | 2020 |
| Amsprop USA Holdings Limited | Transport & logistics | 2001 |
| Amsprop USA Property Limited | Real estate | 2014 |
| Amsprop Welwyn Limited | Construction | 2019 |
| Amsprop Winchester Limited | Construction | 2019 |
| Amstar Entertainment Limited | Manufacturing | 2007 |
| Amstar Media Limited | Information & communication | 2014 |
| Amstrad Digital Limited | Professional & scientific | 2023 |
| Amstrad Limited | Information & communication | 2024 |
| Amsvest Limited | Financial services | 2011 |
| AMU Pubs Ltd | Hospitality | 2012 |
| Amuse East London Limited | Arts & recreation | 2011 |
| AMV Holdco Limited | Real estate | 2024 |
| AMV Property Holdings Limited | Real estate | 2024 |
| AMY Clark Interior Design Ltd | Professional & scientific | 2021 |
| Amzlab Limited | Wholesale & retail | 2024 |
| Anakao Jewellery Ltd | Wholesale & retail | 2015 |
| Anambra State Union United Kingdom (ASU UK) | Other services | 2021 |
| Anata Tiling Ltd | Construction | 2026 |
| ANBU3 Limited | Real estate | 2020 |
| Anderson Mori & Tomotsune UK Limited | Professional & scientific | 2022 |
| Anderson Sinclair Contracts Ltd | Wholesale & retail | 2006 |
| Anderson Sinclair Group Ltd | Financial services | 2023 |
| Anderson Sinclair Limited | Wholesale & retail | 2009 |
| Andreas & Co Property Services Ltd | Real estate | 2023 |
| Andrew Bellman Global Risk Ltd | Administrative & support | 2013 |
| Andrew Ratnage Ltd | Education | 2025 |
| Andy P Medical Services Ltd | Health & social care | 2022 |
| Anfield South Ltd | Hospitality | 2024 |
| Angel and Sons Road and Rail Engineers Limited | Manufacturing | 2015 |
| Angel Estates (London) Ltd | Real estate | 2001 |
| Angelos World Ltd | Wholesale & retail | 2019 |
| Anglesey Street Ltd | Real estate | 2016 |
| Anglo Indian Beverage Ltd | Hospitality | 2012 |
| Aniele 64 Ltd | Construction | 2019 |
| Animatic AI Solutions Ltd | Information & communication | 2024 |
| Anjsd Limited | Real estate | 2025 |
| Anmac Interiors Limited | Construction | 2012 |
| Anna Heywood Consultancy Ltd | Professional & scientific | 2015 |
| Annagrace Capital Advisors Limited | Financial services | 2018 |
| Annandale Property Investments Ltd | Real estate | 2019 |
| Annika Investments Ltd | Real estate | 2021 |
| Anoushka G London Limited | Extraterritorial | 2003 |
| Ansis Partners LLP | | 2020 |
| Answerfast (Holdings) Limited | Information & communication | 2024 |
| Answerfast (International) Ltd | Administrative & support | 2024 |
| Answerfast People Limited | Administrative & support | 2024 |