| Academy of Training Ltd | Education | 2024 |
| Accelerated Growth Consulting Ltd | Professional & scientific | 2021 |
| Accentuate Solutions Limited | Education | 2020 |
| Access PA Ltd | Administrative & support | 2020 |
| Access Real Estate Ltd | Construction | 2025 |
| Accounting & Allied Services Limited | Professional & scientific | 2007 |
| Accounts & Taxation Office Ltd | Professional & scientific | 2013 |
| Ace Exteriors Ltd | Construction | 2024 |
| Ace Hair Salon Ltd | Other services | 2020 |
| Ace Poker Nights Ltd | Administrative & support | 2019 |
| Ace Sports Academy Ltd | Education | 2022 |
| Ace Vision Technology Limited | Information & communication | 2016 |
| Achieving for Children Community Interest Company | Public administration | 2014 |
| ACL Property Services Limited | Professional & scientific | 2021 |
| ACM Technology Consulting Ltd | Information & communication | 2025 |
| Acme TV Ltd | Information & communication | 2022 |
| ACO Properties Management Ltd | Construction | 2026 |
| Acorn Laboratories Ltd | Information & communication | 2025 |
| Acroma Limited | Professional & scientific | 2006 |
| Activ Real Estate Solutions Limited | Real estate | 2023 |
| Acton International Limited | Financial services | 2002 |
| Actualise Research Services Ltd. | Professional & scientific | 2016 |
| Acuity AI Limited | Information & communication | 2024 |
| AD Altiora (Filmworks) Ltd | Real estate | 2026 |
| AD BAE Ltd | Professional & scientific | 2025 |
| AD Maiora Digital Limited | Information & communication | 2024 |
| Adair Appleford Limited | Professional & scientific | 2023 |
| Adappt Limited | Administrative & support | 2011 |
| Adaptations Limited | Construction | 2003 |
| Addiena Aurora Ltd | Wholesale & retail | 2018 |
| Addlestones Cuts Ltd | Other services | 2024 |
| Adhax Limited | Information & communication | 2023 |
| Adhraa Botros Ltd | Professional & scientific | 2014 |
| ADI Network Systems Ltd | Information & communication | 2025 |
| Adige Radiators Limited | Wholesale & retail | 2006 |
| ADM Decorators Limited | Construction | 2016 |
| Adnan & Company Limited | Health & social care | 2003 |
| Adorable Food & Wine Ltd | Wholesale & retail | 2025 |
| ADP Training Ltd | Education | 2017 |
| ADS Flex Limited | Construction | 2025 |
| Adtec Europe Limited | Wholesale & retail | 2000 |
| Advance Roofing Ltd | Construction | 2025 |
| Advanced Access Consulting Ltd | Professional & scientific | 2026 |
| Advanced City Plumbing Ltd | Construction | 2014 |
| Advantage 10 Ltd | Education | 2022 |
| Advaya Media Ltd | Education | 2021 |
| Adventure Vehicles Limited | Manufacturing | 2018 |
| Advocate Marketing Communications Limited | Professional & scientific | 2019 |
| AE Tuition Limited | Extraterritorial | 2009 |
| Aecus Partners UK Ltd | Financial services | 2025 |
| AEG Portfolios Limited | Extraterritorial | 2012 |
| Aegean Software & Consultancy Ltd | Information & communication | 2016 |
| AER Digital Ltd | Professional & scientific | 2024 |
| Aerarium Global Ltd | Professional & scientific | 2025 |
| Aesthetic & Laser Clinic of Twickenham Limited | Other services | 2014 |
| Affinity Crew Ltd | Administrative & support | 2002 |
| Aflak General Maintenance & Decoration Limited | Construction | 2021 |
| AFM Bull Ltd | Administrative & support | 2022 |
| Afnco UK Ltd | Wholesale & retail | 2022 |
| Afrolyk Globe Limited | Real estate | 2021 |
| After School Tutors Ltd | Education | 2022 |
| Afton UK Limited | Wholesale & retail | 1987 |
| AG Coffee Limited | Hospitality | 2016 |
| AG Residence Realty Ltd | Real estate | 2025 |
| AGA Colour Ltd | Construction | 2011 |
| Agatewell Ltd | Real estate | 2025 |
| Agenta Compliance Ltd | Health & social care | 2026 |
| Agents Capital Limited | Administrative & support | 2022 |
| Agha Developer and Investor Limited | Hospitality | 2014 |
| Agile Accounting Solutions Ltd | Financial services | 2015 |
| Agility Plus Limited | Professional & scientific | 2012 |
| Agility RMG Limited | Professional & scientific | 2010 |
| AGN Living Ltd | Real estate | 2026 |
| Agnes Trading Ltd | Wholesale & retail | 2021 |
| Agriland Ltd | Real estate | 2016 |
| AH UK Services Ltd | Wholesale & retail | 2023 |
| Ahilans Limited | Wholesale & retail | 2026 |
| AHT 1 Limited | Real estate | 2024 |
| AHT 2 Limited | Real estate | 2024 |
| AI Hypermedia Services Ltd | Wholesale & retail | 2023 |
| AI Press Ltd | Wholesale & retail | 2024 |
| AI Structures & Design Ltd | Professional & scientific | 2024 |
| AI Venture Holdings Ltd | Information & communication | 2025 |
| Aibbs Ltd | Professional & scientific | 2026 |
| Aida Online Marketing Limited | Professional & scientific | 2015 |
| Aidoo Qa-Labs Ltd | Information & communication | 2026 |
| Airmarkt Ltd | Information & communication | 2025 |
| Airport Ontime Limited | Transport & logistics | 2013 |
| Aito - the Specialist Travel Association Ltd | Other services | 1991 |
| Aito Financial Protection Services Ltd | Other services | 2023 |
| Aito Promotions Limited | Other services | 1994 |
| AJ Cars Heathrow Ltd | Wholesale & retail | 2015 |
| AJ Doors & Windows Ltd | Construction | 2024 |
| AJI Limited | Wholesale & retail | 2025 |
| Ajtg Ltd | Professional & scientific | 2018 |
| Akada International Trading Limited | Other services | 2020 |
| Akart Design & Build Ltd | Construction | 2025 |
| Akart Limited | Construction | 2019 |
| Akashkamboj Ltd | Construction | 2023 |
| Akira Hospitality Ltd | Wholesale & retail | 2019 |