| A-Z Seafood & Poultry Ltd | Wholesale & retail | 2025 |
| A. C. Read Electrics Ltd | Construction | 2002 |
| A. Ellwood Limited | Professional & scientific | 1932 |
| A.B. Carpets Limited | Other services | 1977 |
| A.B. Group (Croydon) Limited | Financial services | 1959 |
| A.B.M.K Ltd | Hospitality | 2026 |
| A.D.Eclipse Ltd | Real estate | 2019 |
| A.D.S.One Limited | Wholesale & retail | 2003 |
| A.I. Videomatics Ltd | Information & communication | 2022 |
| A.K Builder London Ltd | Construction | 2019 |
| A.L. Concept Limited | Construction | 1997 |
| A.M.S Ophthalmic Opticians (W.P.) Limited | Health & social care | 2009 |
| A.M.S Ophthalmic Opticians Limited | Health & social care | 2009 |
| A.Meli Trade Ltd | Wholesale & retail | 2023 |
| A.N London Taxi Ltd | Transport & logistics | 2021 |
| A.P.B. (UK) Limited | Wholesale & retail | 2011 |
| A.R. Thompson & Associates Flat Management Limited | Professional & scientific | 1991 |
| A.R.G (UK) Limited | Wholesale & retail | 2012 |
| A.R.M. Enterprises (UK) Limited | Other services | 2012 |
| A.S. Mcgill Limited | Manufacturing | 1977 |
| A.T. Studio Limited | Wholesale & retail | 2008 |
| A1 Accountancy (Croydon) LLP | | 2011 |
| A1 Barbers Croydon Limited | Other services | 2021 |
| A1 Builders Croydon Limited | Construction | 2020 |
| A1 Information Technology Services Limited | Information & communication | 2019 |
| A1 UK Solutions Limited | Professional & scientific | 2024 |
| A1 Unity Group Ltd | Professional & scientific | 2024 |
| A1F1 Ltd | Health & social care | 2005 |
| A1HIPS Limited | Wholesale & retail | 2008 |
| A2 Rentals Limited | Real estate | 2026 |
| A2 UK Scaffolding Ltd | Construction | 2022 |
| A2BTRANS Service Ltd | Transport & logistics | 2022 |
| A2K Constructions Ltd | Construction | 2025 |
| A2Z Cle@Ning Ltd | Administrative & support | 2025 |
| A2ZE Ltd | Wholesale & retail | 2024 |
| A2ZI Limited | Hospitality | 2016 |
| A3 Vanisa Ltd | Construction | 2026 |
| A4 Global UK Ltd | Hospitality | 2020 |
| A5 Investments Ltd | Households | 2021 |
| AA Accounting & Financial Services Ltd | Professional & scientific | 2025 |
| AA Engineering Consultancy London Ltd | Extraterritorial | 2016 |
| AA Morgan Auto Servicing and Repair Ltd | Wholesale & retail | 2025 |
| AA Property Partners Limited | Real estate | 2024 |
| AA Rising Cars Ltd. | Wholesale & retail | 2018 |
| AA Service Warlingham Ltd | Wholesale & retail | 2018 |
| AA Smart Homes Ltd | Real estate | 2020 |
| AAA Food Catering Limited | Hospitality | 2024 |
| AAC Advisory Ltd | Other services | 2024 |
| Aachi's Ltd | Hospitality | 2024 |
| Aadarsh Limited | Real estate | 2017 |
| Aadhan Education Technology Limited | Information & communication | 2025 |
| Aafiah Limited | Wholesale & retail | 2024 |
| Aahill Homes Ltd | Real estate | 2026 |
| Aahle Taqwa Ltd | Wholesale & retail | 2025 |
| Aaim Event and Project Management Limited | Transport & logistics | 2017 |
| Aaina Rania Investments Ltd | Real estate | 2021 |
| Aalam Care Limited | Health & social care | 2018 |
| Aalpha Group Limited | Hospitality | 2024 |
| Aama Healthcare Limited | Health & social care | 2023 |
| Aanma Ltd. | Wholesale & retail | 2022 |
| Aann Solution Ltd. | Health & social care | 2012 |
| AAP Ashva Limited | Professional & scientific | 2022 |
| AAP Healthcare Limited | Health & social care | 2021 |
| Aaplus Building Group Ltd | Construction | 2018 |
| Aaps Properties Ltd | Real estate | 2023 |
| AAR Cars Hub Ltd | Wholesale & retail | 2024 |
| Aardcash Ltd | Information & communication | 2019 |
| Aariaan Properties Ltd | Real estate | 2021 |
| Aarkios Health PVT Limited | Wholesale & retail | 2012 |
| Aarn Limited | Information & communication | 2017 |
| Aaron and Keiren Properties Ltd | Real estate | 2024 |
| Aaron Fiyifoluwa Chimsome Odebunmi Limited | Extraterritorial | 2024 |
| Aaron Stitch Ltd | Other services | 2018 |
| Aarons Property Limited | Financial services | 2025 |
| Aarsh UK Ltd | Wholesale & retail | 2023 |
| Aarudhra Ayurvedic Spa Limited | Wholesale & retail | 2024 |
| Aarudhra Groups Limited | Real estate | 2025 |
| Aarya PAL Homes Limited | Real estate | 2026 |
| Aarya Properties Investment Ltd | Real estate | 2020 |
| Aashkama Grange Limited | Hospitality | 2026 |
| Aashkama Limited | Hospitality | 2022 |
| AAT Quality Cars Limited | Wholesale & retail | 2024 |
| AAT Used Quality Cars Ltd | Wholesale & retail | 2025 |
| Aathavan Ltd | Real estate | 2024 |
| Aayashuk Ltd | Wholesale & retail | 2025 |
| Aayat Enterprises Ltd | Wholesale & retail | 2023 |
| AB Car Hire Limited | Transport & logistics | 2006 |
| AB Copains ST Johns Wood Ltd | Wholesale & retail | 2026 |
| AB Copains UK Ltd | Manufacturing | 2025 |
| AB Logistics Group Limited | Transport & logistics | 2026 |
| AB Quantum Talent HR Solutions Ltd | Administrative & support | 2025 |
| ABA Absolute Solutions Limited | Other services | 2014 |
| ABA Defence Solicitors Ltd | Professional & scientific | 2025 |
| ABA Pro Limited | Wholesale & retail | 2018 |
| Aba's Kitchen Restaurant Ltd | Hospitality | 2024 |
| Ababio & Sons Limited | Construction | 2020 |
| Abacus Medical Limited | Administrative & support | 2023 |
| Abacus Mobility Ltd | Transport & logistics | 2018 |
| Abacus Professional Consultancy Limited | Professional & scientific | 2019 |
| Abad Ltd | Wholesale & retail | 2019 |