| A.Larkin(Concrete)Limited | Manufacturing | 1956 |
| A.O.M Developments Ltd | Real estate | 2022 |
| A.T.L Entertainment Ltd | Information & communication | 2019 |
| A.Z.K Limited | Administrative & support | 2022 |
| A1 Cars Limited | Transport & logistics | 2002 |
| A1 Holloway Car, Van & Minibus Rentals Limited | Administrative & support | 2016 |
| A1 Party Services Ltd | Hospitality | 2019 |
| A20 Cleaning Services Ltd | Administrative & support | 2020 |
| A2Z Airport Parking Ltd | Transport & logistics | 2017 |
| A2Z Surgical Ltd | Other services | 2021 |
| A3 Mart Ltd | Wholesale & retail | 2013 |
| AA & a Properties Ltd | Real estate | 2025 |
| AA COM Limited | Wholesale & retail | 2007 |
| AA Investment Holdings Ltd. | Real estate | 2016 |
| AA Phone & Vape Limited | Wholesale & retail | 2024 |
| AA Property Ventures Ltd | Real estate | 2021 |
| AA Tech Services Limited | Information & communication | 2026 |
| AAK Convenient Store Limited | Wholesale & retail | 2025 |
| AAK Group Ltd | Wholesale & retail | 2019 |
| AAR Builders Limited | Construction | 2015 |
| Aara Thaamira Limited | Wholesale & retail | 2020 |
| Aarani and Aarujan Ltd | Wholesale & retail | 2018 |
| Aarushi Ltd | Households | 2025 |
| Aathii Properties Ltd | Real estate | 2026 |
| Aatronixdeals Ltd | Wholesale & retail | 2026 |
| AB Fruits-Vegs Ltd | Wholesale & retail | 2026 |
| Abbys Grill Peri Peri (Tooting Branch) Limited | Hospitality | 2019 |
| Abbys Grill Peri Peri Limited | Hospitality | 2014 |
| Abcisco Group Ltd | Administrative & support | 2022 |
| ABH Laundry Service Ltd | Other services | 2026 |
| Abi's Hair & Beauty Spa Limited | Other services | 2013 |
| Abosede Asorona Health Care Ltd. | Health & social care | 2021 |
| Above and Below Ground Works Ltd | Construction | 2023 |
| Above Ground Heating Ltd | Construction | 2024 |
| Abrams Associates Limited | Professional & scientific | 2003 |
| Abrepo Junction Supermarket Ltd | Wholesale & retail | 2010 |
| Absolute Resource Limited | Transport & logistics | 2021 |
| ABU Hassan AL Noori Ltd | Wholesale & retail | 2025 |
| Abygail Investments Limited | Health & social care | 2022 |
| AC Plus Ltd | Construction | 2017 |
| Accident Claim Solutions (UK) Limited | Professional & scientific | 2007 |
| Accomodation Solutions Ltd | Administrative & support | 2022 |
| Accountants DEN Ltd | Professional & scientific | 2024 |
| Accoutre Centre for Learning C.I.C. | Education | 2020 |
| Accurate Healthcare Ltd | Public administration | 2016 |
| Acdd Ltd | Mining & quarrying | 2007 |
| Ace 1J Ltd | Financial services | 2023 |
| Ace 8 Ltd | Financial services | 2025 |
| Ace 9 Ltd | Real estate | 2025 |
| Ace Building and Design Ltd | Construction | 2024 |
| Ace Empower Care Limited | Health & social care | 2024 |
| Ace GB Properties Limited | Real estate | 2018 |
| Ace Point Limited | Real estate | 2019 |
| Acre Mills (UK) Limited | Extraterritorial | 1939 |
| AD Amoah-Arko Ltd | Health & social care | 2024 |
| AD Beauty Base Ltd | Other services | 2025 |
| Adam Carpenter Ltd | Construction | 2026 |
| Adam Financial Ltd | Professional & scientific | 2024 |
| Adam Sully Ltd | Information & communication | 2018 |
| Addamps Limited | Health & social care | 2026 |
| Addiescart Ltd | Wholesale & retail | 2026 |
| Addison Grace Limited | Extraterritorial | 2023 |
| Adedede Enterprises Ltd | Construction | 2026 |
| Adept Accountax Ltd | Professional & scientific | 2020 |
| Adept Advisors Ltd | Professional & scientific | 2021 |
| Adept Consultants Ltd | Administrative & support | 2024 |
| Adept Wealth Management Advisory Ltd | Financial services | 2023 |
| Adewarnerphotouk Ltd | Professional & scientific | 2018 |
| Adil CH Ltd | Wholesale & retail | 2025 |
| Admin Consultancy Ltd | Professional & scientific | 2024 |
| Admin Shine Limited | Administrative & support | 2023 |
| Admin Skill Limited | Administrative & support | 2022 |
| Adnan Consultancy Ltd | Other services | 2016 |
| Adoace Limited | Professional & scientific | 2024 |
| Adoace Services Ltd | Construction | 2025 |
| Adom Holdings Ltd | Construction | 2026 |
| Adonai Media Ltd | Professional & scientific | 2016 |
| ADP Global UK Limited | Wholesale & retail | 2010 |
| Adraix Ltd | Professional & scientific | 2026 |
| Advanced Construction Ltd | Construction | 2021 |
| Advoco Software Limited | Information & communication | 2016 |
| Aerobit Technologies Limited | Information & communication | 2019 |
| Aethercore Nexus Ltd | Wholesale & retail | 2024 |
| AF Alliance Ltd | Other services | 2025 |
| AF Style & Tech Ltd | Wholesale & retail | 2026 |
| Afbro Services Limited | Transport & logistics | 2011 |
| AFC Engineering Services Ltd | Professional & scientific | 2025 |
| AFC Supply Ltd | Wholesale & retail | 2026 |
| Affhan International Ltd | Wholesale & retail | 2020 |
| Affhan Shipping Ltd | Wholesale & retail | 2025 |
| Affront Capital Consulting Limited | Financial services | 2026 |
| AFI Akos Ltd | Wholesale & retail | 2019 |
| AFK International Ltd | Wholesale & retail | 2025 |
| AFO Business Import Ltd | Administrative & support | 2018 |
| Africa Connect International UK Ltd | Wholesale & retail | 2025 |
| Africanamericangroup Limited | Hospitality | 2025 |
| AFS Legion Limited | Wholesale & retail | 2020 |
| Aftab Ahmad Ltd | Transport & logistics | 2015 |
| Aftergram Limited | Wholesale & retail | 2012 |
| Agaam Building Services Ltd | Construction | 2025 |