| ADP & Son’S Services Ltd | Construction | 2026 |
| Adrian Barnardo Ltd | Health & social care | 2014 |
| Adrian Pentecost Fires by Design Ltd | Construction | 2014 |
| Adriax Labs Ltd | Information & communication | 2026 |
| Adroit Cloud Consulting Limited | Information & communication | 2020 |
| ADV Services South East Limited | Administrative & support | 2025 |
| Adval Investments Limited | Financial services | 2023 |
| Advance Careers Limited | Education | 2017 |
| Advance Concrete Ltd | Manufacturing | 2025 |
| Advance Safety Ltd | Professional & scientific | 2026 |
| Advanced Bird Solutions Limited | Professional & scientific | 2016 |
| Advanced Power Engineering Solutions Ltd | Professional & scientific | 2013 |
| Advanced Radiology Ltd | Health & social care | 2015 |
| Advancetec Solutions Ltd | Construction | 2022 |
| Advantage Catering Equipment Limited | Manufacturing | 2008 |
| Advantage Security Services Ltd | Administrative & support | 2019 |
| Advizr Ltd | Professional & scientific | 2022 |
| ADY Educate Ltd | Education | 2014 |
| Adya Enterprises Ltd | Real estate | 2023 |
| AE Kent Ltd | Hospitality | 2024 |
| Aegean Gold Designs Ltd | Wholesale & retail | 2015 |
| Aegirshold Ltd | Wholesale & retail | 2025 |
| Aegis Financial Planning Limited | Financial services | 2014 |
| Aeliza Ltd | Administrative & support | 2020 |
| AEP Properties Limited | Construction | 2017 |
| Aerial Advantage Ltd | Professional & scientific | 2019 |
| Aerial Target Technology Limited | Manufacturing | 2018 |
| Aero Keen Ltd | Professional & scientific | 2025 |
| Aerotech Consulting Services Limited | Information & communication | 2020 |
| Aerotyne IND Ltd | Manufacturing | 2020 |
| Aeroventure Ltd | Professional & scientific | 2022 |
| AES Prop Co Limited | Real estate | 2023 |
| Aesthetic Associates Limited | Other services | 2020 |
| AF Property Invest (UK) Ltd | Real estate | 2023 |
| AFB Mobile Limited | Wholesale & retail | 2025 |
| Affinity Associates (AU) Limited | Professional & scientific | 2018 |
| Affinity Business Solutions Limited | Professional & scientific | 2026 |
| AFFIRM8 Consultancy Ltd | Professional & scientific | 2022 |
| AFH Property Management Ltd | Real estate | 2019 |
| African Warrior Ltd | Health & social care | 2024 |
| Afritech Geoscience Limited | Professional & scientific | 2015 |
| Afrofits Atelier Limited | Wholesale & retail | 2026 |
| AFS Cable Limited | Professional & scientific | 2008 |
| AG Bartlett Consultancy Ltd | Professional & scientific | 2025 |
| AG Russell Plant Hire Ltd | Administrative & support | 2023 |
| Agape Yarusam UK Ltd | Extraterritorial | 2006 |
| AGC (Kent) Limited | Administrative & support | 2024 |
| AGC Landscapes Ltd | Administrative & support | 2019 |
| AGD Surgical Services Ltd | Health & social care | 2024 |
| Agency Sector Management (U.K.) Limited | Information & communication | 1986 |
| Agensia Ltd | Professional & scientific | 2025 |
| Agile Business Consortium Limited | Information & communication | 1995 |
| Agile Business Products Limited | Information & communication | 2022 |
| Aglent General Elec Tech Ltd | Wholesale & retail | 2023 |
| AGM Advisers Limited | Administrative & support | 2020 |
| AGM Properties Solutions Limited | Real estate | 2022 |
| Agnelli Consulting Ltd | Professional & scientific | 2023 |
| AGP Real Estate Limited | Construction | 2022 |
| Agri Tune UK Limited | Manufacturing | 2022 |
| Agrimanagement Limited | Agriculture & fishing | 1977 |
| AGS 2021 Ltd | Transport & logistics | 2021 |
| AGS Photography Limited | Professional & scientific | 2025 |
| AH Joinery Services Limited | Manufacturing | 2006 |
| AH Zaidi Properties Ltd | Real estate | 2023 |
| Aheer Estates Ltd | Real estate | 2021 |
| Ahrn Ltd | Health & social care | 2024 |
| AI Property Solutions Ltd | Construction | 2023 |
| Aic-It Limited | Information & communication | 2000 |
| AID With Care Limited | Health & social care | 2015 |
| Aidex Geneva Limited | Administrative & support | 2022 |
| Aidinaujokas Ltd | Wholesale & retail | 2025 |
| Aidkin Consulting Limited | Information & communication | 2014 |
| AIG 1 Ltd | Real estate | 2023 |
| Aigas Consulting Limited | Real estate | 2023 |
| Aimer Catering Ltd | Hospitality | 2025 |
| Aims Accountants for Business Ltd | Administrative & support | 2024 |
| Aims Accountants Ltd | Administrative & support | 2024 |
| Aims AFB Ltd | Financial services | 2023 |
| Aims Financial Limited | Financial services | 1997 |
| Aims Projects Ltd | Information & communication | 2017 |
| Aiova Ltd | Information & communication | 2014 |
| Air Courier Worldwide Express Limited | Transport & logistics | 2002 |
| Air Source Heating & Cooling Ltd | Construction | 2024 |
| Air-Line Systems Holdings Limited | Financial services | 2015 |
| Air-Line Systems Limited | Manufacturing | 2003 |
| Airborne Adventures Headcorn Ltd | Arts & recreation | 2000 |
| Airclean Limited | Manufacturing | 1988 |
| Airfield Design Ltd | Other services | 2010 |
| Airlink EXP Services Limited | Transport & logistics | 2025 |
| Airport Chauffeur Services Ltd | Transport & logistics | 2024 |
| Airs Consulting Limited | Professional & scientific | 2024 |
| Airsealand Industries Holdings (UK) Ltd. | Professional & scientific | 2013 |
| AIS Managed Services Ltd | Information & communication | 2013 |
| Aisle-X Ltd | Wholesale & retail | 2025 |
| Aitch Property Limited | Real estate | 2021 |
| Aiyantr Ltd | Information & communication | 2020 |
| AJ Locke Consulting Engineers Ltd | Professional & scientific | 2008 |
| AJ Pressure Solutions Ltd | Administrative & support | 2025 |
| AJ Tuning Ltd | Wholesale & retail | 2025 |
| Aj&C Services Limited | Other services | 2005 |