| Agfa UK Group Pension Plan Trustee Limited | Financial services | 2000 |
| Aghoco 2049 Limited | Extraterritorial | 2021 |
| Aghoco 2352 Limited | Extraterritorial | 2025 |
| AGI Agents Ltd | Information & communication | 2023 |
| Agile 101 Consulting Ltd | Information & communication | 2021 |
| Agile Consulting Ltd | Information & communication | 2018 |
| Agile Delivery Services Limited | Professional & scientific | 2021 |
| Agile Elite Ltd | Extraterritorial | 2022 |
| Agile Tech Ltd | Information & communication | 2010 |
| Agile.Soft Information Technology Consultants Limited | Information & communication | 2012 |
| Agileague Limited | Information & communication | 2015 |
| Agilered Ltd | Wholesale & retail | 2018 |
| Agilezone Ltd | Information & communication | 2019 |
| Agility DGS UK Limited | Transport & logistics | 2009 |
| Agkc (UK) Limited | Administrative & support | 2011 |
| Agoh Limited | Wholesale & retail | 2025 |
| Agpc Hygiene Ltd | Wholesale & retail | 2022 |
| AGR Pizza Ltd | Hospitality | 2016 |
| Agrimetrics Trading Company Limited | Professional & scientific | 2024 |
| Agriska Associates Limited | Professional & scientific | 2024 |
| AH Dealz Ltd | Wholesale & retail | 2023 |
| AH Financial Services Ltd | Professional & scientific | 2020 |
| AH Global Trading Ltd | Wholesale & retail | 2026 |
| AH Plumbing Ltd | Construction | 2023 |
| Ahead Garden Design Services Limited | Other services | 1994 |
| Ahead Garden Services Limited | Other services | 1994 |
| Aherne-Conroy Consulting Limited | Information & communication | 2011 |
| AHG 46 Ltd | Hospitality | 2023 |
| AHJ Services Ltd | Wholesale & retail | 2025 |
| AHL Electrical Ltd | Construction | 2007 |
| Ahluwalia Family Office Limited | Real estate | 2021 |
| AHM Cars Ltd | Transport & logistics | 2025 |
| Ahmad Catering Services Ltd | Hospitality | 2025 |
| Ahmaira Ltd | Wholesale & retail | 2020 |
| Ahmed Chem Ltd | Health & social care | 2008 |
| Ahmed Mukhtar Ltd | Professional & scientific | 2000 |
| Ahmed Superstore Ltd | Wholesale & retail | 2021 |
| Ahmedwaqas Limited | Hospitality | 2023 |
| Ahmz Cars Ltd | Administrative & support | 2024 |
| Ahongkauiok Online Education Ltd | Education | 2026 |
| Ahzain Limited | Real estate | 2024 |
| Ahzee Mart Limited | Wholesale & retail | 2025 |
| AI Aqua ZIP UK Limited | Financial services | 2017 |
| AI Botify Limited | Wholesale & retail | 2024 |
| AI Commercials Ltd | Wholesale & retail | 2018 |
| AI Fusion Ltd | Information & communication | 2021 |
| AI Guarding Limited | Administrative & support | 2025 |
| AI Nest Solutions Ltd | Information & communication | 2025 |
| AI Shipshape Ltd | Information & communication | 2024 |
| Aible Ltd | Information & communication | 2023 |
| Aidataeng Solutions Limited | Information & communication | 2026 |
| AIG Tech Solution Ltd | Information & communication | 2020 |
| Aignite Ltd | Information & communication | 2024 |
| Aiily&W Ltd | Education | 2014 |
| AIK Properties Ltd | Real estate | 2025 |
| AIM Rentals Limited | Administrative & support | 2019 |
| AIM to Succeed Ltd | Professional & scientific | 2010 |
| Aimee's Happy Tail's Ltd | Agriculture & fishing | 2023 |
| Aimentoring Ltd | Education | 2025 |
| Aims & Objectives Limited | Information & communication | 2018 |
| Aims-G Ltd | Information & communication | 2024 |
| Ainav Ltd | Information & communication | 2025 |
| Aine Investment Group Ltd | Real estate | 2025 |
| Ainka Limited | Construction | 2016 |
| Aintree Management Company Limited | Real estate | 2016 |
| AIP Acquisitions II Limited | Financial services | 2015 |
| AIP Acquisitions III Limited | Financial services | 2016 |
| AIP Acquisitions VI Limited | Financial services | 2019 |
| AIP Holdings 2 Limited | Administrative & support | 2019 |
| AIP Holdings Limited | Financial services | 2014 |
| Air & Marine Products Ltd | Wholesale & retail | 2013 |
| Air Park Parking Ltd | Transport & logistics | 2026 |
| Air Sea Logistics Limited | Transport & logistics | 1996 |
| Airbiz Aviation Strategies Limited | Professional & scientific | 2015 |
| Aircom Aviation Ltd | Professional & scientific | 2026 |
| Airflow Capital Limited | Administrative & support | 2025 |
| Airline Computer Engineering Limited | Professional & scientific | 2001 |
| Airmidpg Limited | Health & social care | 2025 |
| Airplay Aircraft Ltd | Wholesale & retail | 2017 |
| Airport Chauffeurs Reading Limited | Transport & logistics | 2022 |
| Airport Executive Cars Online Ltd | Transport & logistics | 2015 |
| Airport EZ Cars Limited | Transport & logistics | 2009 |
| Airport Travels (Reading) Limited | Transport & logistics | 2015 |
| Airsafe Limited | Extraterritorial | 2000 |
| Airsourceuk Ltd | Professional & scientific | 2019 |
| Airsports Insurance Bureau Limited | Other services | 1993 |
| Airtime Systems Limited | Information & communication | 2012 |
| Airush Technology Limited | Information & communication | 2016 |
| AIS Products Ltd | Wholesale & retail | 2024 |
| AIS Technologies Limited | Information & communication | 2025 |
| Aisha & Babirye Ltd | Health & social care | 2025 |
| Aiso Technology Ltd | Information & communication | 2025 |
| Aissaoui Solutions Limited | Real estate | 2025 |
| AIT Consultancy Services Ltd | Professional & scientific | 2023 |
| Aivhub Ltd | Information & communication | 2016 |
| AJ 77 Ltd | Construction | 2017 |
| AJ Clint Consulting Ltd | Professional & scientific | 2023 |
| AJ Imports & Exports Limited | Wholesale & retail | 2025 |
| AJ Opal Estates Ltd | Real estate | 2015 |
| AJ Sellwood Building Solutions Limited | Construction | 2019 |