| Ahead Partnership Limited | Administrative & support | 2006 |
| Ahern Ventures Ltd | Professional & scientific | 2018 |
| Ahjussi Kitchen Ltd | Hospitality | 2026 |
| AHL Connect Limited | Administrative & support | 2014 |
| AHL Holdings (Manchester) Limited | Construction | 2003 |
| AHL Holdings (Wakefield) Limited | Administrative & support | 2002 |
| AHL International Ltd | Professional & scientific | 2026 |
| Ahlain Limited | Real estate | 2024 |
| Ahlussunnah Halaal Certification Authority Ltd | Hospitality | 2023 |
| AHM Carpets Limited | Wholesale & retail | 2023 |
| AHM Property Management (Leeds) Limited | Real estate | 2024 |
| Ahmad ALI Catering Ltd | Hospitality | 2025 |
| Ahmad Meats Ltd | Wholesale & retail | 2019 |
| Ahmadou Ltd | Transport & logistics | 2025 |
| Ahmalik Ltd | Other services | 2025 |
| Ahmed Invested Limited | Financial services | 2022 |
| AHN Choi Ltd | Real estate | 2022 |
| Ahnd Capital Ltd | Real estate | 2020 |
| AHR Fast Food Ltd | Hospitality | 2025 |
| AHR IT Support Ltd | Information & communication | 2025 |
| AHR Properties Ltd | Real estate | 2019 |
| AHS Holdings Limited | Wholesale & retail | 2003 |
| AHS Store Ltd | Wholesale & retail | 2020 |
| AHS1 Tensae Ltd | Wholesale & retail | 2026 |
| Ahsh Group Limited | Financial services | 2026 |
| AHT Group LLP | | 2017 |
| AHT Healthcare Ltd | Manufacturing | 2020 |
| AHT Holdings Ltd | Manufacturing | 2019 |
| Ahura Properties Ltd | Real estate | 2018 |
| AI Actuarial Limited | Financial services | 2021 |
| AI Automation Systems Ltd | Administrative & support | 2021 |
| AI Caesar's Kitchen Ltd | Hospitality | 2026 |
| AI Citizen Limited | Education | 2026 |
| AI COE Limited | Information & communication | 2020 |
| AI Drive International Ltd | Manufacturing | 2026 |
| AI Dynamics Support Ltd | Information & communication | 2025 |
| AI Fitness Ltd | Information & communication | 2023 |
| AI Genie Assist Ltd | Information & communication | 2024 |
| AI Gym Limited | Arts & recreation | 2026 |
| AI Medical Limited | Health & social care | 2015 |
| AI Software Consultancy Services Ltd | Information & communication | 2025 |
| AI Solutions Property Experts Ltd | Real estate | 2024 |
| AI Talent Hub Ltd | Information & communication | 2025 |
| AI Technical Data Limited | Administrative & support | 2020 |
| AI Web Ltd | Information & communication | 2020 |
| Ai-Infusion Consultancy Limited | Information & communication | 2024 |
| AIA Advisory Limited | Other services | 2011 |
| AIA Cars Ltd | Transport & logistics | 2026 |
| AIB (K) Limited | Financial services | 1988 |
| AIB (L) Limited | Financial services | 2021 |
| AIB Pharma Ltd | Health & social care | 2025 |
| Aibo Recruitment Ltd | Administrative & support | 2023 |
| AID Workers Logistics Limited | Transport & logistics | 2022 |
| AID2YOU Healthcare Ltd | Health & social care | 2018 |
| Aida Architecture Ltd | Professional & scientific | 2018 |
| Aida Management Limited | Professional & scientific | 2014 |
| Aida Productions Ltd | Professional & scientific | 2024 |
| Aidan Metcalfe Ltd | Information & communication | 2025 |
| AIE Networks Limited | Information & communication | 2023 |
| Aieco Athleisure Collective Ltd. | Wholesale & retail | 2023 |
| AIF 1 Ltd | Professional & scientific | 2016 |
| Aifrost Ltd | Professional & scientific | 2023 |
| AIG Group Support Limited | Professional & scientific | 2022 |
| AIG Solutions Ltd | Administrative & support | 2022 |
| Aiga Network Ltd | Professional & scientific | 2025 |
| AIK Fragrance Ltd | Wholesale & retail | 2023 |
| AIK Marketing Ltd | Professional & scientific | 2023 |
| AIM 2 Learn Ltd | Administrative & support | 2011 |
| AIM Autos Limited | Wholesale & retail | 2022 |
| AIM Contracts SW Ltd | Construction | 2023 |
| AIM Debt Recovery Ltd | Professional & scientific | 2018 |
| AIM Delivery & Removals Ltd | Transport & logistics | 2020 |
| AIM Excellence Ltd | Hospitality | 2022 |
| AIM Forward Ltd | Professional & scientific | 2023 |
| AIM Greatness Ltd | Hospitality | 2024 |
| AIM Higher Healthcare Limited | Health & social care | 2021 |
| AIM Interiors Limited | Construction | 2019 |
| AIM Quality Ltd | Hospitality | 2022 |
| Aimec Services Ltd | Wholesale & retail | 2019 |
| Aimee Akbar Limited | Wholesale & retail | 2020 |
| Aimg Properties Limited | Real estate | 2020 |
| Aino Ltd | Real estate | 2020 |
| Ainscope Ltd | Wholesale & retail | 2025 |
| Ainsleys of Leeds Limited | Manufacturing | 2010 |
| Ainsty Limited | Financial services | 2021 |
| Ainsworth Technology Limited | Information & communication | 2011 |
| Aintree Associates Ltd. | Administrative & support | 2019 |
| Aintree Hotel Limited | Hospitality | 1994 |
| AIO Partners Ltd | Professional & scientific | 2013 |
| AIO VET Limited | Professional & scientific | 2023 |
| AIP Property Development Ltd | Real estate | 2022 |
| Air BNG Limited | Real estate | 2022 |
| Air Consultants (Leeds) Ltd | Manufacturing | 2024 |
| Air Demand Ltd | Wholesale & retail | 2025 |
| Air Force Properties Limited | Real estate | 2021 |
| Air Force Property Group Ltd | Real estate | 2025 |
| Air Furness Limited | | 1983 |
| Air Kilroe Limited | Transport & logistics | 1995 |
| Air Marine Spares Limited | Wholesale & retail | 2014 |
| Air Services Limited | Manufacturing | 1972 |