| ACJ Aluminium Manufacturing & Maintenance Ltd | Manufacturing | 2023 |
| Acorn Florists Limited | Wholesale & retail | 2013 |
| Acraman (650) Limited | Wholesale & retail | 2019 |
| Acre Business Consultancy Limited | Administrative & support | 2019 |
| Action Adventure Pursuits Limited | Administrative & support | 2024 |
| Active 8 Electrical Solutions Limited | Construction | 2006 |
| Active Achievement Limited | Education | 2024 |
| AD and C Electrical Services Ltd | Manufacturing | 2013 |
| ADA Communications Ltd | Construction | 2024 |
| Adam Bryant Golf Ltd | Arts & recreation | 2023 |
| Adam Jones Bespoke Interiors Limited | Construction | 2025 |
| Adam the Van MAN Limited | Wholesale & retail | 2025 |
| Adam's Norton Ltd | Hospitality | 2026 |
| Adamas Aesthetics Limited | Other services | 2024 |
| Adapt Construction Ltd | Construction | 2023 |
| Addfield Limited | Manufacturing | 2014 |
| ADF Scale (Holdings) Limited | Administrative & support | 2019 |
| Adha Properties Ltd | Real estate | 2025 |
| Adhd Pirates CIC | Health & social care | 2023 |
| Adrian Mark Jackson Ltd | Extraterritorial | 2023 |
| Advance Factors (UK) Ltd | Financial services | 2025 |
| Advanced Concrete Cutting Limited | Construction | 2016 |
| Advanced Cooling (UK) Limited | Construction | 2006 |
| Advanced Driveways (Northants) Ltd | Administrative & support | 2023 |
| Advanced Driving Services Limited | Transport & logistics | 2014 |
| Advanced Electrical (Midlands) Ltd | Construction | 2012 |
| Advanced Glazing Installations Limited | Construction | 2021 |
| Advanced Properties and Lettings Ltd | Real estate | 2017 |
| Advantage Construction (Midlands) Ltd | Construction | 2024 |
| Advantage Holdings (Midlands) Limited | Financial services | 2025 |
| Advantage Retirement Homes (East) Ltd | Health & social care | 2025 |
| Advantage Retirement Homes (GB) Ltd | Health & social care | 2023 |
| Advantage Retirement Homes (NW) Limited | Health & social care | 2025 |
| Advantage Retirement Homes (UK) Ltd | Health & social care | 2023 |
| Advantage Retirement Homes(Mids) Ltd | Health & social care | 2026 |
| Adventurex Conferences C.I.C. | Administrative & support | 2023 |
| Advisory International Limited | Professional & scientific | 2026 |
| AE Digital Ltd | Wholesale & retail | 2025 |
| Aegis Projects Ltd | Real estate | 2026 |
| AEH Construction Limited | Construction | 2012 |
| Aemh Ltd | Wholesale & retail | 2024 |
| Aerial Promotions Limited | Transport & logistics | 1988 |
| Aesthetikay Ltd | Health & social care | 2020 |
| AF Financial Consultants Ltd | Financial services | 2019 |
| Af-Mok Performance Ltd | Wholesale & retail | 2022 |
| Affirmative Action (U.K.) Limited | Professional & scientific | 1982 |
| Affordable Cars 2U Ltd | Wholesale & retail | 2023 |
| Affy Homes Limited | Real estate | 2024 |
| Aftec Electrical Services Limited | Construction | 2001 |
| AG Chiro Limited | Health & social care | 2019 |
| Agency 4 Work Limited | Administrative & support | 2021 |
| Aggrandise VA Ltd | Administrative & support | 2018 |
| Aggreko Employment Services Limited | Administrative & support | 2020 |
| Aggreko IPP Solutions Development Limited | Financial services | 2024 |
| Aggreko IPP Solutions Europe Limited | Financial services | 2024 |
| Aggreko RAY SA Limited | Professional & scientific | 2023 |
| Aggreko RAY SA Midco Limited | Financial services | 2024 |
| Aggreko RAY UK Limited | Professional & scientific | 2023 |
| Aggreko Resalta Midco Limited | Financial services | 2025 |
| Agies Childrens Services Limited | Health & social care | 2025 |
| Agiliti Group Ltd | Administrative & support | 2016 |
| AGJ Carpentry Services Limited | Construction | 2024 |
| AGM 1960 Trading Company Limited | Information & communication | 2008 |
| AH Building and Renovation Limited | Construction | 2025 |
| AH Holdings and Investments Limited | Financial services | 2019 |
| Ahmed J Holdings Ltd | Real estate | 2021 |
| AI Body Works Limited | Wholesale & retail | 2021 |
| AIM HI Investments Ltd | Financial services | 2015 |
| AIM HI Transport Ltd | Other services | 1998 |
| AIN Care Ltd | Professional & scientific | 2019 |
| Aintellence Ltd | Information & communication | 2025 |
| Air Alliance Ltd | Professional & scientific | 2009 |
| Air Care Compressors Limited | Wholesale & retail | 1999 |
| Air Compressor Management Ltd. | Manufacturing | 2009 |
| Air, Vacuum and Blowers Ltd | Wholesale & retail | 2024 |
| Airconstruct (Contracts) Ltd | Construction | 2014 |
| Airconstruct (Management) Ltd | Professional & scientific | 2011 |
| Airtek Automotive Ltd | Wholesale & retail | 2021 |
| Airtest Ltd | Professional & scientific | 2016 |
| Airwake Ltd | Arts & recreation | 2019 |
| Aiy-Services Ltd | Administrative & support | 2018 |
| AJ Autos (Cannock) Limited | Wholesale & retail | 2021 |
| AJ Bacon Carpenters Limited | Construction | 2015 |
| AJ Davies Advisory Limited | Professional & scientific | 2026 |
| AJL Respiratory and Sleep Services Limited | Health & social care | 2025 |
| AJM Contracting Ltd | Professional & scientific | 2026 |
| AJR Drinks Ltd | Wholesale & retail | 2015 |
| AJT Construction Midlands Ltd | Construction | 2023 |
| AJW Build Ltd | Construction | 2025 |
| AK Property Innovations Limited | Real estate | 2022 |
| Akan Cleaning Services Limited | Administrative & support | 2020 |
| AKR Property Rental Limited | Real estate | 2018 |
| Alan Henderson Racing Ltd | Wholesale & retail | 2011 |
| Alax's Properties Ltd | Real estate | 2020 |
| Albion Acquisitions Limited | Financial services | 2021 |
| Albion Holdco Limited | Financial services | 2021 |
| Albion Midco Limited | Financial services | 2021 |
| Albion Topco Limited | Financial services | 2021 |
| Albrighton Care Limited | Health & social care | 2013 |
| Albrighton Holdings & Investments Limited | Real estate | 2019 |