| A.D.C. Properties (Loughborough) Limited | Real estate | 1994 |
| A.E.C. Partnership Limited | Professional & scientific | 1984 |
| A.E.P Wastewater Ltd | Other services | 2024 |
| A.G.Wright(Assessors)Limited | Financial services | 1961 |
| A.J. Carter Ltd. | Construction | 2011 |
| A.P. Crawley (Properties) Limited | Real estate | 1978 |
| A.S.A. Swimming Enterprises Limited | Transport & logistics | 1982 |
| A1 Ace Transport Services Ltd. | Other services | 2008 |
| A13 Decorating Ltd | Construction | 2025 |
| A2 Ecommerce Solutions Limited | Wholesale & retail | 2026 |
| A2H Properties Ltd | Real estate | 2019 |
| A2Z Fasteners Limited | Wholesale & retail | 2020 |
| A6 Training and Consultancy Ltd | Education | 2006 |
| AA Aviation Limited | Transport & logistics | 2025 |
| AA Best Solutions 1 Limited | Wholesale & retail | 2025 |
| AA Best Solutions Ltd | Wholesale & retail | 2014 |
| AA Wristbands Ltd | Wholesale & retail | 2014 |
| AAA Oriental Limited | Wholesale & retail | 2017 |
| AAA Window & Door Ltd | Construction | 2026 |
| Aarogyam (UK) CIC | Information & communication | 2020 |
| AB Steel Services Limited | Construction | 2015 |
| AB Test Consultancy Ltd | Information & communication | 2017 |
| Abacus Flooring Solutions Limited | Construction | 2020 |
| Abaplas Materials Ltd | Manufacturing | 2022 |
| Abbacas Consulting Limited | Professional & scientific | 2006 |
| Abbey Hm-Jn Ltd | Financial services | 2024 |
| Abbey Park Motor Spares Limited | Wholesale & retail | 1978 |
| Abell Building Services Ltd | Construction | 2014 |
| Abell Jones Ltd | Real estate | 2024 |
| Abest Financial Services Ltd | Wholesale & retail | 2023 |
| Abisa Limited | Administrative & support | 2021 |
| ABJ Homes Ltd | Construction | 2025 |
| Able Engineering (Midlands) Limited | Manufacturing | 2001 |
| Abmm Limited | Manufacturing | 2013 |
| Abok Limited | Hospitality | 2023 |
| Above and Beyond Complete Renovations Ltd | Administrative & support | 2025 |
| Absolute Care Agency (EM) Limited | Health & social care | 2012 |
| Absolute Design Print Limited | Manufacturing | 2013 |
| Absolute Solar Holdings Limited | Financial services | 2025 |
| Absorbopak Limited | Professional & scientific | 2013 |
| Absorbopak UK Limited | Professional & scientific | 2013 |
| Abstract Consulting Ltd | Other services | 2009 |
| Abzk Limited | Hospitality | 2024 |
| AC Newco Limited | Financial services | 2023 |
| AC Pipefitting Limited | Construction | 2005 |
| AC Utility Services Ltd | Professional & scientific | 2026 |
| AC360 Ltd | Financial services | 2025 |
| ACC Building & Joinery Limited | Construction | 2017 |
| Accelerated Outcomes Ltd | Information & communication | 2023 |
| Acceleweb Ltd | Information & communication | 2019 |
| Access 2 Languages Limited | Professional & scientific | 2013 |
| Access Accounting Limited | Professional & scientific | 2009 |
| Access AUD Ltd | Financial services | 2021 |
| Access Overseas Company Holdings Limited | Financial services | 2018 |
| Access Paysuite Ltd | Financial services | 2002 |
| Access Technology Group Limited | Professional & scientific | 2005 |
| Access UK Ltd | Information & communication | 1989 |
| Access USD Ltd | Financial services | 2022 |
| Accro Limited | Real estate | 1997 |
| Ace Damp Proofing Limited | Construction | 2021 |
| Ace Fire (Midlands) Limited | Professional & scientific | 1999 |
| Ace Nexus Limited | Wholesale & retail | 2026 |
| Ace-Uk Services Ltd | Other services | 2023 |
| Acer Bookkeeping Support Limited | Professional & scientific | 2009 |
| Acer Homes Ltd | Real estate | 2022 |
| Aceso Pathway Limited | Professional & scientific | 2025 |
| ACG Legal Marketing Ltd | Other services | 2025 |
| Acorn (2020) Limited | Real estate | 2020 |
| Acorn Recyclers (Property) Limited | Financial services | 2025 |
| Acorn Recyclers Limited | Water & waste | 2003 |
| Acorn Screen Products Limited | Manufacturing | 1988 |
| ACORN7 Ltd | Professional & scientific | 2022 |
| ACP Services (Midlands) Ltd | Construction | 2025 |
| ACS Environmental Limited | Construction | 2008 |
| ACT Medical Ltd | Professional & scientific | 2021 |
| Actbronze Limited | Manufacturing | 1984 |
| Active Aims Limited | Other services | 2002 |
| Active Mind Studio Ltd | Information & communication | 2025 |
| Active Motion Physiotherapy Limited | Health & social care | 2025 |
| Active Partnerships | Arts & recreation | 2011 |
| Active Remedial Solutions Limited | Extraterritorial | 1998 |
| Actprop Ltd | Real estate | 2025 |
| Acturis Investments Ltd | Hospitality | 2023 |
| Acutaas Healthcare Limited | Manufacturing | 2026 |
| Acutefx Design Ltd | Information & communication | 2008 |
| AD Astra Exports Ltd | Wholesale & retail | 2018 |
| AD Hardesty Ltd | Real estate | 2026 |
| Adam James Consulting Ltd | Professional & scientific | 2018 |
| Adam Patel Optometry Limited | Health & social care | 2017 |
| Adams Cars Sales Ltd | Wholesale & retail | 2016 |
| Adams Cars Shepshed Ltd | Wholesale & retail | 2025 |
| Adams Industrial Doors Ltd | Construction | 2017 |
| Adana Barbers Ltd | Other services | 2018 |
| ADC Developments Limited | Real estate | 2002 |
| Adco Projects Ltd | Real estate | 2022 |
| Adept Workplace Solutions Limited | Manufacturing | 1996 |
| Adey Holdings Limited | Professional & scientific | 2002 |
| Adey Steel Limited | Manufacturing | 1989 |
| Adey Steelshop Ltd. | Manufacturing | 1993 |
| Adey Technical Ltd. | Professional & scientific | 2011 |