| ACA Consultancy Ltd | Professional & scientific | 2024 |
| Academy Design Services Ltd | Professional & scientific | 2004 |
| Academy Investment Co.Limited(The) | Construction | 1959 |
| Academy Live Broadcasting LLP | | 2018 |
| Academy Sports Maintenance Ltd | Construction | 2023 |
| Academy Sports Surfaces Limited | Construction | 2016 |
| Acare Kent Ltd | Health & social care | 2023 |
| ACB Fire Consultancy Limited | Professional & scientific | 2012 |
| ACB Fire Sprinklers Limited | Public administration | 2022 |
| ACC UK Insurance Services Limited | Financial services | 2005 |
| Access Fulfilment Ltd | Other services | 2014 |
| Access Industrial Tyres Ltd | Manufacturing | 2020 |
| Access Scaffolding (South East) Limited | Construction | 2016 |
| Access Scaffolding (South) Limited | Extraterritorial | 2016 |
| Access Staffing Ltd | Health & social care | 2022 |
| Accessible Outdoors Ltd | Wholesale & retail | 2026 |
| Accessible Plumbing Solutions Ltd | Manufacturing | 2025 |
| Accommshop Limited | Real estate | 2003 |
| Accountancy & Finance Recruitment Limited | Professional & scientific | 1996 |
| Accounts and Taxation Limited | Professional & scientific | 2011 |
| Accura Moulding Limited | Manufacturing | 2018 |
| Accuro Wellbeing Limited | Health & social care | 2020 |
| Ace Car Conversions Limited | Administrative & support | 2003 |
| Ace Cornerstone Limited | Real estate | 2022 |
| Ace DRY Cleaning Limited | Other services | 2020 |
| Ace Learning | Education | 2013 |
| Ace Marketing Group Ltd | Professional & scientific | 2025 |
| Ace Movements Transport Limited | Transport & logistics | 2007 |
| Ace Pointing Specialists Ltd | Construction | 2006 |
| Ace Sectional Buildings Limited | Manufacturing | 2001 |
| Ace Sprinklers Limited | Construction | 2022 |
| Acepoint Services Limited | Information & communication | 2016 |
| Aces UK Properties Ltd | Real estate | 2019 |
| Ackerman Property Group Limited | Financial services | 2024 |
| ACL01 Limited | Wholesale & retail | 2024 |
| Aclad FM Consultancy Ltd | Professional & scientific | 2019 |
| Acorn Carpentry and Building Limited | Construction | 2008 |
| Acorn Properties Limited | Real estate | 2025 |
| Acoustiblok UK Limited | Administrative & support | 2003 |
| Acoustic Cloud Limited | Administrative & support | 2011 |
| ACR Business Limited | Wholesale & retail | 2024 |
| Acropolis Construction Management Ltd | Construction | 2018 |
| Action Carpets (Holdings) Limited | Professional & scientific | 2016 |
| Action Carpets Limited | Construction | 2004 |
| Action Incorporated Ltd | Administrative & support | 2022 |
| Action Technical Services and Contracting UK Limited | Construction | 2020 |
| Actiongovern Limited | Manufacturing | 1996 |
| Activ Cycles Limited | Wholesale & retail | 2004 |
| Activated Coaching Limited | Health & social care | 2026 |
| Active C & P Holdings Limited | Professional & scientific | 2012 |
| Active Civil Engineering Limited | Administrative & support | 2009 |
| Active Financial Introductions Ltd | Financial services | 2017 |
| Active Fire Solutions Limited | Public administration | 2010 |
| Active Plant Hire Limited | Construction | 2005 |
| Active Property Limited | Real estate | 2017 |
| Active Residential Property LLP | | 2020 |
| Active Tankers Ltd | Transport & logistics | 2024 |
| Activin LLP | | 2011 |
| Actual Recruitment Services Limited | Professional & scientific | 1998 |
| Acumen Surveying Management Services Limited | Professional & scientific | 2012 |
| Acute Accountants and Business Advisors Ltd | Professional & scientific | 2016 |
| Acute Business Consultants Ltd | Professional & scientific | 2020 |
| ACW Surveying Services Ltd. | Construction | 2011 |
| AD Coelum Consultants Limited | Financial services | 2016 |
| AD Pink Electrical Ltd | Construction | 2015 |
| Adam Ambrose Plumbing & Heating Ltd | Construction | 2025 |
| Adam Brooks Ltd | Health & social care | 2009 |
| Adanash Limited | Administrative & support | 1997 |
| Adans Solutions Ltd | Information & communication | 2025 |
| Adapt Services Group Ltd | Construction | 2026 |
| Adaptations MW Limited | Construction | 2009 |
| ADB Electrical Contractors Ltd | Construction | 2017 |
| ADD Capital Limited | Professional & scientific | 2022 |
| ADD Glow Limited | Wholesale & retail | 2017 |
| ADD M3 for Property Investment and Management Ltd | Real estate | 2019 |
| Add-Tech Testing Services Limited | Professional & scientific | 2026 |
| Addington Leisure Limited | Real estate | 2022 |
| ADE and Tola Ltd | Health & social care | 2025 |
| Adefem Limited | Other services | 2025 |
| Adelaide Consultancy Ltd | Professional & scientific | 2025 |
| Aden Electronics (Holdings) Limited | Financial services | 1997 |
| Aden Electronics Limited | Manufacturing | 1989 |
| Adept Acoustics Limited | Construction | 2023 |
| Adept Management Group Ltd | Professional & scientific | 2004 |
| Adept Refrigeration Limited | Construction | 2021 |
| Adeyeri Lawson Global Organisation Ltd | Health & social care | 2025 |
| Adfg Limited | Real estate | 2019 |
| ADH Estate Agency Limited | Real estate | 2014 |
| Adhdsmart Neurodiversity C.I.C. | Education | 2025 |
| Adhishtam Limited | Wholesale & retail | 2022 |
| Adino Capital Limited | Financial services | 2023 |
| Adjacent Property Holdings Ltd | Real estate | 2016 |
| Adjustoform Products Limited | Manufacturing | 1967 |
| Adlines Limited | Administrative & support | 1991 |
| Adlington Barnstaple Limited | Wholesale & retail | 2016 |
| Administration Associates Limited | Administrative & support | 2015 |
| Admiral Developments (Southern) Limited | Construction | 2006 |
| Admiral Developments Property Letting Limited | Professional & scientific | 2013 |
| Adonko Bitters (UK) Ltd | Wholesale & retail | 2019 |
| Adornment Archive LLP | | 2017 |