| Acorn Utilities Limited | Administrative & support | 2010 |
| Acoustic Design & Architecture Ltd | Construction | 2025 |
| Acoustics Noise and Vibration Limited | Wholesale & retail | 1998 |
| ACP Health Care Limited | Public administration | 2022 |
| ACP Heating Ltd | Construction | 2022 |
| ACP Supplies Limited | Wholesale & retail | 2025 |
| ACR Paisa Limited | Hospitality | 2025 |
| ACR Waterslade Limited | Real estate | 2019 |
| Acrebray Limited | Information & communication | 2024 |
| Acres Farm Fenders Limited | Wholesale & retail | 2005 |
| Acron Construction Services Limited | Construction | 2026 |
| Acrylic Pixel Ltd | Manufacturing | 2022 |
| ACS & SON Electrical Services Ltd | Construction | 2018 |
| ACS Interiors Ltd | Construction | 2024 |
| ACS Prime Energy Group Ltd | Construction | 2023 |
| ACS Private Clients Ltd | Financial services | 2019 |
| ACS Smart Consulting Limited | Information & communication | 2015 |
| Acsc Limited | Health & social care | 2007 |
| Acsn Ltd | Financial services | 2019 |
| Action Express Limited | Extraterritorial | 2000 |
| Action Replay Records Limited | Other services | 1983 |
| Action Speaks C.I.C. | Hospitality | 2020 |
| Activado CIC | Arts & recreation | 2026 |
| Active Care Rehab Limited | Health & social care | 2024 |
| Active Cool Ltd | Construction | 2025 |
| Active Design Limited | Manufacturing | 1991 |
| Active Development Solutions Limited | Construction | 2007 |
| Active Financial Ltd | Financial services | 2024 |
| Active Landscapes Limited | Arts & recreation | 2009 |
| Active Life Solutions Ltd. | Wholesale & retail | 2018 |
| Active RMS Ltd | Construction | 2021 |
| Active With Power Limited | Professional & scientific | 2024 |
| Activefixers Ltd | Construction | 2016 |
| Activexchange Ltd | Information & communication | 2020 |
| Activfitgyms Ltd | Arts & recreation | 2024 |
| Activist Group Limited | Administrative & support | 2008 |
| Actopia Communications Limited | Information & communication | 2010 |
| Actora Ltd | Information & communication | 2025 |
| Acumant Ltd | Information & communication | 2022 |
| Acusol Ltd | Professional & scientific | 2018 |
| Acute Ambulance & Medical Services (Training & Events) Ltd | Education | 2009 |
| ACW Property Solutions Limited | Real estate | 2020 |
| AD & AJ Properties Ltd | Real estate | 2026 |
| AD Cube Consulting Limited | Other services | 2017 |
| AD Fulfilments Ltd | Wholesale & retail | 2025 |
| AD Logix Ltd | Information & communication | 2019 |
| AD RAY Private Limited | Real estate | 2025 |
| AD Valorem (AB) Limited | Financial services | 2024 |
| AD Valorem (DK) Limited | Financial services | 2024 |
| AD Valorem (NW) Limited | Financial services | 2024 |
| AD Valorem (SW) Limited | Financial services | 2024 |
| AD Valorem (TF) Limited | Financial services | 2024 |
| AD Valorem (ZA) Limited | Financial services | 2024 |
| AD Valorem Accountancy Services Limited | Professional & scientific | 2001 |
| AD Valorem Audit Services Limited | Professional & scientific | 2009 |
| AD Valorem Company Secretarial Limited | Extraterritorial | 2001 |
| AD Valorem Consulting Limited | Administrative & support | 2000 |
| AD Valorem Corporate Trustees LLP | | 2009 |
| AD Valorem Estate Planning Services Limited | Other services | 2025 |
| AD Valorem Group Limited | Professional & scientific | 2019 |
| AD Valorem Limited | Extraterritorial | 2022 |
| AD Valorem Research and Development Limited | Professional & scientific | 2018 |
| AD Valorem Wealth Management Services Limited | Financial services | 2025 |
| AD Ventures (Milton Keynes) Limited | Other services | 2018 |
| AD Watts Electrical Ltd | Construction | 2021 |
| Ad-Creations Hub Ltd | Wholesale & retail | 2024 |
| ADA Childcare Services Limited | Health & social care | 2024 |
| Adam Accounting Services Ltd | Professional & scientific | 2010 |
| Adam Afro Foods Ltd | Wholesale & retail | 2022 |
| Adam Brundle Catering Limited | Hospitality | 2022 |
| Adam CAM Creative Ltd | Professional & scientific | 2026 |
| Adam Equipment Co. Limited | Manufacturing | 1977 |
| Adam Hutchins Limited | Administrative & support | 2006 |
| Adam J Properties Ltd | Real estate | 2026 |
| Adam Learner Renovations Ltd | Construction | 2019 |
| Adamelie Limited | Real estate | 2014 |
| Adams Automotive Ltd | Wholesale & retail | 2020 |
| Adams Chester Lovell & Co LLP | | 2008 |
| Adams Property Contracts Limited | Construction | 2019 |
| Adam’S Car’S MK Ltd | Wholesale & retail | 2022 |
| Adapt IT Recruitment Limited | Administrative & support | 1999 |
| Adapt IT Support Limited | Administrative & support | 2002 |
| Adapt Recruitment Limited | Professional & scientific | 1999 |
| Adapt Security Ltd | Administrative & support | 2023 |
| Adapt Workforce Limited | Administrative & support | 2003 |
| Adaptifi Limited | Information & communication | 2018 |
| Adaptogenica UK Ltd | Other services | 2025 |
| Adareen Health Limited | Health & social care | 2024 |
| Adas UK Group Ltd | Construction | 2023 |
| Aday Chef Ltd | Hospitality | 2023 |
| Adbols Limited | Professional & scientific | 2018 |
| ADD Consulting Limited | Information & communication | 2016 |
| ADD Property Talent Limited | Administrative & support | 2025 |
| ADD Room Installers Ltd | Construction | 2022 |
| ADD Space Garden Living Ltd | Construction | 2025 |
| Add/Margate Limited | Real estate | 2017 |
| Add/Projects Limited | Professional & scientific | 2019 |
| Add/Uk Limited | Real estate | 2014 |
| Adda Plumbing and GAS Services Ltd | Construction | 2004 |
| Addadas Ltd | Hospitality | 2022 |