| A Star Property Group Ltd | Real estate | 2021 |
| A Vision Creates Limited | Other services | 2023 |
| A&A Organisation Limited | Wholesale & retail | 2018 |
| A&B Clinicals Ltd | Health & social care | 2025 |
| A&B UK Properties Ltd | Real estate | 2022 |
| A&C Plastering Limited | Construction | 2012 |
| A&I Property Group Limited | Administrative & support | 2016 |
| A&J Churchill Limited | Construction | 2017 |
| A. Norris Electrical Limited | Extraterritorial | 2005 |
| A.G. Axton & Sons (Wholesale) Limited | Wholesale & retail | 2003 |
| A.G. Axton Warehousing Limited | Transport & logistics | 1986 |
| A.H.Mason Flooring Limited | Construction | 2019 |
| A.V Fire & Security Ltd | Administrative & support | 2025 |
| A.W. Jeffreys (Southampton) Limited | Manufacturing | 1995 |
| A1 Body Technical Limited | Wholesale & retail | 2022 |
| A1 Forward (of) Limited | Professional & scientific | 2019 |
| A1 Forward Limited | Financial services | 2019 |
| A1 Forward Property Limited | Real estate | 2020 |
| A1 Powder Coatings Limited | Construction | 2003 |
| A2B Drive Ltd | Transport & logistics | 2026 |
| A2B Express Travel Limited | Professional & scientific | 2003 |
| A2B Travel Solutions Ltd | Transport & logistics | 2025 |
| AA Construction (Southern) Ltd | Construction | 2016 |
| AA Fencing Hampshire Ltd | Construction | 2022 |
| AA Motor Solutions Ltd | Wholesale & retail | 2021 |
| AA Property Matters Ltd | Real estate | 2022 |
| AA Sales Ltd | Wholesale & retail | 2024 |
| AA Technologies Ltd | Information & communication | 2022 |
| Aaai Visionaries Ltd | Wholesale & retail | 2025 |
| Aarogya Healthcare Limited | Wholesale & retail | 2023 |
| Aarpeez Flooring Ltd | Construction | 2015 |
| Aart Lettings Limited | Real estate | 2026 |
| Aathis Kudil Limited | Real estate | 2025 |
| AB Infotech Limited | Information & communication | 2011 |
| AB Management & Maintenance Limited | Construction | 2024 |
| AB Roofing Ltd | Construction | 2019 |
| Abbey Asphalt Roofing Limited | Construction | 2015 |
| Abbey Barn South Residents Management Limited | Households | 2019 |
| Abbey Fixings Ltd | Wholesale & retail | 2019 |
| Abbey Heat Transfer Limited | Professional & scientific | 1983 |
| ABC Studios Ltd | Professional & scientific | 2014 |
| Abdn Properties Limited | Real estate | 2023 |
| Abeciou Limited | Administrative & support | 2008 |
| Aberdare Cables | Professional & scientific | 1950 |
| ABL Projects Ltd | Construction | 2018 |
| ABL Ventures Ltd | Financial services | 2026 |
| Able (South) Ltd | Construction | 2008 |
| ABP Project Management Limited | Construction | 2001 |
| Abridge Academy Ltd | Education | 2020 |
| ABS Housing Ltd | Real estate | 2023 |
| ABS South Coast Limited | Other services | 2025 |
| Absolute Board Co. Limited | Wholesale & retail | 2012 |
| Absolute Multisport Ltd | Education | 2022 |
| Abstract Academia Ltd | Education | 2018 |
| Abstract Franchises Limited | Administrative & support | 2023 |
| Abtec Specialist Projects Ltd | Manufacturing | 2011 |
| AC Consultancy & Solutions Ltd | Professional & scientific | 2025 |
| AC Landscapes South Limited | Administrative & support | 2025 |
| ACB Property Maintenance Services Limited | Construction | 2025 |
| ACC Hair & Beauty Limited | Other services | 2018 |
| Accelerate 42 Ltd | Financial services | 2026 |
| Accelerated IOT Systems Ltd | Manufacturing | 2020 |
| Accord Accountants - Chandlers Ford Limited | Professional & scientific | 2002 |
| Accord Community Events Limited | Information & communication | 2019 |
| Account-Ability-(Uk) Limited | Professional & scientific | 2008 |
| Accountants Partnership LLP | | 2007 |
| Accounting Innovations Limited | Professional & scientific | 2005 |
| Accrue Training Limited | Education | 2012 |
| Ace Care Consultancy Ltd | Professional & scientific | 2022 |
| Acethetic Clinics Ltd | Other services | 2026 |
| Acew Limited | Professional & scientific | 2015 |
| Achievesphere Limited | Wholesale & retail | 2024 |
| ACJ Salons Limited | Other services | 2019 |
| Acknowledge Solutions Limited | Construction | 2006 |
| Aclass Kitchens and Carpentry Ltd | Construction | 2014 |
| Acorn Design & Project Management Limited | Construction | 2008 |
| Acoufelt Ltd | Construction | 2021 |
| Acpowertech Ltd | Construction | 2007 |
| Action 2 Results Limited | Professional & scientific | 2006 |
| Action for Lifelong Learning Limited | Extraterritorial | 2007 |
| Action Window Cleaning Ltd | Administrative & support | 2017 |
| Active Roof Repairs Ltd | Construction | 2025 |
| Active Roofing and Cladding Ltd | Construction | 2025 |
| Activexplorers Ltd | Education | 2023 |
| Acunova Solutions Ltd | Information & communication | 2025 |
| Adam Clarke Fencing Ltd | Administrative & support | 2021 |
| Adam Collier Electrical Limited | Construction | 2019 |
| Adam Hurst Construction Limited | Construction | 2019 |
| Adam James Bristow Holdings Ltd | Financial services | 2021 |
| Adam Scott Roofing & Building Ltd | Construction | 2021 |
| Adams Building Services (Southern) Ltd | Construction | 2013 |
| Adams Engineering UK Limited | Professional & scientific | 2002 |
| Adams Wholesale Hampshire Ltd | Wholesale & retail | 2024 |
| Adapt Landscape Construction Ltd | Construction | 2014 |
| Adaptive Reliable Management Systems Ltd | Information & communication | 2012 |
| Adawhite Chilaka Care Solution Limited | Health & social care | 2026 |
| Adel and Agila Oral Surgery Limited | Health & social care | 2024 |
| Adel Medics (Manchester) Ltd | Health & social care | 2018 |
| Adem's Chef Limited | Hospitality | 2019 |
| Adesso Cafe Limited | Wholesale & retail | 2010 |