| ABR Garage Doors Ltd | Other services | 2021 |
| Abrah Ltd | Wholesale & retail | 2025 |
| Abri Berry Conseil Ltd | Professional & scientific | 2026 |
| ABS Legal Limited | Professional & scientific | 2020 |
| Absolute Floors & Walls Ltd | Construction | 2012 |
| Absolute Home Development Ltd | Construction | 2020 |
| Absolute Scaffolding Systems Ltd | Construction | 2014 |
| Abundant Life Family Churches Limited | Other services | 1998 |
| AC Cables Limited | Extraterritorial | 1993 |
| AC Holdings PVT Ltd | Administrative & support | 2017 |
| AC Industries Limited | Financial services | 2026 |
| AC Order Ltd | Wholesale & retail | 2025 |
| AC Response Holdings Limited | Financial services | 2021 |
| AC Waywell Construction Limited | Construction | 2020 |
| Academy Central LLP | | 2006 |
| Acarl Ltd | Construction | 2025 |
| Acasa Ltd | Health & social care | 2018 |
| Accado Limited | Information & communication | 2004 |
| Accado Properties Limited | Real estate | 2022 |
| Accado Software Limited | Information & communication | 2004 |
| Accelerate Business Consultancy & Solutions Ltd | Administrative & support | 2022 |
| Accencis Consulting Ltd | Information & communication | 2019 |
| Accencis Property Ltd | Real estate | 2021 |
| Access UK Immigration Ltd | Professional & scientific | 2020 |
| Accident Claims Centre (HW) Ltd | Other services | 2018 |
| Accident Injury Helpline Limited | Administrative & support | 2011 |
| Accident Injury Management Service Ltd | Administrative & support | 2017 |
| Accident Management and Injury Claims Ltd | Administrative & support | 2009 |
| Account-Ed Community CIC | Professional & scientific | 2025 |
| Accountant SHE Ltd | Wholesale & retail | 2021 |
| Accounting BEE Limited | Extraterritorial | 2002 |
| Accounting Software and Services Limited | Extraterritorial | 1994 |
| Accounting Tax Consulting Ltd | Professional & scientific | 2020 |
| Accurate Count Ltd | Professional & scientific | 2024 |
| Accurate Translation Ltd | Professional & scientific | 2025 |
| Accutum Systems Ltd | Information & communication | 2000 |
| ACD Sales & Marketing Consultants Limited | Professional & scientific | 2014 |
| Ace Autos Mart Ltd | Wholesale & retail | 2018 |
| Ace Building Chemicals Limited | Wholesale & retail | 1992 |
| Ace Cabz Ltd | Transport & logistics | 2024 |
| Ace Executive Travel Limited | Transport & logistics | 2024 |
| Ace Minibus Travel Limited | Transport & logistics | 2024 |
| Ace Property & Management (H/W) Limited | Real estate | 1999 |
| Ace Residential Property Lettings Limited | Real estate | 2024 |
| Ace Roofing Contractors Limited | Construction | 2021 |
| Ace Security Services Limited | Administrative & support | 2021 |
| Aces Estate Agents Ltd | Real estate | 2017 |
| Acha Foods Ltd | Hospitality | 2025 |
| Achates Holdings Limited | Financial services | 1992 |
| Achieve Property Bucks Ltd | Real estate | 2026 |
| Ackrack Quartz Limited | Information & communication | 1995 |
| Acls Training Services Limited | Health & social care | 2022 |
| Acme Technologies and Security Solutions Ltd | Wholesale & retail | 2018 |
| Acorn Business Consultants & Advisors Ltd | Financial services | 2025 |
| Acorn Homes Limited | Construction | 1979 |
| Acquatech Limited | Construction | 2007 |
| Across the Waves Massage Ltd | Health & social care | 2024 |
| Acrostak-Uk Limited | Wholesale & retail | 2010 |
| Acta NON Verba Limited | Professional & scientific | 2016 |
| Action for Local Change CIC | Professional & scientific | 2025 |
| Actionstep Limited | Extraterritorial | 2022 |
| Actionstep Operations UK Limited | Information & communication | 2017 |
| Active Electronics PLC | Wholesale & retail | 1980 |
| Active Learning 11 Plus Limited | Education | 2024 |
| Active Mindfulness Ltd | Health & social care | 2025 |
| Acuity Internet Limited | Information & communication | 2003 |
| Acuity Software Limited | Information & communication | 2003 |
| Acuity Software Technologies Limited | Information & communication | 2001 |
| Acuitysecurity.Io Limited | Information & communication | 2022 |
| AD 01 MI Consultancy Ltd. Ltd | Administrative & support | 2010 |
| AD Developments London Limited | Real estate | 2026 |
| AD Mechanics Limited | Wholesale & retail | 2022 |
| AD Multitraders Ltd | Construction | 2026 |
| Adam Ceramics Limited | Construction | 2004 |
| Adam HW Property Limited | Real estate | 2024 |
| Adam Torok Contracting Ltd | Manufacturing | 2026 |
| Adams & Page Limited | Wholesale & retail | 1940 |
| Adamzay Ltd | Professional & scientific | 2021 |
| Adapted Pictures Ltd | Administrative & support | 2017 |
| Adaptive Aerospace Ltd | Manufacturing | 2021 |
| Adaptive Homes Limited | Real estate | 2020 |
| ADB Exterior Cleaning Solutions Ltd | Administrative & support | 2016 |
| Adcal Labels Limited | Manufacturing | 1977 |
| ADD Power Limited | Manufacturing | 2022 |
| Addt Holdings Ltd | Financial services | 2020 |
| Addventure Club Ltd | Health & social care | 2018 |
| Adelphi Events Management Ltd | Arts & recreation | 2012 |
| Ademi Construction Ltd | Construction | 2021 |
| Adeplast Limited | Construction | 2022 |
| Adept Apparel Ltd | Wholesale & retail | 2024 |
| ADF Collectables Limited | Wholesale & retail | 2023 |
| Adhd and Autism Oasis Limited | Health & social care | 2025 |
| Adhere Investments Limited | Real estate | 2014 |
| ADI Carpentry Ltd | Manufacturing | 2022 |
| Adige (UK) Ltd | Wholesale & retail | 2000 |
| Admax Ltd | Construction | 2014 |
| Admiral Developments Limited | Extraterritorial | 1991 |
| Admiral Homes (Eastern) Limited | Extraterritorial | 1967 |
| Admiral Homes Limited | Extraterritorial | 1988 |
| Admired Store Ltd | Wholesale & retail | 2025 |