| Accountants YOU CAN Talk With Limited | Professional & scientific | 2008 |
| Accounting Firm Acquisition Operations Ltd | Information & communication | 2023 |
| Accountplan Limited | Professional & scientific | 2000 |
| Accounts and Tax Consultancy Limited | Professional & scientific | 2006 |
| Ace Associates (UK) Limited | Professional & scientific | 2005 |
| Ace Properties (London) Ltd | Real estate | 2017 |
| ACM Resources Limited | Administrative & support | 2005 |
| Acorn Specialist Treatments Limited | Wholesale & retail | 1984 |
| Acre Boundary Limited | Real estate | 1995 |
| Acrewoods Limited | Real estate | 2003 |
| Acrocross Limited | Other services | 1989 |
| Acropolis Building Services Limited | Construction | 2008 |
| Acticom Marketing Ltd. | Wholesale & retail | 1994 |
| Action for Learning Limited | Extraterritorial | 2007 |
| Actioncom Limited | Information & communication | 1991 |
| Active Cleaning Contractors Limited | Administrative & support | 2003 |
| Active Freight Management Limited | Transport & logistics | 2005 |
| Active Webdezign Ltd | Information & communication | 2000 |
| Acton Roscommon Axis Limited | Real estate | 2001 |
| Actual Pest Control Limited | Agriculture & fishing | 2006 |
| Acuheal Limited | Health & social care | 2002 |
| Adams and Oliver Trustees Limited | Other services | 2025 |
| Adamya Technologies Ltd | Information & communication | 2021 |
| Adaptive Resilience Limited | Education | 2014 |
| Addari Osseo LAB Limited | Health & social care | 2003 |
| Added Value Accounting (2000) Limited | Other services | 1999 |
| Aden Solutions Limited | Professional & scientific | 2014 |
| Adhvik 672 Ltd | Hospitality | 2024 |
| Adityajaya Trading Limited | Wholesale & retail | 2024 |
| Adjustable Productions Limited | Information & communication | 2006 |
| Adminhurst Limited | Hospitality | 1989 |
| ADR Proffetixx Ltd | Health & social care | 2012 |
| Adswood Properties Limited | Real estate | 2001 |
| Advanced IT Solutions UK Limited | Information & communication | 2005 |
| Advisia Consultants Ltd | Information & communication | 2025 |
| AEA Enterprisers Limited | Wholesale & retail | 2025 |
| AEL Infosys Limited | Information & communication | 2002 |
| Aero Cargo Logistics Limited | Transport & logistics | 2022 |
| AES Propco Limited | Real estate | 2025 |
| AES Properties Holdco Limited | Financial services | 2025 |
| AES Trading Holdco Limited | Financial services | 2025 |
| Aesthetic Plastic Surgery Ltd | Health & social care | 2002 |
| Affinity Accountants Limited | Extraterritorial | 2024 |
| Affinity Associates (Horsham) Limited | Professional & scientific | 2025 |
| Affinity Associates Group Limited | Financial services | 2010 |
| Affinity Associates Outsourcing Limited | Professional & scientific | 2025 |
| Affinity Consulting Limited | Professional & scientific | 2024 |
| Affordable Vehicle Solutions Ltd | Manufacturing | 2022 |
| Afinacorp Limited | Financial services | 1986 |
| Afom Solutions Ltd | Information & communication | 2021 |
| African Education International Limited | Education | 2002 |
| AG Construction Limited | Wholesale & retail | 2005 |
| AG Upvc Centre Limited | Other services | 2006 |
| Agategold Limited | Wholesale & retail | 1990 |
| Aggregate Supplies Limited | Extraterritorial | 2005 |
| Agincourt Trading Limited | Wholesale & retail | 1990 |
| Agnes Road Management Company Limited | Real estate | 2004 |
| AGR Investments Limited | Real estate | 2006 |
| Agrapo Limited | Wholesale & retail | 1974 |
| Agrawal Estate Ltd | Real estate | 2024 |
| AH Empire Limited | Hospitality | 2011 |
| Air BP Limited | Wholesale & retail | 1973 |
| Air Fares Limited | | 1984 |
| Airport Cargo Limited | Transport & logistics | 2001 |
| Airroutes Limited | Administrative & support | 2003 |
| Airworld Tours Limited | Administrative & support | 1998 |
| Aisha Brooks Ltd | Wholesale & retail | 2006 |
| AJ Management Consultants Ltd | Wholesale & retail | 2024 |
| AJ Waterproofing Services Ltd | Construction | 2006 |
| Ajibs Design UK Limited | Professional & scientific | 2000 |
| Ajjt Limited | Administrative & support | 2015 |
| Ajmal Trading Ltd | Wholesale & retail | 2007 |
| AK Services & Solutions Ltd | Administrative & support | 2016 |
| Akay's Investment Limited | Real estate | 2021 |
| AKB Functional Fitness Ltd | Arts & recreation | 2020 |
| AKG Accountants Limited | Professional & scientific | 2004 |
| Akhtar Accountancy Limited | Professional & scientific | 2005 |
| AKR Properties (Hanwell) Limited | Real estate | 2006 |
| Akshar Financial Services Ltd | Financial services | 2006 |
| Akshar Foods Limited | Hospitality | 2017 |
| Akshay Management Services Limited | Professional & scientific | 2002 |
| Aksianmed Ltd | Health & social care | 2019 |
| Aksm Limited | Administrative & support | 2007 |
| AL Rawshi Market Ltd | Hospitality | 2025 |
| Alarms Professionals (UK) Ltd | Administrative & support | 2004 |
| Alba Building Services Ltd | Construction | 2006 |
| Albe (England) Limited | Manufacturing | 1965 |
| Albe (Holdings) Limited | Professional & scientific | 2003 |
| Alenco Properties Limited | Administrative & support | 1972 |
| Alfred Road Limited | Extraterritorial | 1991 |
| Alice Mews Management Company Limited | Other services | 1989 |
| Alidina & Co Limited | Professional & scientific | 2003 |
| ALL Ltd. | Professional & scientific | 1988 |
| ALL Tech Comforts Ltd | Construction | 2016 |
| Allan King Ltd | Information & communication | 2007 |
| Allen Marmot (European) Limited | Manufacturing | 1968 |
| Allglass (West London) Limited | Construction | 2003 |
| Allied Business Contracts Limited | Wholesale & retail | 1997 |
| Allied Finance (UK) Limited | Administrative & support | 2000 |
| Allipharm (UK) Limited | Wholesale & retail | 1994 |