| A E L Properties (London) Limited | Extraterritorial | 1998 |
| A E L Properties (Southern) Limited | Real estate | 1998 |
| A H Sealants Ltd | Construction | 2022 |
| A Hammond Heating & Plumbing Ltd | Construction | 2024 |
| A Handmade's Tale Ltd | Wholesale & retail | 2025 |
| A J Neary Limited | Agriculture & fishing | 2013 |
| A L Sporting Ltd | Arts & recreation | 2020 |
| A Life More Organised Ltd | Other services | 2022 |
| A M Carpentry and Construction Ltd | Extraterritorial | 2022 |
| A M Stewart Anaesthesia Limited | Health & social care | 2019 |
| A Medley Risk Consultancy Ltd | Professional & scientific | 2015 |
| A Networks Media Ltd | Information & communication | 2024 |
| A Peagreen Company Limited | Information & communication | 2001 |
| A S M Music Ltd | Education | 2015 |
| A Swift Consulting Ltd | Other services | 2019 |
| A Table for Two Ltd | Information & communication | 2025 |
| A Turing Limited | Information & communication | 2024 |
| A V Cottle Limited | Professional & scientific | 2023 |
| A&G Partners Limited | Professional & scientific | 2021 |
| A&Sd Ltd | Real estate | 2018 |
| A'S & Zees Ltd | Wholesale & retail | 2026 |
| A-Plus Electrical Systems Limited | Construction | 2017 |
| A.D. Maclean Tree Management Ltd | Administrative & support | 2011 |
| A.D.Properties Limited | Construction | 1957 |
| A.R.D International Limited | Wholesale & retail | 2025 |
| A1 Innovation Ltd | Professional & scientific | 2023 |
| A44 Tyre Shop Limited | Extraterritorial | 2014 |
| Aardvark Appliances Ltd | Wholesale & retail | 2006 |
| Aardvarka Research Limited | Information & communication | 2012 |
| Aarlo Designs Limited | Professional & scientific | 2010 |
| AAT Futuretech Ltd | Information & communication | 2025 |
| AB Africa Limited | Construction | 2022 |
| Abaco Estates Limited | Real estate | 1992 |
| Abacus FX Limited | Financial services | 2018 |
| Abbotswood Holdings Limited | Administrative & support | 2024 |
| Abbotts Barton Community Group CIC | Other services | 2026 |
| Abbotts Court Mews Limited | Households | 2010 |
| ABC Media Ltd | Information & communication | 2024 |
| ABD Contracts Ltd | Construction | 2022 |
| Abeona Auto Services Ltd | Wholesale & retail | 2022 |
| ABJ Minimix Limited | Wholesale & retail | 2004 |
| ABJ Transport Limited | Transport & logistics | 2002 |
| Abora Properties Limited | Real estate | 1988 |
| Abouyoussef Ltd | Hospitality | 2025 |
| Absolute Marine Ltd | Manufacturing | 2024 |
| ABZ Consultancy Ltd | Professional & scientific | 2014 |
| AC Custom Coatings Limited | Extraterritorial | 2012 |
| ACA Interactive Solutions Limited | Information & communication | 2014 |
| ACB Europe Limited | Information & communication | 2012 |
| ACC Aero Limited | Manufacturing | 2019 |
| Access Agriculture Limited | Agriculture & fishing | 2020 |
| Accutek Ltd | Wholesale & retail | 2014 |
| Ace Bluejay Ltd | Professional & scientific | 2014 |
| Ace Dorset Downs Limited | Agriculture & fishing | 2023 |
| Ace of Diamonds London Ltd | Hospitality | 2020 |
| Ace Storage Limited | Financial services | 2025 |
| Acer Machinery Solutions Ltd | Wholesale & retail | 2020 |
| Achilles Sport and Leisure Ltd | Construction | 2019 |
| Achimenes Limited | Wholesale & retail | 2010 |
| ACJ Credit Management Ltd | Administrative & support | 2003 |
| Ackenders Ltd | Wholesale & retail | 2023 |
| Acorn Holiday Cottages Limited | Hospitality | 2016 |
| Acorn Shooting Limited | Education | 2020 |
| Acorn Strategic Partnership Ltd | Professional & scientific | 2020 |
| Acrobat Ltd | Professional & scientific | 2015 |
| ACS General Partner Limited | Administrative & support | 2013 |
| Active Navigation Limited | Professional & scientific | 2011 |
| Adactia Consulting Limited | Professional & scientific | 2021 |
| Adair (Winchester) Limited | Real estate | 2018 |
| Adam and Annalisa.Love Limited | Education | 2023 |
| Adam Architecture (International) Limited | Extraterritorial | 1988 |
| Adam Architecture Limited | Professional & scientific | 1986 |
| Adam Follon Master Thatcher Ltd | Other services | 2012 |
| Adam Knibb Architects Ltd | Professional & scientific | 2015 |
| Adam Knibb Interiors Ltd | Other services | 2024 |
| Adams Hendry Consulting Limited | Administrative & support | 1999 |
| Adept Technical Solutions Limited | Construction | 2018 |
| Adicote Limited | Wholesale & retail | 2015 |
| Adkins Group Limited | Financial services | 2025 |
| Adkins Homes Lettings Limited | Real estate | 2019 |
| Adkins Property Group Ltd | Financial services | 2025 |
| Adrian LEE Consulting Limited | Professional & scientific | 2024 |
| Adus Healthcare UK Limited | Other services | 2013 |
| Advanced Battery Management Systems UK Limited | Professional & scientific | 2018 |
| Advanced Biointelligence Ltd | Professional & scientific | 2025 |
| Advanced Resuscitation Training Ltd | Education | 2024 |
| Advanced Structural Monitoring Limited | Manufacturing | 2007 |
| Advanta Limited | Professional & scientific | 2026 |
| Adventure Activity Associates Limited | Arts & recreation | 2006 |
| Adyar House (Freehold) Limited | Households | 2016 |
| AEB Investments Limited | Health & social care | 2014 |
| Aels 101 Limited | Real estate | 2004 |
| Aeris Transformation Partners Ltd | Information & communication | 2026 |
| Aesthetic Angels Ltd | Other services | 2017 |
| Aesthetic Practitioner Support Limited | Health & social care | 2023 |
| Aether Vehicle Technologies Ltd | Professional & scientific | 2023 |
| AFC Whyteleafe Limited | Arts & recreation | 2021 |
| Afdi Property Holdings Limited | Real estate | 2026 |
| Affect in Limited | Professional & scientific | 2015 |
| Affiliate Racing Ltd | Arts & recreation | 2023 |