| A R Pearson Limited | Health & social care | 2010 |
| A S Metal Recycling Limited | Extraterritorial | 2023 |
| A S Propetiz Limited | Real estate | 2021 |
| A&A Chauffeur Limited | Transport & logistics | 2025 |
| A&G Cousins Construction Ltd | Construction | 2025 |
| A&I Premium Trading Ltd | Wholesale & retail | 2014 |
| A&M Advisory Ltd | Information & communication | 2025 |
| A&M Dinev Ltd | Agriculture & fishing | 2024 |
| A&S Wholesale Ltd | Wholesale & retail | 2022 |
| A.A.A Financial Ltd | Financial services | 2025 |
| A.Cain(Funeral Services)Limited | Other services | 1963 |
| A.F.D. Catering Limited | Hospitality | 2005 |
| A.M. Transformers Limited | Manufacturing | 1998 |
| A.R.C.(Western)Limited | Professional & scientific | 1967 |
| A1 Services (Manchester) Limited | Water & waste | 2003 |
| A2O Consultants Limited | Professional & scientific | 2010 |
| A2Z Carz Limited | Wholesale & retail | 2024 |
| A2Z Commercial Services Ltd | Professional & scientific | 2017 |
| A2Z Mindset Press Ltd | Information & communication | 2024 |
| A2Z Poster Campaigns Ltd | Professional & scientific | 2025 |
| A2Z UK Traders Ltd | Wholesale & retail | 2020 |
| A4 Builders Limited | Construction | 2020 |
| A4 Electrical Services Ltd | Construction | 2003 |
| A4 Interiors Ltd | Manufacturing | 2023 |
| A4 Local Ltd | Wholesale & retail | 2024 |
| A4 Transport Ltd | Transport & logistics | 2019 |
| A41 Estates Limited | Construction | 2025 |
| AA & BI Ltd | Real estate | 2024 |
| AA NAT GAS Ltd | Energy | 2023 |
| AA SPV Ltd | Real estate | 2020 |
| AA1 Global Solutions Ltd | Education | 2026 |
| AAA Vision Bookkeeping & Consulting Ltd | Professional & scientific | 2024 |
| AAC Systems Ltd | Information & communication | 2005 |
| Aadict Consultancy Ltd | Information & communication | 2024 |
| Aairah Services Limited | Professional & scientific | 2016 |
| Aajm Special Pro Body Work Ltd Ltd | Wholesale & retail | 2026 |
| Aamro Global Private Ltd | Transport & logistics | 2020 |
| Aapa Roti Ltd | Hospitality | 2025 |
| AAR Consulting Limited | Professional & scientific | 2022 |
| Aariz Investment Ltd | Real estate | 2020 |
| Aarz Limited | Information & communication | 2018 |
| Aasj Plumbing and Heating Services Ltd | Construction | 2025 |
| AB & Co Ventures Ltd | Hospitality | 2025 |
| AB Agro Ltd | Agriculture & fishing | 2025 |
| AB Refurb Ltd | Construction | 2024 |
| Abbeville Marketing Consultancy Limited | Professional & scientific | 2015 |
| Abbey Solutions Limited | Professional & scientific | 2019 |
| Abbott (UK) Finance Limited | Financial services | 2000 |
| Abbott (UK) Holdings Limited | Financial services | 1999 |
| Abbott Asia Holdings Limited | Financial services | 2001 |
| Abbott Asia Investments Limited | Financial services | 2005 |
| Abbott Australasia Holdings Limited | Financial services | 2012 |
| Abbott Capital India Limited | Financial services | 2001 |
| Abbott Equity Holdings Unlimited | Financial services | 2001 |
| Abbott Healthcare Products Ltd | Wholesale & retail | 1969 |
| Abbott Laboratories Limited | Wholesale & retail | 1937 |
| Abbott Laboratories Trustee Company Limited | Financial services | 1952 |
| Abbott Rapid Diagnostics Limited | Manufacturing | 1983 |
| Abbott UK Investments Limited | Professional & scientific | 2019 |
| Abbott UK Subsidiary Limited | Financial services | 2021 |
| Abbott Vascular Devices (2) Limited | Manufacturing | 2001 |
| Abbott Vascular Devices Limited | Financial services | 1984 |
| Abbvie Australasia Holdings Limited | Manufacturing | 2001 |
| Abbvie Ltd | Wholesale & retail | 2012 |
| Abbvie Trustee Company Limited | Extraterritorial | 2012 |
| Abbvie UK Holdco Limited | Financial services | 2012 |
| ABD International Ltd | Information & communication | 2019 |
| Aberlour Trading Ltd | Manufacturing | 2022 |
| ABG Pharma Consultancy Ltd | Administrative & support | 2015 |
| Abico Executive Travel Ltd | Transport & logistics | 2026 |
| Able 2 Plumbing Limited | Extraterritorial | 2011 |
| Able and Baker Ltd | Professional & scientific | 2020 |
| Abner Advisory Limited | Professional & scientific | 2021 |
| Abrahamsen Limited | Administrative & support | 2017 |
| Abraxys Limited | Administrative & support | 2004 |
| Abrugo Estates Limited | Real estate | 2022 |
| Absolute Mortgage Advice Ltd | Financial services | 2013 |
| Absolute Optics Ltd | Health & social care | 2018 |
| Absolute Surveying LDK Limited | Professional & scientific | 2021 |
| Absolutely Leisure | Arts & recreation | 2009 |
| Absolutely Together | Arts & recreation | 2013 |
| Absolutely Together Trading Ltd | Arts & recreation | 2010 |
| Abstract Concept Limited | Professional & scientific | 2005 |
| Abtech Services Ltd | Information & communication | 2016 |
| Abundance Living Limited | Other services | 2023 |
| AC Commercial Estates Ltd | Real estate | 2025 |
| AC Group of Companies Ltd | Financial services | 2024 |
| AC Motor Car Company Limited | Wholesale & retail | 2016 |
| AC Motor Group Limited | Manufacturing | 2017 |
| AC Spires Engineering Limited | Construction | 2022 |
| Academic, Professional Training and Publishing Limited | Professional & scientific | 1998 |
| Accelerated Professional Learning Limited | Education | 2021 |
| Access Law Online Ltd | Education | 2018 |
| Access Office E-Sales Limited | Wholesale & retail | 2016 |
| Access Office Furniture Solutions Limited | Wholesale & retail | 2015 |
| Accokg PLC | Mining & quarrying | 2024 |
| Accolade Glass Box Limited | Construction | 2024 |
| Accolade Holdings Ltd | Administrative & support | 2018 |
| Accountancy Assist (UK) Limited | Professional & scientific | 2013 |
| Accountancy Guru for YOU Ltd | Professional & scientific | 2022 |