| A.T. Care Limited | Administrative & support | 2025 |
| A.T. Finn Consulting Ltd | Extraterritorial | 2014 |
| A.To.Zii Ltd | Construction | 2022 |
| A.V.R. Group Limited | Information & communication | 1976 |
| A.Vlies Northwich Metals Limited | Water & waste | 2000 |
| A.Y.O Accounting Solutions Limited | Professional & scientific | 2025 |
| A1 Computer Repairs Ltd | Other services | 2000 |
| A1 Roof Repairs Ltd | Construction | 2024 |
| A103 One Park West Ltd | Real estate | 2026 |
| A1TANG Limited | Professional & scientific | 2018 |
| A2 Talent Limited | Administrative & support | 2024 |
| A4 Lite Ltd | Health & social care | 2023 |
| A4 Studios C.I.C. | Arts & recreation | 2016 |
| A4SUPPLIER Ltd | Administrative & support | 2015 |
| AA Dentistry Ltd | Health & social care | 2022 |
| AAA Property Services Ltd | Real estate | 2022 |
| Aaaahhhh-Eek! Limited | Information & communication | 2018 |
| Aadit Ltd | Health & social care | 2025 |
| Aaditri IT Solutions Ltd | Information & communication | 2022 |
| Aaharush Technologies Limited | Information & communication | 2022 |
| AAI Risk Consultancy Limited | Administrative & support | 2022 |
| Aairaz Limited | Real estate | 2026 |
| AAJ Construction Limited | Administrative & support | 2007 |
| AAJ Khan Investment Property Ltd | Real estate | 2024 |
| AAJ Property Investments Ltd | Real estate | 2020 |
| AAJ Supply Tool Hire Ltd | Administrative & support | 2025 |
| AAL Development & Consultancy Ltd | Education | 2014 |
| AAN Fusion Ltd | Transport & logistics | 2024 |
| Aaqg Tech Limited | Wholesale & retail | 2025 |
| Aardvark Properties Limited | Real estate | 1998 |
| Aargon Enterprises Ltd | Households | 2013 |
| Aaron and Alitza Properties Ltd | Real estate | 2019 |
| Aarv Homes Investment Ltd | Real estate | 2023 |
| Aaryo Ltd | Real estate | 2022 |
| Aashriproperties Ltd | Real estate | 2024 |
| Aayush Homes Limited | Real estate | 2022 |
| Aayush Solutions Limited | Information & communication | 2018 |
| AAZ Estates Commercial Limited | Real estate | 2025 |
| AB Tree Care Limited | Administrative & support | 2021 |
| Abbacus Limited | Administrative & support | 2005 |
| Abberley Hall Management Company Limited | Households | 2000 |
| Abbey Real Estate (Manchester) Limited | Real estate | 2023 |
| Abbeyvale (Willow Court) Management Limited | Households | 1990 |
| Abbott Vision North Ltd | Arts & recreation | 2019 |
| Abbotts Estate Agents Ltd | Professional & scientific | 1991 |
| ABC Construction Manchester Ltd | Construction | 2019 |
| ABC Music Publishing Limited | Information & communication | 1996 |
| ABC Property Investments Northwest Limited | Real estate | 2024 |
| ABC Sports Learning Ltd | Education | 2020 |
| ABC Trailer Solutions Limited | Wholesale & retail | 2020 |
| Abdullah (NW) Limited | Health & social care | 2016 |
| Abeer Shehadeh Care Limited | Health & social care | 2023 |
| Abelian Computing Limited | Administrative & support | 2024 |
| Abersoch LLP | | 2006 |
| Abersoch Quality Homes Limited | Real estate | 2018 |
| ABG Europe (UK) Limited | Administrative & support | 2021 |
| Abg-Dockers Limited | Financial services | 2025 |
| Abg-Glow UK Limited | Financial services | 2025 |
| Abg-Tb Bidco (UK) Limited | Financial services | 2022 |
| Abg-Tb Holdco (UK) Limited | Financial services | 2022 |
| Abg-Tb Ipco (UK) Limited | Administrative & support | 2021 |
| Abg-Tb Topco (UK) Limited | Financial services | 2022 |
| Abgene Limited | Manufacturing | 2005 |
| Abhidiya Investments Ltd | Financial services | 2026 |
| Abianne Ltd | Professional & scientific | 2016 |
| Abii 2 Limited | Extraterritorial | 2019 |
| Abinwal Limited | Information & communication | 2021 |
| ABK Corporation Limited | Wholesale & retail | 2018 |
| ABK Process Limited | Professional & scientific | 2022 |
| ABL IT Limited | Information & communication | 2022 |
| Able Fencing Ltd | Construction | 2016 |
| Able Joinery Ltd | Construction | 2002 |
| Able Marquees Limited | Construction | 2014 |
| Abney Place (Cheadle) Management Company Limited | Households | 2007 |
| About Change Communications Limited | Administrative & support | 2005 |
| ABP Consulting Limited | Administrative & support | 2016 |
| Abra Group Limited | Financial services | 2022 |
| Absolute Care at Home Ltd | Other services | 2005 |
| Absolute Clean at Home Ltd | Administrative & support | 2018 |
| Absolute Dental Limited | Health & social care | 2018 |
| Absolute Packaging Limited | Manufacturing | 2011 |
| Absolute Spill KIT Solution Limited | Wholesale & retail | 2017 |
| Absolute Testing Services Ltd | Information & communication | 2018 |
| Absolutely Red Limited | Professional & scientific | 2023 |
| Abstract Incentives Limited | Administrative & support | 2008 |
| Abstracts by Design Ltd | Arts & recreation | 2022 |
| Absurd Ventures in Games (UK) Ltd | Information & communication | 2021 |
| Absynth Solutions Limited | Administrative & support | 2013 |
| AC Creative Communications Limited | Professional & scientific | 2025 |
| AC Erlam Ltd | Construction | 2019 |
| AC IT Management Limited | Professional & scientific | 2022 |
| AC Safety Consulting Limited | Administrative & support | 2025 |
| Acacia Learning Limited | Education | 2007 |
| Acacia Pharma Group Limited | Professional & scientific | 2015 |
| Acacia Pharma Limited | Professional & scientific | 2006 |
| Acacia Property Group Limited | Real estate | 2021 |
| Acadia Pharma Limited | Health & social care | 2015 |
| Acbjk Ltd | Wholesale & retail | 2019 |
| Access First LEI Limited | Financial services | 2012 |
| Access Holdings Management Company Limited | Professional & scientific | 2025 |