| Albator Ltd | Real estate | 2021 |
| Albermarle Pianos Limited | Manufacturing | 2003 |
| Albert Spedition Ltd | Other services | 2019 |
| Albion Business Consultancy Limited | Information & communication | 2024 |
| Albion House (Dunston Riverside) Management NO 1 Limited | Households | 2003 |
| Albion House (Dunston Riverside) Management NO 2 Limited | Households | 2003 |
| Albion Retreat Ltd | Hospitality | 2020 |
| Albright Cleaning & Maintenance Services Limited | Construction | 2012 |
| Albro Services Limited | Other services | 2020 |
| Alcester Park (Maisonettes) Management Company Limited | Households | 2021 |
| Alchemy (Myrtle Street) Management Company Limited | Households | 2005 |
| Alcom Environmental Limited | Construction | 2024 |
| Alcrismar Ltd | Administrative & support | 2021 |
| Alderson Building Company Limited | Construction | 2007 |
| Alecra Limited | Construction | 1984 |
| Alekttd Limited | Administrative & support | 2018 |
| Alemis Board Solutions Limited | Professional & scientific | 2024 |
| Alenco (Holdings) Limited | Professional & scientific | 1950 |
| Aleph Zain Limited | Real estate | 2009 |
| Alex Formwork Ltd | Construction | 2019 |
| Alexander & Moise Group Ltd | Construction | 2017 |
| Alexander Grant Associates Ltd | Professional & scientific | 2012 |
| Alexander Park (Aldershot) Residents Management Company Limited | Households | 2026 |
| Alexander Wood Flooring Ltd | Construction | 2022 |
| Alexanderparekh Ltd | Wholesale & retail | 2026 |
| Alexanderplumb Properties Limited | Real estate | 2021 |
| Alexandra Road Congregational Church | Other services | 2025 |
| Alexandrucleaning Ltd | Transport & logistics | 2016 |
| ALF Civil Ltd | Construction | 2025 |
| Alfa Online Trading Ltd | Wholesale & retail | 2020 |
| Alfa Projects Ltd | Administrative & support | 2011 |
| Alfred Ayres Limited | Construction | 2022 |
| Alfred Dunn Accountancy Ltd | Professional & scientific | 2014 |
| Algorithmia Ltd | Information & communication | 2022 |
| ALH Recruitment Limited | Administrative & support | 2014 |
| Align Projects Limited | Professional & scientific | 2025 |
| Alignment Matters Limited | Professional & scientific | 2025 |
| Alignment Solutions Limited | Health & social care | 2025 |
| Alin G Gheorghe Ltd | Transport & logistics | 2023 |
| Alison Court Management Company Limited | Households | 1991 |
| Alitwell LLP | | 2015 |
| Aljenna Ltd | Professional & scientific | 2023 |
| Alkerden Heights (Parcel 5A) Management Company Limited | Real estate | 2023 |
| ALL Aboard Horsebox Hire Ltd | Administrative & support | 2021 |
| ALL Aspect Fitout Ltd | Construction | 2018 |
| ALL Aspects Building Ltd | Construction | 2015 |
| ALL Backs Physio Hemel Ltd | Health & social care | 2021 |
| ALL Direction Trans Ltd | Transport & logistics | 2021 |
| ALL From Zero Construct Limited | Construction | 2024 |
| ALL Gardens Limited | Administrative & support | 2003 |
| ALL N ALL Household Limited | Wholesale & retail | 2016 |
| ALL Seasons Equipment Ltd | Manufacturing | 2017 |
| ALL Stage Carpentry Ltd | Construction | 2025 |
| ALL the JS Investments Limited | Real estate | 2022 |
| Allchemy Productions Limited | Arts & recreation | 2024 |
| Allegro Holdings Limited | Real estate | 2021 |
| Allenwaste Management and Cable Contractors Ltd | Construction | 2024 |
| Aller Brook Ltd | Professional & scientific | 2010 |
| Allied Water Ltd | Administrative & support | 2020 |
| Alloy Stars Ltd | Wholesale & retail | 2015 |
| Alluria Limited | Health & social care | 2006 |
| Alluria Property Group Ltd | Real estate | 2016 |
| Almaris Property Investments Ltd | Real estate | 2026 |
| Almaya (U.K.) Limited | Wholesale & retail | 1981 |
| Almaya International Limited | Wholesale & retail | 1990 |
| Alopa Limited | Wholesale & retail | 2017 |
| ALP Pizza Ltd | Hospitality | 2025 |
| Alpha 24/24 Ltd | Transport & logistics | 2024 |
| Alpha and JAM UK Limited | Manufacturing | 2025 |
| Alpha Brothers Ltd | Construction | 2017 |
| Alpha Clinical Limited | Professional & scientific | 2015 |
| Alpha One 3D Ltd | Manufacturing | 2026 |
| Alphabet Social Work Ltd | Health & social care | 2015 |
| Alphain Ltd | Real estate | 2022 |
| Alphareigns Limited | Wholesale & retail | 2024 |
| Alpine Coaching Limited | Arts & recreation | 2011 |
| Alpinefox Recruitment Ltd | Administrative & support | 2023 |
| Alsys Ltd | Information & communication | 2016 |
| Altair (UK) Ltd | Manufacturing | 2013 |
| Altera (PVT) Limited | Construction | 2025 |
| Alterior Limited | Construction | 2003 |
| Alternative Plumbing and Heating Ltd | Construction | 2019 |
| Alternative Strategies Limited | Financial services | 2018 |
| Alternatives Trading Limited | Wholesale & retail | 2013 |
| Alternatives Watford | Health & social care | 2002 |
| Altior Digital Ltd | Information & communication | 2026 |
| Altitude 8611 Dining Ltd | Hospitality | 2026 |
| ALV Contractors Ltd | Construction | 2026 |
| Alvalan Ltd | Professional & scientific | 2025 |
| AM Advisory Services LLP | | 2020 |
| AMA Haulage Ltd | Transport & logistics | 2023 |
| Ama&M Construction Ltd | Construction | 2014 |
| Amago Holidays Ltd | Administrative & support | 2017 |
| Amalia Property Ltd | Real estate | 2016 |
| Amara 25 Ltd | Hospitality | 2025 |
| Amazing Again Ltd | Administrative & support | 2017 |
| Amazon Property Solutions Ltd | Construction | 2025 |
| Ambassador Apartments (Salford) Limited | Households | 2004 |
| Amber (Cherry Trees) Management Company Limited | Households | 2005 |
| Amberside Accounting Ltd | Professional & scientific | 2013 |