| Alexander Consultancy Limited | Professional & scientific | 2015 |
| Alexander James Developments Limited | Construction | 2024 |
| Alexander Knight Business Solutions Ltd | Professional & scientific | 2010 |
| Alexander Knight Properties Ltd | Real estate | 2017 |
| Alexander Maxime Limited | Information & communication | 2024 |
| Alexander Tree Services Limited | Agriculture & fishing | 2012 |
| Alexis General Construction Ltd | Construction | 2021 |
| Alexony Limited | Information & communication | 2008 |
| Alexpro Cleaning Services Ltd | Administrative & support | 2025 |
| Alfa Powder Coating Limited | Manufacturing | 2015 |
| Alfhaily Limited | Health & social care | 2014 |
| Alfie Allen Limited | Other services | 2014 |
| Alfie James Productions Limited | Arts & recreation | 2020 |
| Alflips Ltd | Wholesale & retail | 2024 |
| Alford Assets Limited | Hospitality | 2022 |
| Alfresco Lighting Designs Limited | Professional & scientific | 2023 |
| Alfresco Systems (UK) Ltd | Manufacturing | 2025 |
| Algas Services Ltd | Construction | 2020 |
| Algo Technology Limited | Administrative & support | 2011 |
| ALI 24/7 Ltd | Transport & logistics | 2017 |
| ALI Estates Management Limited | Real estate | 2020 |
| ALI Healthcare Limited | Health & social care | 2012 |
| ALI Mashadi Limited | Financial services | 2020 |
| ALI Mashadi Properties Limited | Real estate | 2025 |
| ALI Taxi Services Limited | Transport & logistics | 2024 |
| Aliaj Ltd | Wholesale & retail | 2017 |
| Alice Andrews Studio Ltd | Professional & scientific | 2022 |
| Alices Boutique Limited | Manufacturing | 2014 |
| Aligator Systems (UK) Limited | Wholesale & retail | 2003 |
| Alignity Hub Ltd | Information & communication | 2026 |
| Alis Global Holdings Ltd | Financial services | 2023 |
| Alis Property Investments Ltd | Real estate | 2026 |
| ALK Groundworks Ltd | Construction | 2014 |
| Alkag Ltd | Construction | 2018 |
| ALL 4 Mechanical Limited | Construction | 2024 |
| ALL 4 U Contract Services Ltd | Administrative & support | 2025 |
| ALL About Christmas Limited | Wholesale & retail | 2014 |
| ALL Ages UK Ltd | Administrative & support | 2016 |
| ALL Bikes Motorcycle Training Ltd | Education | 2013 |
| ALL Care Plus Limited | Administrative & support | 2007 |
| ALL Cleared Essex Skip Hire Ltd | Water & waste | 2022 |
| ALL Elements Building Company Ltd | Construction | 2025 |
| ALL Football Shirts Ltd | Wholesale & retail | 2022 |
| ALL Health Solution Ltd | Health & social care | 2018 |
| ALL in Resources Limited | Construction | 2021 |
| ALL Industry Professionals Ltd | Information & communication | 2026 |
| ALL Plastering Solutions Limited | Construction | 2021 |
| ALL Property Care & Managment Ltd | Hospitality | 2026 |
| ALL Saints Close (Little Melton) Management Company Limited | Real estate | 2019 |
| ALL the Aces Limited | Real estate | 2020 |
| ALL Things Horses Ltd | Wholesale & retail | 2023 |
| ALL Things Print (UK) Ltd | Manufacturing | 2009 |
| ALL Trans Autos Ltd | Wholesale & retail | 2013 |
| ALL Ways Wired Ltd | Construction | 2002 |
| ALL Year Maintenance Ltd | Administrative & support | 2018 |
| Allard Office Furniture Limited | Wholesale & retail | 2002 |
| Allcrates Limited | Transport & logistics | 2005 |
| Allegiance FM Ltd | Construction | 2020 |
| Allegiance Group Ltd | Administrative & support | 2021 |
| Allegiance Haulage and Transport Ltd | Transport & logistics | 2022 |
| Allehart Ltd | Professional & scientific | 2015 |
| Allehart Promotions LLP | | 2011 |
| Allen Leslie Associates Limited | Professional & scientific | 2005 |
| Allen Lettings Ltd | Real estate | 2021 |
| Allen Newport Limited | Mining & quarrying | 1934 |
| Allen's Plumbing & Heating Services Limited | Construction | 2019 |
| Allens Farm Partners Ltd | Agriculture & fishing | 2025 |
| Allens Farm Properties Ltd | Real estate | 2010 |
| Allerdale Beverage Ltd | Hospitality | 2025 |
| Allerdale Food Ltd | Hospitality | 2025 |
| Allerdale Property Ltd | Real estate | 2025 |
| Allerdale Rooms Ltd | Real estate | 2025 |
| Alley Pond Close Management Company Limited | Professional & scientific | 2016 |
| Allied Health Support Limited | Health & social care | 2018 |
| Allied Trading Limited | Wholesale & retail | 2014 |
| Allied Universal Limited | Financial services | 1996 |
| Allkem Logistics Ltd | Transport & logistics | 2025 |
| Allneedsnationwide Limited | Manufacturing | 2016 |
| Allpress Plumbing & Heating Ltd | Manufacturing | 2012 |
| Allsmartcars Ltd | Wholesale & retail | 2023 |
| Allston and Jones Building Limited | Construction | 2022 |
| Allum Properties Limited | Real estate | 2025 |
| Almel Properties Ltd | Real estate | 2025 |
| Almgren Limited | Health & social care | 2017 |
| ALMIGHTY1 Publishing Ltd | Information & communication | 2025 |
| Almondit Ltd | Information & communication | 2026 |
| ALO Accounting Limited | Professional & scientific | 2021 |
| Aloft Audio Ltd | Information & communication | 2025 |
| ALP Building Services Ltd | Construction | 2024 |
| Alpaca Acres C.I.C. | Health & social care | 2023 |
| Alpha Complex Training Ltd | Education | 2021 |
| Alpha Dora Group Ltd | Financial services | 2021 |
| Alpha Dora Holdings Ltd | Real estate | 2021 |
| Alpha Dora Limited | Construction | 2024 |
| Alpha Dora Property Group Ltd | Real estate | 2019 |
| Alpha Leap Limited | Information & communication | 2009 |
| Alpha MOT Centre Limited | Wholesale & retail | 2024 |
| Alpha Trust | Education | 2011 |
| Alphagrp Limited | Other services | 2016 |
| Alpharium Ltd | Wholesale & retail | 2023 |