| AKL Trade Enterprise Limited | Wholesale & retail | 2019 |
| Alakh Ltd | Real estate | 2011 |
| Albion Pressings Ltd | Manufacturing | 2023 |
| Albrighton Anglers Limited | Agriculture & fishing | 2006 |
| Alexandru Bratu Limited | Transport & logistics | 2024 |
| ALF Homes Ltd | Real estate | 2018 |
| Alignment Scaffolding Solutions Ltd | Construction | 2014 |
| ALL Heating Services Limited | Manufacturing | 2006 |
| ALL Round Plumbing & Heating Ltd | Construction | 2023 |
| ALL Traffic Holdings Ltd | Financial services | 2023 |
| ALL Traffic Products Ltd | Manufacturing | 2020 |
| ALL Weather Driveways & Landscapes Ltd | Administrative & support | 2026 |
| Allen DEW International Limited | Information & communication | 2020 |
| Alma Lodge Limited | Real estate | 2022 |
| ALO Serv Ltd | Wholesale & retail | 2023 |
| Alpha College Online Limited | Education | 2020 |
| Alpha Kroon Consortium Limited | Administrative & support | 2019 |
| Alphagardenservices Ltd | Arts & recreation | 2025 |
| Alphexglobal Ltd | Transport & logistics | 2024 |
| Altira Limited | Professional & scientific | 2024 |
| Alvary Group Ltd | Administrative & support | 2025 |
| AM DU Services Ltd | Real estate | 2025 |
| Aman Freight Ltd | Transport & logistics | 2021 |
| Amar Carriers Limited | Transport & logistics | 2024 |
| Ama’S Global Market Ltd | Wholesale & retail | 2022 |
| Ambar Foods Ltd | Wholesale & retail | 2025 |
| AMC Transport (UK) Limited | Transport & logistics | 2015 |
| AMG Music Limited | Information & communication | 2021 |
| AN Financial Ltd | Real estate | 2019 |
| Anami Construction Ltd | Construction | 2019 |
| Anami Estates Ltd | Real estate | 2024 |
| Anami Highways Ltd | Construction | 2022 |
| Anant Transport Limited | Transport & logistics | 2026 |
| Andersons Beds Limited | Manufacturing | 2017 |
| Angadbahri Limited | Wholesale & retail | 2025 |
| Angolo Fresco Limited | Wholesale & retail | 2026 |
| Ann's Food Services Limited | Hospitality | 2022 |
| Anoop Transport Ltd | Transport & logistics | 2020 |
| Antalya Turkish Ltd | Hospitality | 2026 |
| Antjohnson Cleaning Services Ltd | Administrative & support | 2024 |
| ANU Hair & Beauty Ltd | Other services | 2024 |
| AP Holdings Group Limited | Financial services | 2023 |
| AP Housing & Properties Ltd | Real estate | 2025 |
| AP Plumbing and GAS Limited | Construction | 2018 |
| AP Virk Group Ltd | Real estate | 2026 |
| Apex Scientific Ltd | Professional & scientific | 2023 |
| Apni Property Limited | Real estate | 2024 |
| App Universe Ltd | Information & communication | 2025 |
| APV House Limited | Real estate | 2022 |
| Aqua Bath Ltd | Construction | 2022 |
| Aqua Bathrooms (WM) Limited | Wholesale & retail | 2014 |
| Aqua Bathrooms Insulation Limited | Construction | 2020 |
| Aqua Properties WM Ltd | Real estate | 2021 |
| ARC Guard Ltd | Professional & scientific | 2024 |
| ARC Guardian Ltd | Manufacturing | 2025 |
| Arcelor SSC UK Barking Limited | Manufacturing | 1990 |
| Arcelormittal Distribution Solutions UK Limited | Manufacturing | 1982 |
| Arco Services Limited | Energy | 1998 |
| Aria Galaxy Ltd | Wholesale & retail | 2025 |
| Arigatoshopper Ltd | Wholesale & retail | 2021 |
| Arise Therapies International CIC | Health & social care | 2025 |
| Arjancargo Ltd | Transport & logistics | 2025 |
| ARK Racing Limited | Manufacturing | 2003 |
| Arly Group Ltd | Real estate | 2024 |
| Armaan Media Ltd | Other services | 2018 |
| Armaan Services Ltd | Construction | 2024 |
| Armaan World Records Ltd | Arts & recreation | 2025 |
| Arnie & Toad Ltd | Real estate | 2024 |
| Arran Isle Holdings Limited | Professional & scientific | 1910 |
| Arran Isle Limited | Professional & scientific | 2009 |
| Arrowcraft Composite Engineering Limited | Manufacturing | 2006 |
| Artem Anima Ltd | Wholesale & retail | 2024 |
| Artist Valley Tyres Limited | Wholesale & retail | 2018 |
| ARX Apparel and PPE Limited | Wholesale & retail | 2024 |
| AS Acconsult Limited | Professional & scientific | 2026 |
| Asafo Wholesale Market Ltd | Wholesale & retail | 2026 |
| Ascend BIM Ltd | Professional & scientific | 2025 |
| Asees Ltd | Transport & logistics | 2024 |
| ASG Industries Limited | Transport & logistics | 2012 |
| Ashleon Limited | Transport & logistics | 2014 |
| Ashley Homes Midland Limited | Real estate | 2024 |
| Ashwina Superstores Limited | Wholesale & retail | 2018 |
| ASK Immigration Lawyers Ltd | Administrative & support | 2019 |
| ASK4PROPERTIES Ltd | Real estate | 2025 |
| Asng Ltd | Wholesale & retail | 2026 |
| Aspire Mentoring Services Ltd | Administrative & support | 2017 |
| Aspray International Limited | Transport & logistics | 1999 |
| Assetize Limited | Real estate | 2022 |
| Astrix Interiors Limited | Construction | 2013 |
| Atam-Noor Trading Limited | Wholesale & retail | 2026 |
| Aura and Essence Lounge Ltd | Other services | 2025 |
| Aura RB Cleaning Ltd | Administrative & support | 2020 |
| Autism and ME World Community Interest Company | Professional & scientific | 2024 |
| Auto Bits Online Limited | Wholesale & retail | 2014 |
| Auto Bits Scrap Metal Limited | Water & waste | 2008 |
| Auto Keys Direct Ltd | Financial services | 2022 |
| Autoexpertz Limited | Wholesale & retail | 2021 |
| Autorite Industries Willenhall Limited | Wholesale & retail | 2010 |
| Avasar Recruitment Ltd | Administrative & support | 2023 |
| Avee Transport Limited | Transport & logistics | 2020 |