| Assessus Limited | Health & social care | 2013 |
| Asset Intelligence Portfolio Management Ltd | Financial services | 2019 |
| Asset Intelligence Research Limited | Financial services | 2009 |
| Asset Plan Ltd | Information & communication | 2012 |
| Asset Protection Security Services Ltd | Administrative & support | 2017 |
| Asset Tree Ltd | Real estate | 2017 |
| Asset Wise Advisory Ltd | Real estate | 2025 |
| Assets Produce Wealth Ltd | Real estate | 2022 |
| Assistance Consultancy Limited | Professional & scientific | 2014 |
| Assisted Sale Property UK Ltd | Real estate | 2021 |
| Assisted System Solution Limited | Administrative & support | 2019 |
| Associate Events Limited | Arts & recreation | 2010 |
| Associated Stairlifts Limited | Other services | 1998 |
| Association for Learning Environments Limited | Education | 2011 |
| Association for Womens Trade and Commerce UK CIC | Administrative & support | 2024 |
| Association of Afghan United in Britain | Education | 2010 |
| Association of Business Accountants | Professional & scientific | 2006 |
| Association of Taxation Practitioners | Other services | 2016 |
| Assure Residential Care Ltd | Health & social care | 2020 |
| Assured Communications (Leicester) Ltd | Information & communication | 2011 |
| Assured Design Ltd | Information & communication | 2020 |
| Assured Mortgage Services Ltd | Financial services | 2019 |
| Assured Perfusion and Medical Services Limited | Health & social care | 2015 |
| Assured Risk Consulting Limited | Professional & scientific | 2019 |
| Assured Transport and Logistics Limited | Transport & logistics | 2025 |
| Assyst Company Limited | Information & communication | 2015 |
| AST Lets Ltd | Real estate | 2025 |
| Astanamdes Ltd | Public administration | 2021 |
| Astar Clubs Ltd | Hospitality | 2017 |
| Asterina Auto Limited | Wholesale & retail | 2025 |
| Asteroo Ltd | Wholesale & retail | 2025 |
| Asthee Snayu Vikiran Chikitshak Ltd | Health & social care | 2024 |
| Astill Lodge Food Hub Ltd | Hospitality | 2025 |
| Astill Lodge Pharmacy Limited | Wholesale & retail | 2002 |
| Astill Planning Consultants Limited | Professional & scientific | 2012 |
| Astley Advisory Group Limited | Professional & scientific | 2024 |
| Astley Construction Limited | Construction | 2022 |
| Astley FAB Limited | Manufacturing | 2000 |
| Astley Fencing Limited | Wholesale & retail | 2000 |
| Astley Fencing SAW Mill Limited | Manufacturing | 2000 |
| Astley Marketing Limited | Professional & scientific | 2009 |
| Astley Nails Ltd | Other services | 2023 |
| Astley Properties Ltd | Real estate | 2020 |
| Asto Ltd | Professional & scientific | 2012 |
| Aston & Co Maintenance Limited | Administrative & support | 2023 |
| Aston Event Solutions Limited | Other services | 2024 |
| Aston Foxhill Solutions Limited | Administrative & support | 2023 |
| Aston Levene & Britton Ltd | Financial services | 2021 |
| Aston Window Systems Leicester Ltd | Manufacturing | 2019 |
| Astoncruz Sports Ltd | Other services | 2016 |
| Astonishing Dreams Ltd | Real estate | 2023 |
| Astoria Scalford Hall Ltd | Other services | 2026 |
| ASTRAL9 Ltd | Wholesale & retail | 2025 |
| Astralis Collective Limited | Real estate | 2025 |
| Astronomical Ltd | Professional & scientific | 2023 |
| Astropartpicker Ltd | Wholesale & retail | 2023 |
| Astute Protection Limited | Financial services | 2026 |
| Astute Traders Limited | Wholesale & retail | 2019 |
| Astwick Ltd | Real estate | 2025 |
| Astwold Limited | Professional & scientific | 2016 |
| Astynmarr Motors Ltd | Wholesale & retail | 2020 |
| Asure Consulting Group Ltd | Education | 2026 |
| Asus Leicester Ltd | Hospitality | 2026 |
| ASV (UK) Ltd | Administrative & support | 2007 |
| ASV Investments Limited | Real estate | 2006 |
| Aswad Media Limited | Professional & scientific | 2024 |
| Aswarby Key Ltd | Construction | 2016 |
| Aswat Packaging Limited | Wholesale & retail | 2007 |
| Asya Catering Ltd | Wholesale & retail | 2023 |
| Asya Ltd | Hospitality | 2025 |
| Asymic Limited | Wholesale & retail | 2025 |
| Asyncro Limited | Professional & scientific | 2020 |
| Asyym Technology Ltd | Information & communication | 2025 |
| ASZ Food Ltd | Manufacturing | 2023 |
| AT Care Home Ltd | Health & social care | 2025 |
| AT Couriers Ltd | Transport & logistics | 2017 |
| AT Empire Ltd | Households | 2025 |
| AT Foods Limited | Hospitality | 2024 |
| AT Hampson Services Ltd | Manufacturing | 2024 |
| AT Home Help Limited | Households | 2019 |
| AT Management Limited | Information & communication | 2007 |
| AT Properties (Leic) Assets Ltd | Real estate | 2017 |
| AT Tech Global Limited | Information & communication | 2026 |
| AT the Door Limited | Real estate | 2023 |
| At-Pas*Bs Limited | Professional & scientific | 2016 |
| AT7 Ltd | Other services | 2025 |
| Atajere Ltd | Wholesale & retail | 2024 |
| Atalights Limited | Administrative & support | 2022 |
| Atba Ltd | Health & social care | 2020 |
| Atec Design Ltd | Professional & scientific | 2021 |
| Ateeg Investments | Financial services | 2025 |
| Atelier Food Limited | Hospitality | 2026 |
| Atelier Luxe Interiors Ltd | Professional & scientific | 2026 |
| Atelier MA Limited | Construction | 2019 |
| Atelier VOX Marketing Limited | Professional & scientific | 2025 |
| Atex-Supplies Ltd | Wholesale & retail | 2023 |
| Ateyant Haulage Ltd | Transport & logistics | 2011 |
| Ateyant Transport Ltd | Transport & logistics | 2019 |
| Atfire Ltd | Construction | 2020 |
| ATG Business Ltd | Wholesale & retail | 2025 |