| AS West Consultancy Limited | Wholesale & retail | 2026 |
| ASA Mediguide Ltd | Real estate | 2023 |
| ASC Planning Consultants Limited | Professional & scientific | 2024 |
| Ascensus AI Ltd | Information & communication | 2023 |
| Ascot EOT Limited | Financial services | 2024 |
| Ascot Knight Estates Limited | Real estate | 2024 |
| Asdale Cars Limited | Transport & logistics | 2018 |
| Asdale Pizza House Ltd | Hospitality | 2023 |
| ASE Future Transport Ltd | Transport & logistics | 2025 |
| Asenbra Investment Limited | Real estate | 2022 |
| Asfp Limited | Construction | 2023 |
| ASH & ABI Investments Ltd | Real estate | 2023 |
| ASH Tree Letting Ltd | Real estate | 2024 |
| Ash's Snacks Ltd | Hospitality | 2025 |
| ASHA1LANCASTER Ltd | Hospitality | 2023 |
| Ashbrow Garage Limited | Wholesale & retail | 2005 |
| Ashfield a Limited | Manufacturing | 2026 |
| Ashfield Refurbishments Limited | Manufacturing | 2000 |
| Ashford Court (Penistone Road) Management Company Limited | Households | 2005 |
| Ashglass Limited | Construction | 2008 |
| Ashraf Suleman Ltd | Health & social care | 2010 |
| Ashtree Roofing Limited | Construction | 1988 |
| Ashwini Uvaraj Foods Ltd | Manufacturing | 2025 |
| Ashwood Grange (Wakefield) Limited | Administrative & support | 1998 |
| Asia Medical Limited | Health & social care | 2025 |
| Asia Pacific Travel Limited | Administrative & support | 2002 |
| Asim Core Limited | Wholesale & retail | 2025 |
| ASK Julie Limited | Administrative & support | 2012 |
| ASM Product Holdings Limited | Manufacturing | 2019 |
| Asog Ltd | Wholesale & retail | 2023 |
| Asons Store Limited | Wholesale & retail | 2024 |
| Asot Properties Limited | Real estate | 2025 |
| Asova Holding Ltd. | Professional & scientific | 2014 |
| Aspen Electrical Ltd | Construction | 2017 |
| Aspen Spring Limited | Professional & scientific | 2017 |
| Aspire Commercial Services Limited | Professional & scientific | 2026 |
| Aspire Design Studio Ltd | Professional & scientific | 2019 |
| Aspire Group Yorkshire Ltd | Manufacturing | 2020 |
| Aspire Pro Sports Ltd | Manufacturing | 2016 |
| Aspiring Minds Tuition Limited | Education | 2024 |
| Asquith Property Holdings Ltd | Real estate | 2019 |
| Assar Hotels Ltd | Hospitality | 2018 |
| Assembly Agency Limited | Education | 2026 |
| Assent Holdings Limited | Hospitality | 2015 |
| Assent Planning Consultancy Limited | Professional & scientific | 2011 |
| Assentlingerie Ltd | Wholesale & retail | 2025 |
| Asset Management & Recovery Limited | Professional & scientific | 2014 |
| Associated Group Limited | Professional & scientific | 2020 |
| Assured Construction Solutions Limited | Construction | 2013 |
| Assyst Bullmer Limited | Manufacturing | 1987 |
| Asta Innovation Limited | Information & communication | 2021 |
| Astrofox Limited | Real estate | 1982 |
| Astute Property Deals Ltd | Real estate | 2025 |
| AT Commercial Services Ltd | Wholesale & retail | 2024 |
| Atelier Noir Limited | Wholesale & retail | 2025 |
| Atik Tamworth Ltd | Hospitality | 2024 |
| Atik Wrexham Ltd | Hospitality | 2024 |
| Atkin Automation Limited | Extraterritorial | 2014 |
| Atkin BHP Limited | Extraterritorial | 2014 |
| Atkinson Maintenance Solutions Limited | Administrative & support | 2006 |
| Atkinson Property Developments Ltd | Administrative & support | 2025 |
| Atkinson Software Ltd | Information & communication | 2026 |
| Atlanta Crispy (Wakefield) Ltd | Hospitality | 2025 |
| Atlantic PPE & Workwear Solutions Ltd | Manufacturing | 2018 |
| Atlas AVI Ltd | Construction | 2025 |
| Atomic Production Music Ltd | Information & communication | 2020 |
| Atrad Limited | Wholesale & retail | 2012 |
| ATS Heavy Equipment Engineers Ltd | Manufacturing | 2024 |
| Attends Healthcare Finance Limited | Manufacturing | 2007 |
| Attends Healthcare Limited | Manufacturing | 2007 |
| Attends Limited | Wholesale & retail | 1999 |
| Attentive Distribution Ltd | Transport & logistics | 2025 |
| ATZ Global Logistics Ltd | Transport & logistics | 2025 |
| Auburnx Properties Limited | Real estate | 2023 |
| Auckland (Opticians) Limited | Health & social care | 1971 |
| Audiovision Pros Ltd | Information & communication | 2025 |
| Audiozone WF1 Arts and Media Ltd | Arts & recreation | 2021 |
| Audit-Pro Ltd | Information & communication | 2025 |
| Auditsmart Limited | Professional & scientific | 2018 |
| Augmentory Group Limited | Financial services | 2015 |
| Augmentory.Com Limited | Manufacturing | 2015 |
| Aura Logistics Ltd | Transport & logistics | 2022 |
| Aurora Project Management Limited | Construction | 2026 |
| Aurum Entertainment Group Limited | Professional & scientific | 2026 |
| Aurus Limited | Construction | 2022 |
| AUS Trustees Limited | Administrative & support | 2021 |
| Austin Byrne Properties Limited | Real estate | 2006 |
| Austin Othniel Consulting Ltd | Information & communication | 2016 |
| Authentic Transformation CIC | Education | 2026 |
| Authentitec Limited | Administrative & support | 2005 |
| Auto Aroma Limited | Wholesale & retail | 2018 |
| Auto Electrical Supplies (Export) Limited | Wholesale & retail | 2014 |
| Auto Electrical Supplies Limited | Administrative & support | 1996 |
| Auto Kraft House Ltd | Wholesale & retail | 2026 |
| Auto Makeup Ltd | Wholesale & retail | 2016 |
| Auto Pool Ltd | Wholesale & retail | 2020 |
| Auto-Train Limited | Education | 2005 |
| Autogear (Ossett) Ltd | Wholesale & retail | 2003 |
| Autoglazing (UK) Limited | Wholesale & retail | 2003 |
| Autohaus Kern Service Ltd | Wholesale & retail | 2005 |