| Acer Healthcare Operations Limited | Health & social care | 2016 |
| Acer Sales Ltd | Wholesale & retail | 2013 |
| Acerbi & Villani Limited | Information & communication | 2012 |
| Aceso Health & Group Risk Limited | Extraterritorial | 2021 |
| Acet-Uk Ltd | Education | 2020 |
| ACH Global Ltd | Real estate | 2018 |
| Achd Group Ltd | Hospitality | 2023 |
| Achieve International Education Group Ltd | Education | 2025 |
| Achieve Search Ltd | Administrative & support | 2024 |
| Achieve Support Services Limited | Health & social care | 2014 |
| Achrl Care and Consultancy Ltd | Construction | 2026 |
| ACI Technical Solutions Limited | Administrative & support | 2011 |
| Acid Frog Ltd | Information & communication | 2009 |
| Acina Commercial Ltd | Construction | 2022 |
| Acjc Ltd | Real estate | 2023 |
| Ackan Recruitment Limited | Administrative & support | 2024 |
| Ackroyd Street Management Company Limited | Real estate | 2006 |
| Ackworth Park Farm Management Company Limited | Households | 2016 |
| ACL Estates Limited | Construction | 2004 |
| ACL Residential Limited | Construction | 2020 |
| ACL Smart MOD Ltd | Wholesale & retail | 2025 |
| ACM Structural Ltd | Professional & scientific | 2018 |
| ACM Tooling UK Ltd | Manufacturing | 2024 |
| Acma-Med Limited | Professional & scientific | 2023 |
| Acmt Surgery Limited | Health & social care | 2011 |
| Acoda Ltd | Professional & scientific | 2023 |
| Acolink Ltd | Wholesale & retail | 2015 |
| Aconpex (UK) Limited | Manufacturing | 1990 |
| Acorn Academy (Leeds) Limited | Education | 2023 |
| Acorn Autos Limited | Wholesale & retail | 2007 |
| Acorn Bathrooms Limited | Manufacturing | 1989 |
| Acorn BS Services Ltd | Administrative & support | 2018 |
| Acorn Business Centres (Grimsby) Limited | Real estate | 1989 |
| Acorn Business Centres (Killingbeck) Limited | Real estate | 1988 |
| Acorn Business Centres (Yeadon) Limited | Real estate | 1989 |
| Acorn Construction (Yorkshire) Ltd. | Construction | 1996 |
| Acorn Event Solutions Ltd | Construction | 2006 |
| Acorn Family Investments Unlimited | Financial services | 2021 |
| Acorn GAS Appliance Spares Limited | Wholesale & retail | 2000 |
| Acorn Inventories Limited | Administrative & support | 2014 |
| Acorn Projects (Yorkshire) Ltd | Construction | 2018 |
| Acorn Property Development Limited | Real estate | 1995 |
| Acorn Scaffolding (Yorkshire) Ltd | Construction | 1998 |
| Acoro Medical Limited | Manufacturing | 2023 |
| Acoustic Installations Limited | Construction | 1993 |
| Acquda Limited | Administrative & support | 2021 |
| Acquire Capital Ltd | Professional & scientific | 2017 |
| Acquirity Limited | Professional & scientific | 2020 |
| Acquiro Digital Ltd | Information & communication | 2018 |
| Acquisista Ltd | Real estate | 2022 |
| ACR (2020) Ltd | Households | 2021 |
| ACR Bodyworks Ltd | Wholesale & retail | 2025 |
| ACR Composites Limited | Manufacturing | 2016 |
| Acrab Electricals Limited | Construction | 2019 |
| Acre UK Properties Limited | Real estate | 2018 |
| ACRES22.COM Limited | Professional & scientific | 2024 |
| Acrivarn Group Holdings Limited | Financial services | 2024 |
| Acrivarn Limited | Manufacturing | 1967 |
| Acropolis Mediterranean Restaurant Limited | Hospitality | 2020 |
| ACS BP Holdings Limited | Financial services | 2018 |
| ACS Building Products Limited | Manufacturing | 2015 |
| ACS Facades Holdings Limited | Financial services | 2019 |
| ACS Facades Limited | Manufacturing | 2019 |
| ACS Stainless Limited | Manufacturing | 2015 |
| ACS Stainless Steel Fixings Limited | Manufacturing | 1984 |
| ACS Yorkshire Limited | Wholesale & retail | 2020 |
| ACT Finance Limited | Professional & scientific | 2011 |
| ACT for Yorkshire Ltd | Health & social care | 2011 |
| ACT II Scene VII Films Ltd | Information & communication | 2018 |
| Acti-Ve Qaqc Consultants Ltd | Professional & scientific | 2023 |
| Action Care & Support Ltd | Health & social care | 2026 |
| Action Care Management Ltd | Administrative & support | 2018 |
| Action Facilities & Management Ltd | Construction | 2026 |
| Action on Access Information Services Limited | Education | 2022 |
| Action Property Management Limited | Real estate | 2007 |
| Action Pumps Limited | Wholesale & retail | 1998 |
| Actionprompt Limited | Hospitality | 2008 |
| Actius (International) Limited | Extraterritorial | 2011 |
| Active (Pathways) Solutions Ltd | Administrative & support | 2023 |
| Active Alert Ltd | Construction | 2023 |
| Active Branding Limited | Professional & scientific | 2006 |
| Active Cleaning Limited | Administrative & support | 2002 |
| Active Cleaning Solutions Limited | Administrative & support | 2002 |
| Active Future West Leeds Ltd | Education | 2024 |
| Active Guards & FM Ltd | Administrative & support | 2016 |
| Active Kids (Yeadon) LLP | | 2008 |
| Active Lifestyle Protection Ltd | Professional & scientific | 2008 |
| Active Live 7 CIC | Education | 2026 |
| Active Print Solutions Limited | Manufacturing | 2003 |
| Active Properties (Leeds) Limited | Real estate | 2014 |
| Active Source UK Leeds Ltd | Wholesale & retail | 2026 |
| Activepoint UK Limited | Information & communication | 2013 |
| Activewheel UK Limited | Real estate | 2025 |
| Acts Group Limited | Professional & scientific | 2004 |
| Acts of Light Ltd | Hospitality | 2025 |
| Actts Logistics Limited | Transport & logistics | 2019 |
| Actual IT Solutions Ltd. | Information & communication | 2004 |
| Actual U Ltd | Other services | 2024 |
| Acuity Robotics Limited | Professional & scientific | 2019 |
| Acumen HR Services Ltd | Administrative & support | 2018 |