| Accounting Services Warrington Ltd | Professional & scientific | 2012 |
| Accrapak Systems Limited | Manufacturing | 1976 |
| Accupower Limited | Professional & scientific | 2017 |
| Acdb Solutions Limited | Other services | 2018 |
| Ace Advantage Ltd | Professional & scientific | 2025 |
| Ace Construction Management Limited | Administrative & support | 2013 |
| Ace Consulting Services Ltd | Real estate | 2000 |
| Ace Fire Safety Ltd | Professional & scientific | 2025 |
| Ace Fire Services Ltd | Manufacturing | 2020 |
| Ace Logistics (Warrington) Ltd | Transport & logistics | 2024 |
| Ace Mobile Mechanics Ltd | Wholesale & retail | 2012 |
| Ace Projects Group Ltd | Construction | 2026 |
| Ace Properties & Events Limited | Other services | 2016 |
| Ace-Business Ltd | Information & communication | 2018 |
| Achg Ltd | Administrative & support | 2023 |
| Achieve Safety Ltd. | Administrative & support | 2008 |
| Achilles Consultancy Services Ltd | Professional & scientific | 2018 |
| ACI Fleet Services Ltd | Wholesale & retail | 2019 |
| Acid Nerve Limited | Information & communication | 2014 |
| Ackc Ltd | Professional & scientific | 2010 |
| ACL Property North Limited | Real estate | 2025 |
| ACM Software Solutions Limited | Information & communication | 2019 |
| Acme Surplus Limited | Wholesale & retail | 2008 |
| ACO Services Limited | Construction | 2022 |
| ACO Signalling Ltd | Transport & logistics | 2024 |
| Acore Project Management and Consultancy Ltd | Construction | 2020 |
| Acorn Building Projects Ltd | Construction | 2009 |
| Acorn Doorsets Limited | Wholesale & retail | 2004 |
| Acorn Leisure NW Limited | Manufacturing | 2023 |
| Acorn Property Management Limited | Real estate | 1994 |
| ACORN2OAK Innovation Solutions Limited | Manufacturing | 2008 |
| Acquaintia Limited | Information & communication | 2026 |
| Acquiesce Training Ltd | Administrative & support | 2013 |
| ACR Aviation Capacity Resources UK Ltd | Transport & logistics | 2025 |
| Acre Technical Media Ltd | Administrative & support | 2025 |
| Acre Transportation Group Limited | Administrative & support | 2017 |
| Across Industrial Doors Ltd | Manufacturing | 2020 |
| Across the Pond Revenue Solutions Limited | Professional & scientific | 2023 |
| ACS Cleaning (Hull) Limited | Administrative & support | 2017 |
| ACS Electrics Limited | Construction | 2007 |
| Acspeedtech Ltd | Wholesale & retail | 2011 |
| Act-Ai Limited | Professional & scientific | 2025 |
| Acti-Petfoods Ltd | Wholesale & retail | 2021 |
| Actikem Ltd | Manufacturing | 2002 |
| Actinum Limited | Professional & scientific | 2017 |
| Action Cheshire CIC | Education | 2015 |
| Action Reclaim Ltd | Professional & scientific | 2016 |
| Activated Assets Group Ltd | Information & communication | 2026 |
| Active Dental Laboratory Ltd | Health & social care | 2010 |
| Active Electric Ltd | Administrative & support | 2025 |
| Active Hope Limited | Arts & recreation | 2011 |
| Active Surfaces Ltd | Construction | 2017 |
| Activity Angels CIC | Health & social care | 2024 |
| Acton Brickwork Ltd | Construction | 2021 |
| Acton Green Barns Management Company Limited | Households | 2025 |
| Actrov Ltd | Administrative & support | 2021 |
| Acts Sound & Lighting Limited | Arts & recreation | 2012 |
| Actualitas Limited | Professional & scientific | 2019 |
| Acuity Origin Limited | Information & communication | 2023 |
| Acumen Clinical Services, Research and Innovation Ltd | Health & social care | 2022 |
| Acumen Distribution Services Holdings Limited | Extraterritorial | 1997 |
| Acuo Ltd | Health & social care | 2015 |
| Acupointcare Limited | Wholesale & retail | 2025 |
| Acupuncture & Herbs Limited | Health & social care | 2002 |
| Acute Need Care and Support Limited | Professional & scientific | 2012 |
| Acute Need CIC | Health & social care | 2011 |
| Acute Projects Limited | Construction | 2011 |
| AD Bodytech Health & Nutrition Limited | Wholesale & retail | 2019 |
| AD Brierley Engineering Limited | Administrative & support | 2016 |
| AD Design Services Limited | Professional & scientific | 2025 |
| AD Gardening Services Ltd | Administrative & support | 2026 |
| AD Jones Consulting Limited | Professional & scientific | 2012 |
| AD Platt Residential Ltd | Real estate | 2020 |
| Adagietto Property Ltd | Real estate | 2023 |
| Adam James Davies Ltd | Professional & scientific | 2025 |
| Adam&Ewa Transport Ltd | Transport & logistics | 2014 |
| Adams BIO Consulting Limited | Other services | 2018 |
| Adams ES Ltd | Professional & scientific | 2025 |
| Adamson Lettings & Property Management Ltd | Real estate | 2013 |
| Adamsrill Ltd | Construction | 2017 |
| Adamszen Limited | Administrative & support | 2009 |
| Adana 1453 Limited | Hospitality | 2025 |
| Adapt Formwork Holdings Limited | Administrative & support | 2013 |
| Adapt Formwork Investments Limited | Administrative & support | 2018 |
| Adapt Formwork Limited | Administrative & support | 2009 |
| Adaptive Arts Ltd | Manufacturing | 2024 |
| Adas Consulting Ltd. | Administrative & support | 2016 |
| Adco Investments Limited | Financial services | 2018 |
| ADD Mobility Ltd | Manufacturing | 2022 |
| ADD More Zest Ltd | Wholesale & retail | 2021 |
| ADD Value Limited | Information & communication | 2019 |
| Added Lightness Limited | Professional & scientific | 2017 |
| Addicorp Limited | Administrative & support | 2013 |
| Addison Forming Technologies Limited | Manufacturing | 2012 |
| Addmix Concrete Limited | Manufacturing | 2012 |
| Adeam Investments Limited | Real estate | 2020 |
| Adele Carr Recruitment (EOT) Limited | Extraterritorial | 2022 |
| Adele Carr Recruitment Limited | Administrative & support | 2006 |
| Adelphi Services Limited | Administrative & support | 2009 |
| Adentt Medical Ltd | Health & social care | 2021 |