| ACG Rehab Ltd | Other services | 2024 |
| ACH 2025 Holdings Limited | Financial services | 2025 |
| Achieve Outreach Ltd | Education | 2020 |
| Achievedarajat Ltd | Education | 2026 |
| Achour Property Ltd | Real estate | 2020 |
| ACK (Holdings) Limited | Professional & scientific | 2014 |
| ACL Procurement Ltd | Professional & scientific | 2020 |
| Acodent Limited | Manufacturing | 2014 |
| Acolet Global Ltd | Construction | 2011 |
| Acom Supplies Limited | Wholesale & retail | 2025 |
| Acon Cleaning Services Ltd | Administrative & support | 2025 |
| Acook Consultancy Ltd | Information & communication | 2016 |
| Acorn Academies Limited | Extraterritorial | 2011 |
| Acorn Academy of Direct Learning Limited | Education | 2019 |
| Acorn Care & Education (OPS) Ltd | Professional & scientific | 2009 |
| Acorn Care and Education Limited | Professional & scientific | 2004 |
| Acorn Education and Care Services Ltd | Education | 2009 |
| Acorn Investments BVI Limited | Other services | 2023 |
| Acorn Land Planning Limited | Other services | 2018 |
| Acorn Norfolk Limited | Education | 2010 |
| Acorn Plant Hire Limited | Administrative & support | 2014 |
| Acorn Polymers (U.K.) Ltd | Manufacturing | 1998 |
| Acornwood Limited | Real estate | 2022 |
| Acow Limited | Wholesale & retail | 2022 |
| Acquiesce Group Ltd | Financial services | 2026 |
| Acquiesce Holdings Ltd | Financial services | 2022 |
| Acquiesce Ltd | Health & social care | 2017 |
| Acquire Business Sales Ltd | Other services | 2012 |
| Acquired Assessment Limited | Information & communication | 2003 |
| Acquisition Investments Ltd | Real estate | 2025 |
| ACR Properties Limited | Real estate | 2021 |
| Acraman 514 Limited | Administrative & support | 2017 |
| Acresdale Allen ST Ltd | Real estate | 2021 |
| Acresdale Investments Limited | Real estate | 2018 |
| Acresfield Developments Limited | Professional & scientific | 2016 |
| Acseu Ltd | Administrative & support | 2019 |
| Acsuk Co Ltd | Administrative & support | 2009 |
| ACT Pharma Limited | Health & social care | 2022 |
| Actfastresources Limited | Administrative & support | 2023 |
| Actinvite Limited | Administrative & support | 2023 |
| Action & Change Ltd | Professional & scientific | 2024 |
| Action and Achieve Limited | Professional & scientific | 2020 |
| Active Bolton Ltd. | Arts & recreation | 2001 |
| Active Dancewear Limited | Wholesale & retail | 2009 |
| Active Pipeline Refurbishment Technologies Ltd | Manufacturing | 2003 |
| Activedance Spirals Ltd | Administrative & support | 2012 |
| Actor Tribe Limited | Arts & recreation | 2013 |
| Actuarial Enterprise Solutions Limited | Professional & scientific | 2014 |
| Acuity Stream Limited | Professional & scientific | 2018 |
| Acumen Infotech Ltd | Information & communication | 2008 |
| Acurtis Electrical Services Limited | Construction | 2025 |
| Acute Ambulance & Medical Services Limited | Health & social care | 2007 |
| Acute Consulting Services Ltd | Other services | 2020 |
| AD 01 Limited | Financial services | 2015 |
| AD Cleaning Solutions Ltd | Administrative & support | 2025 |
| AD Collective Ltd | Professional & scientific | 2025 |
| AD Foods (Bolton) Ltd | Hospitality | 2024 |
| AD Infinitum Consulting Limited | Professional & scientific | 2024 |
| AD Investments Ltd | Real estate | 2013 |
| AD IT Systems Limited | Information & communication | 2018 |
| AD Nova Digital Ltd | Information & communication | 2026 |
| AD Safety Management(Nw) Ltd | Construction | 2019 |
| AD Windows Ltd | Construction | 2025 |
| ADA Plans and Architectural Services Ltd | Professional & scientific | 2019 |
| Adalta Development Ltd | Professional & scientific | 2003 |
| Adam & Co Accountants Limited | Professional & scientific | 2008 |
| Adam & J Limited | Administrative & support | 2021 |
| Adam Ariff Coaching Ltd | Education | 2021 |
| Adam Brett Consulting Limited | Professional & scientific | 2022 |
| Adam DIY & Plumbing Limited | Wholesale & retail | 2025 |
| Adam Essap Holdings Ltd | Financial services | 2022 |
| Adam J Mcgilvery Consulting Ltd | Education | 2009 |
| Adam Lawson Joinery Limited | Construction | 2017 |
| Adam Miah T/A Smash Box Ltd | Hospitality | 2026 |
| Adam Mini Mart Limited | Wholesale & retail | 2019 |
| Adam Pharma Ltd | Wholesale & retail | 2024 |
| Adam PHS Limited | Construction | 2017 |
| Adam Properties North West Ltd | Households | 2023 |
| Adam Riley Ltd | Hospitality | 2025 |
| Adam Southern Kitchens Ltd | Construction | 2021 |
| Adam Tara Limited | Hospitality | 2025 |
| Adam W Consultancy Limited | Financial services | 2024 |
| Adamaris Ltd | Wholesale & retail | 2021 |
| Adams & Co Accountants Limited | Financial services | 2021 |
| Adams & Co UK Ltd | Other services | 2016 |
| Adams Pro DRY Cleaners Ltd | Other services | 2025 |
| Adams Selfstore LLP | | 2003 |
| Adams Transport Services Ltd | Transport & logistics | 2025 |
| Adamsons Consultancy Ltd | Professional & scientific | 2011 |
| Adam’S Patisserie Ltd | Manufacturing | 2025 |
| Adapt Performance LAB Ltd | Wholesale & retail | 2026 |
| Adapt PM Limited | Real estate | 2025 |
| Adapt Professional Ltd | Information & communication | 2023 |
| Adaptive Consultancy Limited | Professional & scientific | 2023 |
| Adaptive Meshnet Ltd | Manufacturing | 2026 |
| Adaptool Ltd | Professional & scientific | 2020 |
| Adboards Limited | Manufacturing | 1982 |
| Added Development Limited | Real estate | 2025 |
| Addergoole Consultancy Ltd | Construction | 2024 |
| Adderstone Mansion Management Co Limited | Real estate | 1998 |