| Acceron Ltd | Information & communication | 2020 |
| Accesa Alliance PC | | 2019 |
| Accespeak Ltd | Information & communication | 2026 |
| Access Maintenance (UK) Ltd | Real estate | 2014 |
| Access and Value Writing Limited | Professional & scientific | 2023 |
| Access Care 24 Ltd | Health & social care | 2022 |
| Access Garage Doors (South Wales) Limited | Manufacturing | 2008 |
| Access Group Industrial Services Limited | Construction | 2015 |
| Access Hire and Sales Ltd | Construction | 2013 |
| Access HR Solutions Ltd | Administrative & support | 2021 |
| Access Included Limited | Professional & scientific | 2004 |
| Access Into Medicine Limited | Education | 2019 |
| Access Medical Cannabis UK Ltd | Health & social care | 2025 |
| Access Mentors Ltd | Other services | 2020 |
| Accessit Technical Services Ltd | Administrative & support | 2021 |
| Accipiter Designs Limited | Professional & scientific | 1987 |
| Accociation Tapper Ltd | Wholesale & retail | 2026 |
| Accomplished Accountancy Ltd | Professional & scientific | 2014 |
| Accord Training and Development Ltd | Education | 2021 |
| Accorda Ltd | Professional & scientific | 2014 |
| Accordion Innovation Ltd | Information & communication | 2022 |
| Accountability Cardiff Limited | Professional & scientific | 2014 |
| Accountants and Taxx Ltd | Construction | 2022 |
| Accountants ETC Ltd | Professional & scientific | 2018 |
| Accountaxify Ltd | Professional & scientific | 2020 |
| Accounted for Limited | Professional & scientific | 2006 |
| Accountgro Ltd | Professional & scientific | 2026 |
| Accounting Angles Limited | Professional & scientific | 2018 |
| Accounts Keeper Limited | Administrative & support | 2016 |
| Accounts on Point Limited | Professional & scientific | 2018 |
| Accru Scenic Construction Limited | Construction | 2015 |
| Accuk Marketing Services Ltd | Administrative & support | 2020 |
| Accura Engineering Solutions Limited | Manufacturing | 2014 |
| Accurate Recruiting Ltd | Administrative & support | 2021 |
| ACD3.AI Consulting Ltd | Professional & scientific | 2026 |
| Acdc Engineering Ltd | Professional & scientific | 2025 |
| Ace Alloys Ltd | Wholesale & retail | 2017 |
| Ace Cardiff Limited | Education | 2006 |
| Ace Care Homes Ltd | Health & social care | 2025 |
| Ace Cars Berkhamsted Limited | Transport & logistics | 2016 |
| Ace Community Enterprises Limited | Health & social care | 2014 |
| Ace Construction Equipment Ltd | Administrative & support | 2016 |
| Ace Consultancy Services Limited | Health & social care | 2003 |
| Ace Corporation Limited | Professional & scientific | 2025 |
| Ace Debt Recovery Ltd | Administrative & support | 2024 |
| Ace Delivery Solutions Ltd | Administrative & support | 2016 |
| Ace Essential Supplies (Trading) Limited | Wholesale & retail | 2010 |
| Ace Essential Supplies Holdings Limited | Financial services | 2022 |
| Ace Essential Supplies Limited | Real estate | 2005 |
| Ace Feet in Motion Ltd | Health & social care | 2015 |
| Ace Gaming Limited | Information & communication | 2005 |
| Ace Glazed Products Limited | Construction | 2002 |
| Ace Global Marketers Ltd | Wholesale & retail | 2020 |
| Ace Global Suppliers Ltd | Administrative & support | 2021 |
| Ace Golf Club Hire Ltd | Arts & recreation | 2015 |
| Ace Holdings (UK) Limited | Information & communication | 2005 |
| Ace Initiatives Ltd | Construction | 2021 |
| Ace MOT Station Limited | Wholesale & retail | 2014 |
| Ace Movers and Storage Ltd | Transport & logistics | 2024 |
| Ace Orthotics Limited | Manufacturing | 2000 |
| Ace Personal Safety Awareness & Nutrition Ltd | Public administration | 2019 |
| Ace Portable Accommodation Limited | Hospitality | 2003 |
| Ace Project & Operations Consulting Ltd | Real estate | 2025 |
| Ace Rigging and Lifting Services Ltd | Professional & scientific | 2015 |
| Ace to College Ltd | Arts & recreation | 2025 |
| Ace Working Holidays Limited | Hospitality | 2016 |
| Ace'D IT Salon Ltd | Other services | 2019 |
| Ace-Action in Caerau and ELY | Health & social care | 2011 |
| Ace-Co Limited | Professional & scientific | 2018 |
| ACE888 Media Ltd | Wholesale & retail | 2025 |
| Acequ International Limited | Professional & scientific | 2019 |
| Aces Tattoo Studio Ltd | Arts & recreation | 2023 |
| Acesos Holdings Ltd | Professional & scientific | 2019 |
| Acetrendz Ltd | Wholesale & retail | 2024 |
| Aceyfrederi Limited | Agriculture & fishing | 2023 |
| ACG Construct Ltd | Manufacturing | 2019 |
| ACG Padel Ltd | Education | 2025 |
| ACG Trading Ltd | Administrative & support | 2010 |
| ACH Cardiff Ltd | Wholesale & retail | 2020 |
| ACH Trading Ltd | Other services | 2024 |
| Acha Group Ltd | Transport & logistics | 2019 |
| Achd Ltd | Wholesale & retail | 2020 |
| Achievecoco Ltd | Information & communication | 2018 |
| Achieving Sustainable Change Ltd | Professional & scientific | 2012 |
| Achilleus Security (North) Limited | Administrative & support | 2019 |
| Achromatichome Ltd | Wholesale & retail | 2021 |
| ACI Consultants Ltd | Education | 2020 |
| ACI Transport Ltd | Transport & logistics | 2017 |
| Acik Food Ltd | Hospitality | 2019 |
| Ackaba Ltd | Information & communication | 2021 |
| Ackers Holdings Ltd | Real estate | 2016 |
| Ackland Law Limited | Professional & scientific | 2021 |
| ACL Wholesale Limited | Wholesale & retail | 2018 |
| Acland Three Ltd | Construction | 2023 |
| Acmc Europe Ltd | Wholesale & retail | 2016 |
| Acme FC Ltd | Hospitality | 2025 |
| Acme United (Group) Limited | Transport & logistics | 1935 |
| Acmo Izoterm Ltd | Transport & logistics | 2024 |
| ACN Properties Limited | Real estate | 2020 |
| ACN Property Investments Ltd | Real estate | 2024 |