| Abruzzo Truffles Limited | Wholesale & retail | 2016 |
| ABS Community Care Ltd | Transport & logistics | 2026 |
| ABS Home Services Limited | Administrative & support | 2006 |
| ABS Social Care Transport Ltd | Transport & logistics | 2026 |
| ABS South Eastern Limited | Construction | 2003 |
| Absolute FS Building Management Ltd | Administrative & support | 2021 |
| Absolute Protection Group Ltd | Construction | 2017 |
| Absolute Renewables Limited | Construction | 2025 |
| Absw Limited | Other services | 2010 |
| Abundify Ltd | Wholesale & retail | 2026 |
| Abwabco Ltd | Health & social care | 2022 |
| Abzolute Limited | Professional & scientific | 2012 |
| AC Carpentry and Building Limited | Manufacturing | 2022 |
| AC Kitchens & Bathrooms Ltd | Construction | 2015 |
| AC Timber Structures Ltd | Construction | 2017 |
| ACA Mechanical Ltd | Manufacturing | 2024 |
| ACC Commercial Cleaning Limited | Administrative & support | 2023 |
| Access Buzzers Limited | Construction | 2014 |
| Access Futures CIC | Administrative & support | 2015 |
| Accessible Resource Library CIC | Education | 2024 |
| Acclivity Project Services Ltd | Professional & scientific | 2024 |
| ACCOUNT4ME Limited | Professional & scientific | 2022 |
| Accounting Solutions Practice Ltd | Professional & scientific | 2011 |
| Accra Services Hub Limited | Wholesale & retail | 2026 |
| Accs Technical Services Ltd | Construction | 2012 |
| Accsys Accountants Limited | Professional & scientific | 2007 |
| Accurate Fire Solutions Ltd | Public administration | 2020 |
| Accurate Homes Limited | Real estate | 2020 |
| Ace Capital Estates Ltd | Real estate | 2024 |
| Ace High Residents Management Limited | Households | 2017 |
| Ace Point Travel Limited | Administrative & support | 2005 |
| Ace Sports Store Ltd | Wholesale & retail | 2023 |
| Ace Staff Ltd | Administrative & support | 2021 |
| Ace Technology Holdings Limited | Wholesale & retail | 2009 |
| Ace Virtual Assistant Services Ltd | Transport & logistics | 2022 |
| Acedd Service Ltd | Health & social care | 2022 |
| Acer Property Limited | Households | 2004 |
| Acewood Limited | Construction | 1988 |
| ACF Construction Limited | Construction | 2025 |
| Achievable Safety Ltd | Professional & scientific | 2020 |
| Achilles Decorating Ltd | Construction | 2021 |
| Acitiy Ltd | Wholesale & retail | 2021 |
| ACL Automotive Contracts Ltd | Administrative & support | 2007 |
| ACL Automotive Ltd | Administrative & support | 2010 |
| ACM Electrical Solutions Ltd | Construction | 2023 |
| ACM Print Management Limited | Manufacturing | 2017 |
| ACM South East Ltd | Households | 2012 |
| Acorn Builders Haslemere Ltd | Construction | 2016 |
| Acorn Developments (Haslemere) Ltd | Real estate | 2016 |
| Acorn Groundwork Limited | Construction | 1999 |
| Acoustic Advice Ltd | Construction | 2018 |
| Acoustic Sales Limited | Construction | 2003 |
| Acovia Ltd | Information & communication | 2017 |
| ACP Engineering Limited | Manufacturing | 2020 |
| Acre 1 Limited | Hospitality | 2023 |
| Acre 2 Limited | Hospitality | 2023 |
| Acre Events Limited | Other services | 2023 |
| Acres Holdings Limited | Real estate | 2019 |
| Acres Landscaping & Maintenance Limited | Real estate | 2002 |
| Across Magazines Limited | Wholesale & retail | 1986 |
| ACS Legal Limited | Professional & scientific | 2013 |
| ACT (Holdings) Kent Limited | Financial services | 2023 |
| ACT Transport Ltd | Transport & logistics | 2023 |
| Actiondesk Ltd | Professional & scientific | 2025 |
| Active Care Wellbeing Limited | Health & social care | 2024 |
| Active Substances Limited | Wholesale & retail | 2015 |
| Acton Warner Limited | Construction | 2017 |
| Actors International Limited | Arts & recreation | 2000 |
| Acuit Investments Ltd | Households | 2020 |
| Acuit Ltd | Professional & scientific | 2019 |
| Aculinx Limited | Professional & scientific | 2001 |
| Acute Productions Ltd | Information & communication | 2023 |
| AD 2000 Windows Limited | Construction | 1997 |
| AD Chester Limited | Energy | 2015 |
| AD Electrical & Security Limited | Construction | 2018 |
| AD Installations & Contracting Limited | Energy | 2010 |
| AD1 Holdings Limited | Financial services | 2025 |
| ADA Live Limited | Professional & scientific | 2024 |
| Adalya Group Ltd | Administrative & support | 2025 |
| Adalya Homes Ltd | Real estate | 2025 |
| Adam Developer Ltd | Professional & scientific | 2024 |
| Adam Eckley Services Limited | Professional & scientific | 2019 |
| Adam Loveday-Brown Ltd | Information & communication | 2024 |
| Adams & Co Builders Ltd | Construction | 2017 |
| Adams & Rees Properties Limited | Construction | 2026 |
| Adams Creative Group Limited | Information & communication | 2016 |
| Adams Property Maintenance Limited | Administrative & support | 2023 |
| Adaptive Motorhome Hire Ltd | Administrative & support | 2024 |
| Adasa Group Ltd | Real estate | 2023 |
| Adave Ltd | Health & social care | 2013 |
| ADC Security Ltd | Construction | 2014 |
| Adcity UK Limited | Professional & scientific | 2015 |
| Adecity Cakes & Events Ltd | Hospitality | 2021 |
| Adeem Ltd | Real estate | 2017 |
| Adela Aesthetics Ltd | Other services | 2023 |
| Adelia Services Ltd | Construction | 2025 |
| Adelizem Ltd | Wholesale & retail | 2021 |
| Adhd Transitions Ltd | Education | 2024 |
| ADI11 Ltd | Other services | 2015 |
| Adidom Transport Ltd | Transport & logistics | 2023 |