| ABL Property Solutions Ltd | Real estate | 2025 |
| Able & Baker Property Limited | Construction | 2020 |
| Ablrma Ltd | Transport & logistics | 2023 |
| Abode Academy Limited | Education | 2022 |
| Abode and Beyond Cleaning Ltd | Administrative & support | 2018 |
| Abode Showrooms Ltd | Wholesale & retail | 2022 |
| Abode Spray Supplies Ltd | Other services | 2020 |
| Abode Sprayers Limited | Wholesale & retail | 2024 |
| Above ALL Construction Limited | Construction | 2019 |
| Above Ground Construction Limited | Construction | 2006 |
| Abscarr Limited | Hospitality | 2023 |
| Absl Consulting Limited | Administrative & support | 2009 |
| Absolute Mustard Ltd. | Professional & scientific | 2024 |
| Absolutely Cleaning Services (Holdings) Limited | Financial services | 2020 |
| Absorbent Minds Holdings Limited | Administrative & support | 2011 |
| Absorbent Minds Ltd | Wholesale & retail | 2004 |
| Abundant Sun Limited | Professional & scientific | 2003 |
| Access to Climb CIC | Information & communication | 2024 |
| Access-It Software (UK) Limited | Information & communication | 2002 |
| Ace Body Worx Limited | Wholesale & retail | 2019 |
| Ace Elements UK Ltd | Financial services | 2025 |
| Ace Express Couriers Ltd | Transport & logistics | 2026 |
| Acme Labs Limited | Extraterritorial | 2018 |
| Acorn Architectural Ltd | Professional & scientific | 2015 |
| Acorn Computers (Cambridge) Limited | Manufacturing | 2009 |
| Acorn Tree & Landscapes Ltd | Administrative & support | 2026 |
| Acoustic Doors & Windows Ltd | Construction | 2014 |
| Acravia Limited | Real estate | 2025 |
| Acres Wild Forestry Ltd | Agriculture & fishing | 2024 |
| Acres Wild Woodlands Limited | Agriculture & fishing | 2009 |
| Actiondrome Limited | Administrative & support | 2007 |
| Active Governance Limited | Information & communication | 2026 |
| Active Insight Limited | Information & communication | 2022 |
| Active Plumbing Supplies (Calne) Limited | Wholesale & retail | 2009 |
| Actua Systems Limited | Manufacturing | 2012 |
| Actuaries for Lawyers (2013) Ltd | Financial services | 2012 |
| Actuation Technology Limited | Professional & scientific | 2013 |
| AD Ecology Ltd | Agriculture & fishing | 2011 |
| AD Paving Limited | Construction | 2018 |
| Ad-Rains Limited | Extraterritorial | 2008 |
| Adam and EVE Property Care Chippenham Ltd | Administrative & support | 2020 |
| Adam Bailey Limited | Wholesale & retail | 2007 |
| Adam Bailey Properties Limited | Real estate | 2017 |
| Adamo Lifestyle Ltd | Construction | 2020 |
| Adamo UK Living Ltd | Construction | 2021 |
| Adaptomic Ltd | Information & communication | 2019 |
| Adato Ltd | Manufacturing | 2019 |
| Adawall Limited | Extraterritorial | 2017 |
| ADB Carpentry & Sons Ltd | Construction | 2023 |
| Adendale Limited | Professional & scientific | 2006 |
| Adept Partners Group Limited | Administrative & support | 2020 |
| Adept PM Holdings Limited | Real estate | 2019 |
| Adi's Autos Limited | Administrative & support | 2010 |
| ADL Trading Limited | Construction | 2003 |
| Adorable Dogs Ltd | Administrative & support | 2006 |
| ADP Education Support Services Ltd | Education | 2026 |
| Advanced Paints Western Ltd | Wholesale & retail | 2013 |
| Advanced Systems Understanding Trustee Limited | Financial services | 2022 |
| Adventure Pursuits Limited | Arts & recreation | 2016 |
| Adzzip Ltd | Financial services | 2019 |
| Aegros Bidco Limited | Financial services | 2024 |
| Aegros Holdco 1 Limited | Financial services | 2024 |
| Aegros Holdco 2 Limited | Financial services | 2024 |
| Aegros Holdco 3 Limited | Financial services | 2024 |
| Aeschylus Limited | Construction | 1984 |
| Aesum Limited | Administrative & support | 2017 |
| Aesum Property Developments Ltd | Real estate | 2024 |
| Aethelstans Outfitters Limited | Wholesale & retail | 2022 |
| AF Windows Limited | Administrative & support | 2009 |
| Affecton Accounting Limited | Professional & scientific | 2019 |
| Affecton Limited Liability Partnership | | 2002 |
| Afianco Limited | Professional & scientific | 2023 |
| Afya Global Ltd | Professional & scientific | 2012 |
| AG Electrical Consultants Limited | Administrative & support | 2013 |
| AG Executive Transport Ltd | Transport & logistics | 2019 |
| AG Vehicle Repairs & Diagnostics Ltd | Wholesale & retail | 2026 |
| Agriplant Sales and Leasing Ltd | Wholesale & retail | 2025 |
| Agrispares (UK) Ltd | Other services | 2003 |
| AGT Farms Limited | Agriculture & fishing | 2017 |
| Ahead of the Crowd Limited | Real estate | 2011 |
| AIM Enterprises Limited | Wholesale & retail | 2018 |
| Ainoso Ltd | Information & communication | 2025 |
| Air Cooled Services Limited | Extraterritorial | 2022 |
| Airdrawn Limited | Information & communication | 2024 |
| Airdrawn Works Limited | Information & communication | 2025 |
| Aitken Strategies Limited | Financial services | 2025 |
| Aixon Digital Limited | Information & communication | 2024 |
| AJ Cleaning (Bristol) Ltd | Administrative & support | 2024 |
| AJ Plumbing and Heating Services Ltd | Construction | 2019 |
| AJ Security Bristol Ltd | Administrative & support | 2019 |
| AJ Security South West Ltd | Administrative & support | 2024 |
| AJ Wright (Electrical) Limited | Construction | 2007 |
| AJB Farming Ltd | Agriculture & fishing | 1997 |
| AJN Educational Consultancy Limited | Education | 2015 |
| AJT Prestige Ltd | Health & social care | 2021 |
| AJW Heating Ltd | Construction | 2015 |
| AK Properties Limited | Real estate | 2017 |
| Akash (Chippenham) Limited | Hospitality | 2002 |
| Akwel Birmingham UK Limited | Manufacturing | 1997 |
| AL Arafah Groceries Ltd | Wholesale & retail | 2024 |