| Advanced Nationwide Auctions Limited | Information & communication | 2017 |
| Advanced Nationwide Holdings Limited | Financial services | 2024 |
| Advanced Nationwide Limited | Information & communication | 2021 |
| Advanced PAT Services Ltd | Manufacturing | 2022 |
| Advanced Process Limited | Construction | 2015 |
| Advanced Services Group Limited | Professional & scientific | 2015 |
| Advanced Skin Care Limited | Health & social care | 1999 |
| Advanced Technical Plastic Moulding Ltd | Manufacturing | 2011 |
| Advanced Tool and Design Limited | Manufacturing | 1969 |
| Advanced Training and Testing Ltd | Education | 2008 |
| Advanced Wastewater & Drainage Limited | Water & waste | 2002 |
| Advancedsolutionsworldwide Ltd | Construction | 2025 |
| Advancing Eyecare (UK) Limited | Financial services | 2025 |
| Advancing Holdings Limited | Financial services | 2015 |
| Advancing Limited | Administrative & support | 2011 |
| Advant-Edge Consulting Limited | Professional & scientific | 2021 |
| Advantage Auto Parts Limited | Wholesale & retail | 2011 |
| Advantage Care X Training Services | Hospitality | 2017 |
| Advantage Entertainment Distribution Limited | Wholesale & retail | 2002 |
| Advantage GAS Ltd | Construction | 2023 |
| Advantage Scholars Ltd | Administrative & support | 2016 |
| Advantage Security Limited | Administrative & support | 2018 |
| Advantage Technology | | 2001 |
| Advectec Limited | Transport & logistics | 2016 |
| Adveera Care Limited | Health & social care | 2023 |
| Advent Care Ltd | Health & social care | 2022 |
| Advent Electrical and Fire Services Limited | Administrative & support | 2019 |
| Advent Productions Ltd | Wholesale & retail | 2019 |
| Adventruss Limited | Real estate | 2020 |
| Adventure Healthcare Ltd | Health & social care | 2026 |
| Adverly Solutions Ltd | Information & communication | 2024 |
| Adverse Solutions Limited | Professional & scientific | 2018 |
| Adverti Ltd | Information & communication | 2026 |
| Advertico Limited | Information & communication | 2013 |
| Advertiser UK Limited | Extraterritorial | 2021 |
| Advik Technologies Limited | Manufacturing | 2023 |
| Advisor Marketing Limited | Professional & scientific | 2011 |
| Advocate Housing Limited | Hospitality | 2024 |
| Advocate Public Affairs (Midlands) Ltd | Professional & scientific | 2024 |
| ADW Data Solutions Ltd | Information & communication | 2024 |
| ADW Management & Investment Limited | Professional & scientific | 2025 |
| ADY Engineering & Recycling Solutions Ltd | Extraterritorial | 2018 |
| ADY Trading Ltd | Wholesale & retail | 2021 |
| Adyan-Uk Limited | Wholesale & retail | 2023 |
| ADZ International Limited | Wholesale & retail | 2020 |
| ADZ Investments Ltd | Real estate | 2022 |
| ADZ Real Estate Limited | Real estate | 2018 |
| AE & Co. Building Ltd | Construction | 2023 |
| AE Auto Enrolment Limited | Financial services | 2014 |
| AE Automotive Group Ltd | Wholesale & retail | 2026 |
| AE Compliance Ltd | Professional & scientific | 2026 |
| AE Events and Consultancy Ltd | Hospitality | 2024 |
| AE Residence Limited | Households | 2024 |
| Ae&Jo Ltd | Professional & scientific | 2023 |
| Ae&T Limited | Manufacturing | 1997 |
| AE43 Limited | Professional & scientific | 2017 |
| AEA Management Limited | Real estate | 2002 |
| AEC Removals Ltd | Transport & logistics | 2025 |
| Aeco Global Limited | Administrative & support | 2020 |
| Aecura Health Limited | Health & social care | 2026 |
| Aedesia Limited | Professional & scientific | 2014 |
| Aedesia Properties Limited | Professional & scientific | 2016 |
| Aedi Concept Limited | Professional & scientific | 2016 |
| Aedis Warranties Ltd | Financial services | 2014 |
| Aedova Group Limited | Water & waste | 2026 |
| AEE Renewables UK 29 Limited | Energy | 2011 |
| AEF Real Estates Ltd | Real estate | 2021 |
| Aegina Ltd | Construction | 2018 |
| Aegis Collective Limited | Administrative & support | 2024 |
| Aegis Group Shrewsbury Holdings Limited | Real estate | 2025 |
| Aegis Public Services Limited | Professional & scientific | 2026 |
| Aegon Kingston UK Ltd | Real estate | 2019 |
| AEL Fundco Limited | Real estate | 2004 |
| AEL Tuition Centre Ltd | Education | 2024 |
| AEL Tuition Ltd | Education | 2023 |
| AEM BST Ltd | Transport & logistics | 2025 |
| AEM Property Services Ltd | Construction | 2021 |
| AEN Holdings Limited | Wholesale & retail | 2022 |
| AEO Consulting Limited | Professional & scientific | 2002 |
| AEO Limited | Real estate | 2001 |
| Aeo-Rex Ltd | Professional & scientific | 2026 |
| Aeonium Limited | Extraterritorial | 2023 |
| Aequalis Education Trust | Education | 2016 |
| Aequitas (Oakengates) Ltd | Real estate | 2018 |
| Aequitas Malinslee Limited | Health & social care | 2020 |
| Aequitas Shifnal Ltd | Real estate | 2021 |
| Aequus Land (Dorrington) Ltd | Real estate | 2017 |
| Aequus Land Investments LLP | | 2018 |
| Aequus Land Ltd | Financial services | 2008 |
| Aeras Travel Limited | Transport & logistics | 2023 |
| Aerbio UK Ltd | Professional & scientific | 2024 |
| Aeren Ltd | Health & social care | 2020 |
| Aergia Ltd | Wholesale & retail | 2022 |
| Aergia Properties Limited | Real estate | 2018 |
| Aerial Visuals Limited | Information & communication | 2023 |
| Aeris Allergy Clinic Ltd | Health & social care | 2025 |
| Aeristech Control Technologies Ltd | Professional & scientific | 2010 |
| Aeristech Limited | Professional & scientific | 2006 |
| Aero BCC Limited | Wholesale & retail | 2025 |
| Aero Cars of Walsall Ltd | Transport & logistics | 2019 |