| Agriblu Limited | Agriculture & fishing | 2025 |
| Agricomms International Ltd | Wholesale & retail | 2022 |
| Agricultural, Forestry Services & Developments Limited | Construction | 2006 |
| Agrivision Technology Ltd | Information & communication | 2024 |
| Agua Tech Ltd | Manufacturing | 2019 |
| Aibizzapps Limited | Information & communication | 2025 |
| Aircon Projects Limited | Administrative & support | 2024 |
| AJA Investment Limited | Real estate | 2022 |
| AJB Property & Development Ltd | Real estate | 2021 |
| Ajdw Consultancy Limited | Professional & scientific | 2008 |
| AJP Plumbing & Heating Ltd | Construction | 2014 |
| AJT Education Limited | Education | 2013 |
| AJT Ventures Limited | Education | 2024 |
| Akkus 63 Limited | Hospitality | 2025 |
| Akriveia Ltd | Professional & scientific | 2020 |
| Alacrity Limited | Professional & scientific | 2014 |
| Alan Renwick Wealth Management Limited | Financial services | 2014 |
| Alanjuna 22 Ltd | Administrative & support | 2022 |
| Alaska Property Ltd | Real estate | 2016 |
| Albemarle Proma Limited | Construction | 2019 |
| ALC Construction and Development Limited | Construction | 2012 |
| Alderson Mews Management Company Ltd | Households | 2025 |
| Aldoc Ltd | Manufacturing | 2012 |
| ALE Festival UK Ltd | Extraterritorial | 2012 |
| Alec Ltd | Health & social care | 2024 |
| Alec Quarton Electrical Limited | Construction | 2012 |
| Aleon Limited | Professional & scientific | 2013 |
| Alessandro Caruso Architecture and Interiors Limited | Professional & scientific | 2014 |
| Alexander Ellis Ltd | Wholesale & retail | 2011 |
| Aligor Limited | Real estate | 2019 |
| Alisa International Limited | Wholesale & retail | 2022 |
| ALL Go Motorhome Sales & Hire Limited | Wholesale & retail | 2025 |
| ALL Journey Solutions Ltd | Transport & logistics | 2026 |
| ALL Vision Limited | Manufacturing | 2019 |
| Allin Property Developments Ltd | Real estate | 2024 |
| Allure Accessories Ltd | Wholesale & retail | 2025 |
| ALM White Gables Ltd. | Manufacturing | 2017 |
| Aloe Environmental Consulting Ltd | Professional & scientific | 2025 |
| Aloe Vera 1 Limited | Hospitality | 2025 |
| Alpha Business Supplies Limited | Wholesale & retail | 2019 |
| Alpha Health Partners Limited | Professional & scientific | 2025 |
| Alps Holdings Limited | Professional & scientific | 2015 |
| Altass-Cheshire Limited | Extraterritorial | 2016 |
| Altbit Limited | Information & communication | 2015 |
| AM Thomas Property Ltd | Real estate | 2019 |
| Amberage Limited | Real estate | 2017 |
| Ambergate House Limited | Real estate | 2014 |
| AMC Properties Yorkshire Ltd | Real estate | 2026 |
| Ameliah Properties Ltd | Real estate | 2023 |
| AMF Housing Ltd | Real estate | 2018 |
| Amflo Care Services Ltd | Health & social care | 2018 |
| Amlyn Ltd | Wholesale & retail | 2024 |
| Amnk Consult Ltd | Professional & scientific | 2022 |
| Amsam Properties Limited | Real estate | 2023 |
| Amvb Properties Ltd | Real estate | 2023 |
| Anbev Alliance Limited | Financial services | 2023 |
| Anchor Enterprise Group Ltd | Financial services | 2021 |
| Ancora Law Ltd | Professional & scientific | 2019 |
| Andrew Brooks Recovery Ltd | Wholesale & retail | 2020 |
| Andrew Chandler Ltd | Professional & scientific | 2004 |
| Andrew Waide Associates Ltd | Professional & scientific | 2008 |
| Andrews Motor Engineers Ltd | Wholesale & retail | 2019 |
| Anfo Contracting & Consulting Limited | Professional & scientific | 2017 |
| Anne Bedford Limited | Agriculture & fishing | 2003 |
| Anota Limited | Information & communication | 2011 |
| Anveshan Ventures Limited | Financial services | 2025 |
| Anyi Consulting Ltd | Professional & scientific | 2024 |
| Apdmd Ltd | Financial services | 2019 |
| Apollo Office Supplies Limited | Wholesale & retail | 2000 |
| Appletree House Residential Care Home Limited | Health & social care | 2006 |
| Applied Label Solutions Ltd | Manufacturing | 2002 |
| Approved Heating Systems Limited | Construction | 2007 |
| Appscert Ltd | Professional & scientific | 2016 |
| APS Yorkshire Ltd | Real estate | 2023 |
| AQA Power Solutions Ltd | Administrative & support | 2026 |
| Aquaelite Plumbing & Heating Limited | Construction | 2021 |
| Aquatics Solutions Ltd | Wholesale & retail | 2023 |
| Aquaxplore Limited | Transport & logistics | 2004 |
| ARC Fitness & Wellbeing Ltd | Arts & recreation | 2025 |
| Archetype Medtech Ltd | Professional & scientific | 2023 |
| Archimedes Ventures Limited | Real estate | 2014 |
| Archplan Limited | Manufacturing | 2012 |
| Ardan Training Consultancy Limited | Education | 2006 |
| Ardent Design Limited | Construction | 2023 |
| Ardere Limited | Wholesale & retail | 2016 |
| Aria Software Ltd | Information & communication | 2026 |
| ARK Kitchens and Joinery Limited | Manufacturing | 2010 |
| Armao Ltd | Real estate | 2020 |
| Armstrong Massey (Driffield) Limited | Extraterritorial | 2015 |
| Armstrong Massey (Investments) Limited | Real estate | 2015 |
| Armstrong Massey (Property) Limited | Real estate | 2015 |
| Arramel UK Ltd | Administrative & support | 2009 |
| Arrowsmith Analytics Group Ltd | Information & communication | 2024 |
| Artemis Nearshore Marine Consultants Ltd | Professional & scientific | 2023 |
| Arun Signs Limited | Manufacturing | 2011 |
| Ashleigh (Holdings) Limited | Professional & scientific | 2003 |
| Ashton Assessors Limited | Health & social care | 2015 |
| Ashton Roofing Contractors Limited | Construction | 1990 |
| Ashwood Gardens (Driffield) Management Company Limited | Households | 2004 |
| Aspen Creative Resources Limited | Professional & scientific | 1997 |