| ADK Motors Ltd | Wholesale & retail | 2025 |
| Adkins Consultants Limited | Construction | 2011 |
| Adkins Consulting Ltd | Construction | 2024 |
| ADM Construction Services Limited | Professional & scientific | 2016 |
| ADM Improvements Ltd | Construction | 2025 |
| Admaria Limited | Professional & scientific | 2024 |
| Admiral's ARM Hospitality Ltd | Hospitality | 2026 |
| ADN Homes Ltd | Real estate | 2025 |
| Adolphus Properties Ltd | Real estate | 2016 |
| Adom Smart Buildings Ltd | Construction | 2020 |
| Adplan Creative Limited | Professional & scientific | 2018 |
| Adriankaloyanbrothers Ltd | Transport & logistics | 2021 |
| Adsig Holdings Ltd | Manufacturing | 2017 |
| Adsig Ltd | Manufacturing | 2022 |
| Adsn Solutions Limited | Wholesale & retail | 2005 |
| Adusky Comfort Living Limited | Health & social care | 2023 |
| Advance Drylining Distribution Limited | Transport & logistics | 2009 |
| Advance Facilities Group Ltd | Administrative & support | 2018 |
| Advance Facilities Solutions Ltd | Administrative & support | 2012 |
| Advance Technical Solutions T/A Advance Ltd | Administrative & support | 2018 |
| Advanced Business Coaching Limited | Administrative & support | 2022 |
| Advanced Camera Services Limited | Other services | 2024 |
| Advanced Digital Media Solutions Limited | Professional & scientific | 2012 |
| Advanced DRY Risers Ltd | Public administration | 2025 |
| Advanced Fractions Ltd | Information & communication | 2024 |
| Advanced Spectrum Limited | Professional & scientific | 2008 |
| Advanced Tooling Systems (Group) Ltd | Financial services | 2018 |
| Advanced Tooling Systems (Holdings) Ltd | Professional & scientific | 2012 |
| Advanced Tooling Systems UK Limited | Manufacturing | 2002 |
| Advanced Trench-Less Technologies Ltd | Water & waste | 2018 |
| Advancedsashwindows Limited | Manufacturing | 2018 |
| Advantage Mediation Ltd | Professional & scientific | 2018 |
| Advent Homes Limited | Hospitality | 2023 |
| Adventure Learning Academy Trust | Education | 2013 |
| Adventure Yachting LLP | | 2023 |
| Advertising Excellence Limited | Professional & scientific | 1998 |
| Advo Holdings Limited | Professional & scientific | 2005 |
| Advo Limited | Administrative & support | 2001 |
| Advo One Limited | Administrative & support | 2001 |
| Ady&George Ltd | Administrative & support | 2024 |
| AE Simplicity Limited | Administrative & support | 2016 |
| Aegeus Capital Limited | Financial services | 2016 |
| Aenea Programme Ltd | Information & communication | 2014 |
| Aequus Investment Holdings Ltd | Financial services | 2020 |
| Aequus Investment Ltd | Health & social care | 2017 |
| Aeris Projects Ltd | Construction | 2013 |
| Aero Legends Fixed Based Operations Limited | Other services | 2018 |
| Aero Legends Leasing Limited | Other services | 2018 |
| Aero Legends Limited | Arts & recreation | 2011 |
| Aero Optical Limited | Professional & scientific | 2005 |
| Aerosignal Consulting Ltd | Professional & scientific | 2025 |
| Aerovolve Engineering Ltd | Manufacturing | 2024 |
| Aesteelsolutions Ltd | Construction | 2023 |
| Aesthetech Limited | Health & social care | 2021 |
| Aesthetic Edge-Dental Ltd | Health & social care | 2022 |
| Aevisa Holdings Ltd | Financial services | 2026 |
| Aevum Ventures Limited | Professional & scientific | 2022 |
| AF Consultants Ltd | Professional & scientific | 2020 |
| AFA Recovery Ltd | Transport & logistics | 2026 |
| AFC Property Solutions Ltd | Construction | 2025 |
| Affable Piling Co. Ltd | Construction | 2004 |
| Affiliate Contractors Limited | Construction | 2018 |
| Afforda Ltd | Professional & scientific | 2013 |
| Affordable Automotive Services Ltd | Wholesale & retail | 2018 |
| Afiaafrica Ltd | Wholesale & retail | 2024 |
| Aford Awards Limited | Wholesale & retail | 2005 |
| African Foods Ltd | Wholesale & retail | 2022 |
| Afro Caribbean Designs Ltd. | Health & social care | 2014 |
| AFS Medical Limited | Health & social care | 2020 |
| AG Baltimore Limited | Real estate | 2017 |
| AG Driveways Ltd | Construction | 2014 |
| AG Fire Consultancy Limited | Professional & scientific | 2022 |
| AG Group (Kent) Limited | Construction | 2024 |
| AG Market Data Services Ltd | Information & communication | 2013 |
| AG Osteopathy & Sports Clinic Ltd | Health & social care | 2025 |
| AGA Tech Limited | Professional & scientific | 2009 |
| Agalina International Ltd | Information & communication | 2023 |
| Agati Ltd | Transport & logistics | 2022 |
| AGE UK Maidstone Sevenoaks & Tonbridge | Health & social care | 1997 |
| Agenda Consulting Limited | Professional & scientific | 2002 |
| Agentics MAS Limited | Information & communication | 2025 |
| Aghabridge (2020) Holdings Limited | Financial services | 2020 |
| Aghabridge Group Account Limited | Financial services | 2014 |
| Aghabridge Limited | Wholesale & retail | 1978 |
| Agile Consulting Group Ltd | Professional & scientific | 2022 |
| Agistri Ltd | Transport & logistics | 2018 |
| Agri Parts and Accessories Limited | Wholesale & retail | 2015 |
| Agrip Limited | Transport & logistics | 2016 |
| Agrp Limited | Health & social care | 2026 |
| AGS Plumbing & Heating Services Ltd | Construction | 2021 |
| Agve Limited | Manufacturing | 2015 |
| Ahad & Tufayl Consulting Limited | Hospitality | 2013 |
| Ahar Transport Ltd | Transport & logistics | 2022 |
| Ahiafoods Ltd | Hospitality | 2022 |
| AHL Engineering Ltd | Wholesale & retail | 2013 |
| Ahmaka Afrik Ltd | Manufacturing | 2025 |
| Ahmed Adam Medical Limited | Health & social care | 2023 |
| AI Proptec Ltd | Information & communication | 2025 |
| Aice Technology Limited | Information & communication | 2025 |
| AIM Focus Media Ltd | Information & communication | 2019 |