| ACM Property Holdings Limited | Real estate | 2019 |
| Acord Cars Ltd | Administrative & support | 2017 |
| Acquah Property Ltd | Real estate | 2024 |
| ACR Capital Consultants Limited | Professional & scientific | 2014 |
| ACR Goods Ltd | Wholesale & retail | 2026 |
| Acrgroundworks Ltd | Construction | 2024 |
| Across Pilgrimages & Travel | Professional & scientific | 2019 |
| ACT Three Ltd | Professional & scientific | 2010 |
| Actability Ltd | Arts & recreation | 2005 |
| Actisell Limited | Professional & scientific | 2014 |
| Adam Curtis Limited | Hospitality | 2012 |
| Adams & Cullen Investments Ltd | Real estate | 2025 |
| Adanna Ventures Limited | Real estate | 2026 |
| Adansi Healthcare Ltd | Health & social care | 2011 |
| Adapt and Construct Limited | Construction | 2012 |
| Adele Fensham Consulting Limited | Information & communication | 2023 |
| Adept Property Consultants Limited | Professional & scientific | 2017 |
| Adeptus Victoria Limited | Education | 2025 |
| Adetoro Ltd | Health & social care | 2025 |
| Adil & Sons Ltd | Real estate | 2025 |
| ADR Business Ltd | Construction | 2025 |
| Adtl Limited | Households | 2018 |
| Adunni Estate Ltd | Real estate | 2025 |
| Adventure Island Playbarn Ltd | Arts & recreation | 2010 |
| Advertising LAB Ltd | Professional & scientific | 2017 |
| Advisory Nexus Ltd | Information & communication | 2024 |
| AEA Express Ltd | Transport & logistics | 2016 |
| Aecer Associates Limited | Real estate | 2009 |
| Aegis Data Consulting Ltd | Administrative & support | 2025 |
| Aegis Data Protection Consulting Limited | Public administration | 2025 |
| Aero Solutions Group UK Limited | Financial services | 2025 |
| Aesthetically Pleasing Home Ltd | Wholesale & retail | 2022 |
| Affinnity Limited | Professional & scientific | 2011 |
| Affordable Car Rental Limited | Real estate | 2002 |
| Affordable Car Storage Ltd | Transport & logistics | 2023 |
| Afonso Coffee House Ltd | Hospitality | 2023 |
| AG & AJ Akhurst Limited | Administrative & support | 2020 |
| AGB Building & Roofing Ltd. | Construction | 2019 |
| AGI Infinity Limited | Information & communication | 2024 |
| Agile Contracting Ltd | Information & communication | 2010 |
| Agitprop Ltd | Manufacturing | 2011 |
| AGM - a Growth Mindset Ltd | Professional & scientific | 2024 |
| Agnichem Limited | Professional & scientific | 2003 |
| AHE123 Limited | Professional & scientific | 1985 |
| Ailyne Ltd | Information & communication | 2023 |
| Aime Holdings Ltd | Construction | 2023 |
| Aimia Advisory Limited | Administrative & support | 2020 |
| Air-Con on Demand Ltd | Construction | 2025 |
| Airframer Ltd | Administrative & support | 2016 |
| Airport Rentacar Ltd | Administrative & support | 2025 |
| Airport Rentacar Southend Ltd | Administrative & support | 2025 |
| AJ Landscapes & Property Maintenance Ltd | Administrative & support | 2020 |
| AJ Lane (Holdings) Limited | Financial services | 2021 |
| Ajcraft Ltd | Construction | 2025 |
| AJD Landscapes Ltd | Administrative & support | 2018 |
| AJG Therapies Ltd | Health & social care | 2021 |
| AJH Systems Limited | Professional & scientific | 2021 |
| AJL Scaffolding Limited | Construction | 2017 |
| AK Path Ltd | Health & social care | 2018 |
| Akasha Wellness Limited | Arts & recreation | 2014 |
| Akker Properties Ltd | Construction | 2011 |
| AKN Engineering Limited | Professional & scientific | 2019 |
| AKN Surveys Ltd | Professional & scientific | 2023 |
| Alan Ginger IT Services Limited | Information & communication | 2014 |
| Albany 21 Ltd | Professional & scientific | 2015 |
| Albion Design Limited | Manufacturing | 2012 |
| Albion Hemp Ltd | Agriculture & fishing | 2019 |
| Albury Place Management Company Limited | Real estate | 2019 |
| Alchemy Analytics Limited | Information & communication | 2017 |
| Aldridge Glass Limited | Manufacturing | 2013 |
| Alefid Limited | Wholesale & retail | 2023 |
| Aleon Property Ltd | Real estate | 2024 |
| Alessandro DI LEO Pasticceria Ltd | Wholesale & retail | 2020 |
| Alex 79 Ltd | Wholesale & retail | 2025 |
| Alex Car Repair Ltd | Wholesale & retail | 2017 |
| Alex Merry Consultancy Limited | Professional & scientific | 2013 |
| Alexander Court (Cheshunt) Management Company Limited | Households | 1990 |
| Alexandra Didio Ltd | Professional & scientific | 2024 |
| Alexandrew Ltd | Wholesale & retail | 2023 |
| Aley Design Consultancy Ltd | Professional & scientific | 2021 |
| Algo Positive Ltd | Wholesale & retail | 2024 |
| Alice Hollis Ltd | Information & communication | 2019 |
| Alice Molloy Interiors Limited | Construction | 2018 |
| Alijam Ltd | Information & communication | 2017 |
| Aliveko Mortgages & Protection Ltd | Financial services | 2023 |
| Alkemista Limited | Manufacturing | 2018 |
| Alkemista Partners LLP | | 2022 |
| Alken Investment Company Limited | Real estate | 1964 |
| ALL BMS Systems Limited | Construction | 2009 |
| ALL Counties Electrical Services Limited | Construction | 2016 |
| ALL County Group Ltd | Administrative & support | 2019 |
| ALL County Landscaping Ltd | Administrative & support | 2021 |
| ALL Klasse Autos Limited | Wholesale & retail | 2012 |
| Alleada Associate Ltd | Wholesale & retail | 2025 |
| Allerton Bishop Limited | Administrative & support | 2025 |
| Allgood Systems Limited | Real estate | 2001 |
| Alliance Consulting Engineers Ltd | Professional & scientific | 2025 |
| Allium Design & Print Services Limited | Administrative & support | 2016 |
| Allium Wood Limited | Professional & scientific | 2009 |
| Alloncourse Limited | Education | 2021 |