| AB and MT Limited | Other services | 2016 |
| AB Procurement Ltd | Other services | 2015 |
| Abacus Agriculture Limited | Agriculture & fishing | 2014 |
| Abacus Cycles Holdings Ltd | Wholesale & retail | 2026 |
| Abacus Cycles Limited | Wholesale & retail | 2024 |
| Abacus Organic Associates Limited | Professional & scientific | 2012 |
| Abbey Professional Services Ltd | Information & communication | 2026 |
| Abbot's Hospital Trustee Company | Hospitality | 2006 |
| Abbotswood Consulting Ltd | Professional & scientific | 2011 |
| Abbotswood Residents Association Limited | Households | 1983 |
| ABC Television Ltd | Information & communication | 2014 |
| Aber Consultancy Services Ltd | Professional & scientific | 2020 |
| Abinger Marquee Hire Limited | Administrative & support | 2001 |
| Abis and Abishi Ltd | Wholesale & retail | 2020 |
| Able Medical Ltd | Health & social care | 2020 |
| Ableway Associates Limited | Wholesale & retail | 2008 |
| Ableway Investments Limited | Real estate | 2017 |
| Abnix Solutions Limited | Information & communication | 2006 |
| Abode Escapes Ltd | Real estate | 2021 |
| About Sports UK Limited | Arts & recreation | 2011 |
| Abricot Production Ltd | Administrative & support | 2017 |
| Absolute Learning Ltd | Education | 2009 |
| Absolute Return Capital Management Ltd | Administrative & support | 2008 |
| Absolutely Flawless Beauty Ltd | Other services | 2024 |
| Absolutely Games Limited | Information & communication | 2019 |
| Absolutely Mars Limited | Information & communication | 2020 |
| Abstract Music Productions Limited | Information & communication | 2002 |
| ABT Couriers Ltd | Transport & logistics | 2016 |
| Academy of British Nesol Ltd | Education | 2018 |
| Acal Electronics Limited | Professional & scientific | 1985 |
| Acasta Consulting Limited | Administrative & support | 2008 |
| Accelerate Iberia Esports Holdings Ltd | Financial services | 2026 |
| Accelogress Limited | Information & communication | 2012 |
| Accountancypro Limited | Financial services | 2023 |
| Accountax International Limited | Professional & scientific | 2018 |
| Accounting Services FA Limited | Other services | 2012 |
| Accountsource Limited | Professional & scientific | 2004 |
| Accretive Evolution Ltd | Professional & scientific | 2018 |
| Accucoms International Ltd | Wholesale & retail | 2020 |
| Ace Bicycles Ltd | Manufacturing | 2016 |
| Ace Copyrights Limited | Information & communication | 2016 |
| Ace Fundraising Ltd | Administrative & support | 2023 |
| Ace Heating and Plumbing Ltd | Construction | 2012 |
| Ace Software Development Ltd | Information & communication | 2023 |
| Acer Tennis Lettings Limited | Real estate | 2004 |
| Achrn Ltd | Professional & scientific | 2011 |
| ACI UK Learning Limited | Administrative & support | 2006 |
| ACM Creative Ltd | Professional & scientific | 2019 |
| ACM Guildford Limited | Education | 2018 |
| Acma Trading Ltd | Professional & scientific | 2025 |
| Acms Property Services Limited | Real estate | 2024 |
| Acof Ltd | Information & communication | 2021 |
| Acoustic Sensor Networks Limited | Professional & scientific | 2016 |
| Acre 869 Limited | Real estate | 2004 |
| Acre Consulting Limited | Administrative & support | 2026 |
| Acrossword Limited | Information & communication | 2026 |
| Actec Electrical Consulting Ltd | Professional & scientific | 2015 |
| Actech Holdings Limited | Professional & scientific | 1995 |
| Actica Commercial Property Ltd | Real estate | 2017 |
| Actica Consulting Limited | Information & communication | 1997 |
| Actica Holdings Limited | Information & communication | 2009 |
| ACTIV8 Energies UK Limited | Other services | 2024 |
| Active Oaps Cleaning Services Ltd | Administrative & support | 2018 |
| Activlearning Limited | Arts & recreation | 2024 |
| Activmethod Ltd | Arts & recreation | 2026 |
| Acton Storage Solutions Ltd | Transport & logistics | 2016 |
| Actsouth Property Management Limited | Households | 1984 |
| Actualize Consulting Group Ltd | Information & communication | 2023 |
| Actureon Ltd | Information & communication | 2025 |
| Acuity Training Limited | Education | 2011 |
| AD Car Care Wimbledon Limited | Wholesale & retail | 2018 |
| AD Holdco 1 Limited | Financial services | 2024 |
| AD Menswear Ltd | Wholesale & retail | 2025 |
| AD Repairs Ltd | Other services | 2012 |
| AD3K Limited | Other services | 2026 |
| Adam O'Neill Restaurant Group Ltd | Hospitality | 2025 |
| Adamas Consulting Group Limited | Professional & scientific | 2012 |
| Adamas Consulting Limited | Professional & scientific | 1997 |
| Addibuddy Ltd | Information & communication | 2023 |
| Addies Distribution Ltd | Wholesale & retail | 2026 |
| Addimus Limited | Administrative & support | 2012 |
| Addison Glass & Windscreens Ltd | Construction | 1975 |
| Addison Hayes Limited | Professional & scientific | 2017 |
| Adelaide Estates Limited | Real estate | 2016 |
| Adeptiq Consulting Ltd | Professional & scientific | 2014 |
| Adhd Care Ltd | Health & social care | 2018 |
| Adjutant MTC Limited | Professional & scientific | 2002 |
| ADL Motors Limited | Wholesale & retail | 2013 |
| Adleo Ltd | Administrative & support | 2024 |
| Adlowe Ltd | Information & communication | 2020 |
| Admains Technology Limited | Information & communication | 2016 |
| Admistaff Limited | Administrative & support | 2025 |
| Adnan Kebab 1 Ltd | Hospitality | 2024 |
| Adrian Gibson Music Productions Limited | Arts & recreation | 2008 |
| Adrian Sutton Limited | Other services | 2020 |
| ADS Collective Limited | Professional & scientific | 2025 |
| Adsimulo Ltd | Information & communication | 2016 |
| Adults Play Limited | Wholesale & retail | 2022 |
| Advance TRS Ltd. | Professional & scientific | 2011 |
| Advanced Aviation Technology Limited | Professional & scientific | 1997 |