| ABR Consult Ltd | Professional & scientific | 2023 |
| Absolute NDT Limited | Professional & scientific | 2020 |
| Absolute NDT Solutions Limited | Professional & scientific | 2015 |
| Absolute Survey Ltd | Professional & scientific | 2010 |
| AC Trustees Limited | Other services | 2023 |
| Acanthus Marketing Limited | Information & communication | 2020 |
| Accounts & Legal Consulting Ltd | Professional & scientific | 2026 |
| Accsys Products Limited | Manufacturing | 2019 |
| Accu Prime Accountants Limited | Other services | 2026 |
| Ace Electrical Installations Ltd | Construction | 2013 |
| Achaval Limited | Professional & scientific | 2020 |
| Achieve Contractors Ltd | Wholesale & retail | 2014 |
| Achilles Estates Holdings Limited | Financial services | 2017 |
| Achilles Estates Limited | Real estate | 2011 |
| Achintraid International Limited | Professional & scientific | 2009 |
| Acres Building Consultants Limited | Professional & scientific | 2011 |
| Actca Limited | Professional & scientific | 2022 |
| Actima Associates Limited | Professional & scientific | 2002 |
| Active Facility Solutions Limited | Administrative & support | 2009 |
| Acupuncture Reigate Ltd | Health & social care | 2020 |
| AD Heating & Plumbing (Surrey) Limited | Construction | 2019 |
| AD Leasing Surrey Ltd | Administrative & support | 2023 |
| ADD Balance Limited | Professional & scientific | 2020 |
| ADD Cleaning Services Limited | Administrative & support | 2022 |
| Adls Financial Services Limited | Professional & scientific | 2017 |
| Administration of Justice Worldwide LLP | | 2009 |
| Admiral Fire Systems Limited | Administrative & support | 2019 |
| Admiral Holdings Ltd | Financial services | 2024 |
| Admiral Security Systems Limited | Administrative & support | 1992 |
| ADS Partnership Limited | Professional & scientific | 2018 |
| Adscensio Sports Ltd | Wholesale & retail | 2025 |
| Advanced Cardio Equipment Limited | Manufacturing | 2010 |
| Advanced Maintenance Chemicals Limited | Wholesale & retail | 1999 |
| Advantage Publishing Limited | Information & communication | 2004 |
| AE Accountax Ltd | Professional & scientific | 2014 |
| Aerios Limited | Information & communication | 2023 |
| Aesthetics Innovation Ltd | Other services | 2020 |
| AF34 Insight Limited | Information & communication | 2022 |
| Affinity Pro Limited | Information & communication | 2015 |
| Affordable Leasing Limited | Administrative & support | 2022 |
| Affordable Roofing Services Limited | Construction | 2017 |
| Afiyf Limited | Professional & scientific | 2024 |
| Agape PAY Ltd | Health & social care | 2023 |
| AGB Services Ltd | Professional & scientific | 2024 |
| AGC Plumbing & Heating Ltd | Construction | 2020 |
| Ager Aviation Limited | Transport & logistics | 2020 |
| AHJ Real Estate Ltd | Real estate | 2020 |
| Ahmad Properties Ltd | Real estate | 2013 |
| AHR Media Ltd | Professional & scientific | 2016 |
| AIF Rail Limited | Professional & scientific | 2023 |
| Aification Ltd | Professional & scientific | 2025 |
| Ains Beauty Salon Limited | Other services | 2024 |
| Ainsworth Capital Limited | Information & communication | 2010 |
| Airlocal Ltd | Administrative & support | 2018 |
| Airpulse Ltd | Wholesale & retail | 2025 |
| AJ Bookkeeping Services Ltd | Professional & scientific | 2023 |
| Ajacto Limited | Real estate | 2004 |
| AJE Consulting Solutions Limited | Information & communication | 2010 |
| AJR Pubs & Bar Management Ltd | Hospitality | 2024 |
| AJW Company Solutions Ltd | Health & social care | 2013 |
| Al-Gasa Ltd | Construction | 2022 |
| Alan Brett Associates Limited | Information & communication | 2007 |
| Albany Court Management Company Limited | Households | 1981 |
| Alder TV Ltd | Information & communication | 2016 |
| Aldersyde Consulting Limited | Professional & scientific | 2018 |
| Alderton Digital Ltd | Administrative & support | 2018 |
| Aldroubi Ltd | Administrative & support | 2019 |
| Aleezeh One Limited | Financial services | 2014 |
| Aletheia International Ltd | Professional & scientific | 2024 |
| Alexandra Consulting Ltd | Professional & scientific | 2023 |
| Alexreyn Ltd | Wholesale & retail | 2024 |
| Alfa Hospitality Ltd | Wholesale & retail | 2025 |
| Algo Novo Limited | Professional & scientific | 2019 |
| ALI Baba (2017) Limited | Other services | 2017 |
| Alice Care Recruitment Limited | Health & social care | 2022 |
| Alison Ramsay Limited | Information & communication | 2007 |
| Alium Holdings Limited | Real estate | 2018 |
| Alive Solar Ltd | Manufacturing | 2025 |
| ALL Aboard Rentals Limited | Administrative & support | 2017 |
| ALL Bathroom Supplies Limited | Wholesale & retail | 2014 |
| ALL Dance Abilities Ltd | Arts & recreation | 2022 |
| Alliano LLP | | 2024 |
| Alma Media International Limited | Information & communication | 1997 |
| Alpha Decking Ltd | Construction | 2020 |
| Alpha Education Ltd | Education | 2015 |
| Alpha EV Solutions (UK) Ltd | Professional & scientific | 2023 |
| Alpha Windows Limited | | 1991 |
| Altus Accounting and Bookkeeping Limited | Financial services | 2025 |
| AMB Assets Limited | Real estate | 2017 |
| AMB Engineering (South East) Limited | Professional & scientific | 2015 |
| Amber Associates HR Limited | Professional & scientific | 2019 |
| Amberleigh (Carlton Road) Management Limited | Households | 2008 |
| Ampersand Creative Limited | Information & communication | 2010 |
| Amusement Ride Manufacturers Limited | Arts & recreation | 2009 |
| Anderson Lewis Limited | Professional & scientific | 2013 |
| Anderton House Ltd | Financial services | 2023 |
| Andrew Bridge Lighting Design Limited | Arts & recreation | 1994 |
| Andrew Lyon Limited | Other services | 2017 |
| Andy Cross Consulting Ltd | Professional & scientific | 2016 |
| Andy Mellington Plastic Surgery Ltd | Health & social care | 2017 |