| Acre Bedmond Ltd | Real estate | 2025 |
| Acre Crews Hill Ltd | Real estate | 2025 |
| Acre North Weald Ltd | Real estate | 2025 |
| Acre Slough 2 Ltd | Real estate | 2025 |
| Acre South Heath Ltd | Real estate | 2025 |
| Acre Sundon Ltd | Real estate | 2021 |
| Acre Welham Green Ltd | Real estate | 2021 |
| Acre Welham Manor Limited | Real estate | 2022 |
| Actaris Group Limited | Real estate | 2025 |
| Active Electrical Installations Ltd | Construction | 2004 |
| Actuarius Risk & Value Management Limited | Professional & scientific | 2008 |
| Acute Developments (Chingford) Limited | Professional & scientific | 2006 |
| Adducent Ltd | Information & communication | 2004 |
| Adelaide Gardens (Residents) Management Company Limited | Households | 2026 |
| Adelaide UK Limited | Professional & scientific | 1995 |
| Adrian Carlan Limited | Construction | 2015 |
| Adrian Wallace & Co Limited | Professional & scientific | 2022 |
| ADS Global Services Limited | Other services | 2007 |
| Aesthetic Skin Clinic Totteridge Ltd | Other services | 2006 |
| AF Elite Ltd | Other services | 2024 |
| Africa Build Limited | Administrative & support | 2002 |
| AFT Elite Ltd | Other services | 2024 |
| Agile Document Solutions Limited | Information & communication | 1999 |
| AGM Housing Ltd | Real estate | 2024 |
| Agye Rock Ltd | Real estate | 2021 |
| Ahmad Vision Holdings Ltd | Professional & scientific | 2023 |
| Ainsel Limited | Manufacturing | 2014 |
| Airbus Defence and Space Limited | Manufacturing | 1989 |
| Aiza Beauty & Aesthetics Ltd | Other services | 2003 |
| AJ Prestige Customz Ltd | Professional & scientific | 2017 |
| Ajaks Developments Limited | Wholesale & retail | 2003 |
| Akeman Management Company Limited | Professional & scientific | 2003 |
| AKN Engineering Longfield Limited | Professional & scientific | 2019 |
| Akriss Limited | Administrative & support | 2005 |
| AL Dente Catering Limited | Hospitality | 2022 |
| Alabaster Box Investment Ltd | Financial services | 2020 |
| Alan Walter Limited | Professional & scientific | 2002 |
| Alban Corporate Services Limited | Administrative & support | 1996 |
| Alban Pearson Property Company Limited | Professional & scientific | 2003 |
| Alban Transport Services Limited | | 1985 |
| Aldenham Enterprises Ltd | Arts & recreation | 1982 |
| Alexander Steer Ltd | Real estate | 2024 |
| Alexis Jewels Limited | Administrative & support | 2003 |
| Alfie Chauffeurs Ltd | Other services | 2023 |
| ALI Ustun Beheer Limited | Administrative & support | 2013 |
| Alice Records Limited | Information & communication | 2002 |
| Alistair Miller Business Management Services Limited | Professional & scientific | 2006 |
| ALL Dimension Limited | Education | 2008 |
| ALL Energy Services Ltd | Construction | 1996 |
| ALL Nations Trading Limited | Hospitality | 1974 |
| ALL4KIDSUK Limited | Information & communication | 2001 |
| Allen & Couser (Motors) Limited | Wholesale & retail | 1971 |
| Allneeds Investments Ltd | Financial services | 2026 |
| Allways Systems Limited | | 1979 |
| Almagonic Ltd | Real estate | 2012 |
| Alphacube Properties Limited | Construction | 2001 |
| Alphafirst Limited | Information & communication | 2000 |
| ALS Construction Group Ltd | Construction | 2021 |
| Alswick Hall Estates Limited | Construction | 2001 |
| Alternative Hair Ltd. | Arts & recreation | 1998 |
| Altesse Limited | Wholesale & retail | 2005 |
| Altro Group Limited | Professional & scientific | 1980 |
| Altro Limited | Manufacturing | 1919 |
| Amanda Heath Talent Development Ltd | Professional & scientific | 2016 |
| Amba Design Studio Limited | Professional & scientific | 2004 |
| Ambernet Limited | Information & communication | 1994 |
| Ambiwave Limited | Information & communication | 1998 |
| Ambro Capital Limited | Financial services | 2006 |
| AMC Coachworks Ltd | Wholesale & retail | 2014 |
| Amej Future Sales Ltd | Wholesale & retail | 2024 |
| Amelaya Ltd | Real estate | 2026 |
| AMG Quality Foods Ltd | Hospitality | 2024 |
| Amiable Management Services Limited | Administrative & support | 2007 |
| Amirol Property Ltd | Real estate | 2023 |
| Amore Holdings Ltd | Financial services | 2024 |
| Amphibian, Reptile and Mammal Conservation Limited | Construction | 1996 |
| AMS Personal Trainer Ltd | Arts & recreation | 2013 |
| Amtor Pharma LP | | 2002 |
| Amtree Farm Development Limited | Hospitality | 2002 |
| Amwell Properties Limited | Real estate | 1995 |
| Andrea & Andrea Family Investment Company Limited | Professional & scientific | 2024 |
| Andrew Lashley Design Limited | Professional & scientific | 2004 |
| Andrew Maynard Cleaning Services Limited | Administrative & support | 2001 |
| Andrew Smyth & SON Limited | Construction | 2007 |
| Angel Keys Ltd | Real estate | 2024 |
| Angelica Limited | Information & communication | 1996 |
| Angeosam Ltd | Health & social care | 2012 |
| Angie Garling Limited | Health & social care | 2003 |
| Angloworld Recruitment Limited | Administrative & support | 1995 |
| Angus Dalgleish Consulting Limited | Health & social care | 1998 |
| Anker Solix Technology (UK) Ltd | Manufacturing | 2024 |
| ANS Traffic Consulting Limited | Professional & scientific | 2014 |
| Ansem Investments Limited | Wholesale & retail | 2006 |
| Anson and Howe Limited | Administrative & support | 1994 |
| Anstey Gardens Management Company Limited | Households | 2017 |
| Anthea Pharma Limited | Manufacturing | 2022 |
| Anthony Rudelhoff Design & Development Limited | Construction | 2006 |
| Antimo Limited | Information & communication | 2000 |
| Anton Northern Rentals Ltd | Real estate | 2018 |
| Anton Property Lettings Ltd | Real estate | 2026 |