| Alchemist Retreats Limited | Hospitality | 2023 |
| Alchemy Parts Limited | Wholesale & retail | 2012 |
| Aldridge Road Villas Freehold Limited | Households | 2012 |
| Alegra Asset Limited | Administrative & support | 2006 |
| Aleph Invest Ltd | Administrative & support | 2015 |
| Alexander Beck Ltd | Construction | 2020 |
| Alexpharm GmbH Ltd | Wholesale & retail | 2007 |
| Alfa Cleaning 11 Ltd | Administrative & support | 2021 |
| Alfa Construction 11 Ltd | Construction | 2021 |
| Algebrains Capital Ltd | Education | 2016 |
| Algo Art Limited | Other services | 2018 |
| Alice Elsie DAN Limited | Real estate | 2021 |
| Alida London Limited | Manufacturing | 2024 |
| Align Health Limited | Health & social care | 2019 |
| Alike Solutions Limited | Professional & scientific | 2010 |
| Alim Properties Ltd | Administrative & support | 2012 |
| ALL Food Packaging UK Limited | Financial services | 2015 |
| ALL GAS Heating Ltd | Construction | 2017 |
| ALL Grades Direct Glazing Ltd | Construction | 2026 |
| ALL in One Building and Property Services Ltd | Administrative & support | 2015 |
| ALL in One Contractors Ltd | Construction | 2017 |
| ALL Nation Surveying Services Ltd | Construction | 2020 |
| ALL Pawz on Deck Ltd | Other services | 2018 |
| Allander Warehouse Company (Sports & Leisure) Limited | Professional & scientific | 1989 |
| Allander Warehouse Company Limited | Professional & scientific | 2011 |
| Allcare Solutions Limited | Wholesale & retail | 2024 |
| Allond Limited | Professional & scientific | 2016 |
| Allprop Contracts Limited | Professional & scientific | 2025 |
| Allprop Property Maintenance Limited | Administrative & support | 2013 |
| Allseal Glass Limited | Construction | 2012 |
| Allseal Glazing Ltd | Construction | 2023 |
| Allseasons Boarding Cattery Ltd | Hospitality | 2014 |
| Allways Supply CC Ltd | Wholesale & retail | 2025 |
| Allwright (London) Limited | Professional & scientific | 1951 |
| Alma Court Residents Limited | Households | 1996 |
| ALP Cuce Investments Ltd | Real estate | 2021 |
| ALP Homes London Ltd | Real estate | 2024 |
| Alpha Bears Day Care Nursery Ltd | Health & social care | 2015 |
| Alpha Butchers Ltd | Wholesale & retail | 2024 |
| Alpha Cooling Professional UK Ltd | Administrative & support | 2019 |
| Alpha Numbers Ltd | Information & communication | 2022 |
| Alpha Project Constructions Limited | Construction | 2018 |
| Alpha-B Cleaning Ltd | Administrative & support | 2024 |
| Alpha-B Group Ltd | Other services | 2014 |
| Alst LLP | | 2015 |
| Altea Homes Limited | Real estate | 2020 |
| Altered Aspect VFX Limited | Information & communication | 2020 |
| Alternative Hair International Ltd | Other services | 2016 |
| Alternative Pathways Ltd | Education | 2024 |
| Alternative Property Ltd | Real estate | 2018 |
| Althaia Ltd | Wholesale & retail | 2020 |
| Always Positive Limited | Information & communication | 2019 |
| Alwilo Limited | Professional & scientific | 2014 |
| Amanda Properties (UK) Ltd | Real estate | 2018 |
| Amario Autos Ltd | Wholesale & retail | 2023 |
| Amber Gold Group Ltd | Real estate | 2026 |
| Amber Hair & Beauty Ltd | Other services | 2022 |
| Amber Sound Limited | Wholesale & retail | 2005 |
| AMC Financial Solutions Limited | Professional & scientific | 2017 |
| Amdh Smile Limited | Health & social care | 2024 |
| Amed Consultancy Ltd | Professional & scientific | 2025 |
| American Tax Consulting UK Ltd | Professional & scientific | 2021 |
| Americo 2022 Limited | Real estate | 2022 |
| Americo Limited | Construction | 2017 |
| Ameris Intelligence Limited | Information & communication | 2021 |
| Ameris Limited | Information & communication | 2002 |
| Amethyst Osteopathic Clinic Limited | Health & social care | 2007 |
| Amici Venezia Ltd | Hospitality | 2025 |
| Amil Investments Ltd | Real estate | 2020 |
| Amondin Limited | Financial services | 2022 |
| AMP One Studios Ltd | Information & communication | 2023 |
| Amplifico Learning Limited | Administrative & support | 2024 |
| Ampro Electrical Ltd | Construction | 2019 |
| AMS Leisure Supplies Limited | Administrative & support | 2003 |
| Amwell House Management Company Limited | Real estate | 2018 |
| AMY Warnock Limited | Information & communication | 2018 |
| AN Group Services Limited | Construction | 2020 |
| Anacris Trans Ltd | Transport & logistics | 2019 |
| Anaiyashah & Co Limited | Real estate | 2023 |
| Analogue Design Ltd | Professional & scientific | 2022 |
| Anastasi (2010) Limited | Administrative & support | 2010 |
| Anastasi Estates Limited | Real estate | 2005 |
| Anastasi London Limited | Real estate | 2009 |
| Anastasi Property Group Limited | Real estate | 2025 |
| Andal Services Ltd | Financial services | 2014 |
| Andana Foods Limited | Hospitality | 2009 |
| Andersons Group Limited | Real estate | 2026 |
| Andras & SON Ltd | Transport & logistics | 2015 |
| Andrew Clark Rail Consultancy Limited | Professional & scientific | 2014 |
| Andreya Triana Touring Limited | Information & communication | 2018 |
| Androdame Ltd | Administrative & support | 2014 |
| Andronika Limited | Real estate | 2012 |
| Andwell & Co Ltd | Real estate | 2024 |
| Andy Bays Creative Ltd | Hospitality | 2020 |
| ANG Cars Limited | Administrative & support | 2015 |
| Angel Electrical Contractors Limited | Construction | 1971 |
| Angel Star Ltd | Information & communication | 2026 |
| Angelos Professional Tiles Ltd | Construction | 2020 |
| Angh Group Ltd | Administrative & support | 2018 |
| Anglo Italian Academy of Art Limited | Professional & scientific | 2001 |