| Aais Solutions Ltd | Construction | 2016 |
| AAK Plumbing and Heating Ltd | Construction | 2022 |
| Aaron NOT Alan Productions Ltd | Information & communication | 2013 |
| Abbey Court Management (Owners) Limited | Real estate | 2002 |
| Abbey Court Property Management Company (Rhuddlan) Limited | Households | 2007 |
| Abbey Vale Management Company Limited | Households | 2024 |
| Abbotts Walk Management Company Limited | Households | 2012 |
| ABC Business Brokers Limited | Extraterritorial | 2008 |
| Abella Investment Limited | Real estate | 2014 |
| Above Target Hire Ltd | Water & waste | 2019 |
| Abrahams Court (Upminster) Management Co. Limited | Households | 1999 |
| Absolute Technical Services Limited | Construction | 2010 |
| Abundant Care Solutions Ltd | Administrative & support | 2022 |
| Accelerated Medical Solutions Ltd | Professional & scientific | 2024 |
| Ace Cars of Hertfordshire Ltd | Transport & logistics | 2013 |
| Ace Logistics Ltd | Transport & logistics | 2018 |
| Acidy Ltd. | Information & communication | 1999 |
| ACT3 Consulting Limited | Professional & scientific | 2021 |
| Adamson Facades Ltd | Construction | 2019 |
| Adaptit Computer Services Ltd | Information & communication | 2014 |
| Adaptit Construction Limited | Construction | 2016 |
| Adaptor Clothing Limited | Wholesale & retail | 2012 |
| ADC Bioscientific Limited | Manufacturing | 1997 |
| ADC Hoddesdon Ltd | Wholesale & retail | 2023 |
| Addison Estates Limited | Real estate | 1969 |
| Adegbola HC Ltd | Health & social care | 2018 |
| Adib Services Ltd | Transport & logistics | 2016 |
| Admart Europe Limited | Professional & scientific | 2025 |
| Adonai Holdings Limited | Financial services | 2005 |
| Adonai Lettings Limited | Hospitality | 2018 |
| Adriatic Limited | Real estate | 2001 |
| ADT Electrical Services Ltd | Construction | 2026 |
| Advanced Glass Technology (International) Limited | Manufacturing | 2017 |
| Advanced Information Access (London) Limited | Information & communication | 2018 |
| Advanced Web Designs Limited | Information & communication | 2000 |
| Advantage Technical Services Ltd | Construction | 2004 |
| Adventure Buddies Respite Ltd | Health & social care | 2026 |
| Adventz Limited | Wholesale & retail | 2020 |
| AE & Llakaj Investment Ltd | Real estate | 2020 |
| AER Training Limited | Professional & scientific | 2011 |
| Aesthetics E.M.S. Limited | Health & social care | 2024 |
| AF Consultancy (London) Limited | Professional & scientific | 2014 |
| Affinity Recruitment Limited | Administrative & support | 2026 |
| Africa Power and Electric Company Limited | Professional & scientific | 2018 |
| Agecroft Estates Management Company Limited | Households | 2003 |
| AHM Homes Ltd | Real estate | 2025 |
| Aiver Contracts Limited | Arts & recreation | 1985 |
| AJ Aura Properties Ltd | Real estate | 2026 |
| AJ Media Associates Ltd | Manufacturing | 2010 |
| AJC Finance Ltd | Financial services | 2022 |
| AJR Windows Ltd | Construction | 2016 |
| Akron Gate Holdings Ltd | Real estate | 2016 |
| AKS Media Ltd | Information & communication | 1998 |
| Alao Clothing Limited | Wholesale & retail | 2025 |
| Albany Flat Management Company Limited | Households | 2001 |
| Albany Shipbrokers Limited | Administrative & support | 1982 |
| Albarom Ltd | Wholesale & retail | 2011 |
| Albert Mews (Ramsgate) Management Limited | Households | 2006 |
| Albion (Merton) Management Company Limited | Households | 1986 |
| Aldenham Road (Bushey) Management Company Limited | Households | 2013 |
| Alderbrook Manor Residential Management Company Limited | Households | 2026 |
| Alderstone Park and Oakview Quarter (Great Eccleston) Management Company Limited | Households | 2025 |
| Aleph Insights Limited | Professional & scientific | 2014 |
| Alex Homes Ltd | Households | 2021 |
| Alexander JON Compliance Consulting Limited | Professional & scientific | 2019 |
| Alexandra Court (Chorlton) Residents Association Limited | Households | 2004 |
| Alexandra Court (Hatfield) Management Company Limited | Households | 2004 |
| Alexandra Gardens (Hull) Management Company Limited | Households | 2017 |
| Alexandra House Management Company Limited | Households | 1979 |
| Alexandra Wharf Docks Management Company Limited | Households | 2026 |
| Alexia Hargrave Limited | Professional & scientific | 2026 |
| ALI Legacy Capital Ltd | Financial services | 2017 |
| Alias Advisory Ltd | Professional & scientific | 2019 |
| Alibaba SYD Limited | Professional & scientific | 2025 |
| Alicya Limited | Wholesale & retail | 2018 |
| Alimos Limited | Wholesale & retail | 2008 |
| Alize Marine Holdings Ltd | Financial services | 2016 |
| Alkemy Partners Ltd | Information & communication | 2020 |
| ALL About Images Ltd | Professional & scientific | 2025 |
| ALL About Today Ltd | Information & communication | 2024 |
| ALL Cool Ltd | Professional & scientific | 2021 |
| ALL GAS Services (London) Limited | Construction | 2007 |
| ALL the Floors Ltd | Construction | 2015 |
| ALL4HOUSE London Ltd | Construction | 2014 |
| Allan Reece & Co Limited | Professional & scientific | 2001 |
| Allbrook View Management Limited | Households | 2013 |
| Allen Harding Promotions Limited | Manufacturing | 1996 |
| Allendale Group Ltd | Manufacturing | 2003 |
| Allerton Place Management Company Limited | Households | 2016 |
| Allied People Group Limited | Financial services | 2021 |
| Allway Logistics Limited | Transport & logistics | 2024 |
| Allwood Automobile Company Limited | Wholesale & retail | 2010 |
| Almond Court Management (Southampton) Limited | Households | 1985 |
| Alpha Capital Partnership Ltd | Other services | 2022 |
| Alranor Properties Limited | Real estate | 2020 |
| Alsa Building Services Ltd | Construction | 2021 |
| Alternative Salon Ltd | Other services | 2011 |
| Altrapoint Ltd | Extraterritorial | 2026 |
| Alverley Mews (Doncaster) Management Company Limited | Households | 2026 |
| Amakk Ltd | Hospitality | 2017 |