| 1 Eight 4 Limited | Information & communication | 2013 |
| 1-7 Saturn Way Limited | Households | 2020 |
| 123BH Limited | Professional & scientific | 2025 |
| 1ST Choice Courier Ltd | Transport & logistics | 2022 |
| 3 Point Productions Limited | Construction | 2016 |
| 3S-SYSTEMS Limited | Professional & scientific | 2004 |
| 3TL Group Ltd | Manufacturing | 2025 |
| 413 Media Limited | Information & communication | 2022 |
| 4TUNE Performance Ltd | Wholesale & retail | 2018 |
| 90 Bedford Road (Management) Limited | Households | 1988 |
| A C T Canine Guarding Limited | Administrative & support | 2009 |
| A 2 B Used Cars Ltd | Wholesale & retail | 2025 |
| A Buyside Perspective Limited | Professional & scientific | 2022 |
| A Hewson Ltd | Professional & scientific | 2008 |
| A Hussain Motors Ltd | Wholesale & retail | 2011 |
| A J T Building Services Ltd | Construction | 2020 |
| A Thousand Words Limited | Information & communication | 2012 |
| A&P Prestige Property Ltd | Real estate | 2025 |
| A. and R. Bruce Limited | Construction | 1987 |
| A.J.Hart and SON Limited | Agriculture & fishing | 1963 |
| A.P. Specialist Doors & Joinery Limited | Construction | 2002 |
| A1 Highways Solutions Ltd | Construction | 2024 |
| A4 Marketing Solutions Ltd | Professional & scientific | 2018 |
| AAP Films Limited | Information & communication | 2022 |
| Abacus Instruments Limited | Manufacturing | 2000 |
| Abacus OIL Experts Limited | Construction | 2019 |
| Abbie Scent Ltd | Manufacturing | 2025 |
| Absolute Asbestos Surveys Limited | Construction | 2012 |
| Acadia Developments Ltd | Extraterritorial | 2022 |
| Accounting Intuition Limited | Education | 1993 |
| Accurate Technologies (UK) Limited | Manufacturing | 2000 |
| Acja Property Holdings Limited | Real estate | 2026 |
| Adamant Property Investment Ltd | Real estate | 2019 |
| Adbd Limited | Information & communication | 2008 |
| ADC Services International Limited | Professional & scientific | 1996 |
| ADC Services Limited | Wholesale & retail | 1993 |
| ADH Heating Services Limited | Professional & scientific | 2003 |
| Adindi (UK) Ltd | Wholesale & retail | 2008 |
| Adindi.Co.Uk Limited | Wholesale & retail | 2007 |
| Advanced Engineering (Middleton) Limited | Professional & scientific | 2011 |
| Advencas Ltd | Extraterritorial | 2024 |
| AE Mixers Limited | Manufacturing | 1968 |
| Aegirbio (UK) Limited | Health & social care | 2020 |
| Aesthetik Ltd | Information & communication | 2008 |
| Aghero Services Limited | Transport & logistics | 2018 |
| Agimi Ltd | Construction | 2017 |
| AIM4SPORT Limited | Arts & recreation | 2006 |
| AIM4SPORT Training Centre Ltd | Arts & recreation | 2014 |
| Airbourne Solutions Limited | Administrative & support | 2006 |
| Airdisplays.Com Limited | Arts & recreation | 2015 |
| AJ Carpentry and Property Services Ltd | Administrative & support | 2022 |
| AJS Signs and Graphics Limited | Construction | 2018 |
| Akwood Property Co.Limited | Real estate | 1964 |
| Albert Electrical Ltd | Construction | 2024 |
| Albion Painters&Decorators Ltd | Construction | 2023 |
| Albone Fabrication Ltd. | Manufacturing | 2017 |
| Albone Racing Development Ltd | Arts & recreation | 2019 |
| Aldgate Construction Company Limited | Construction | 1996 |
| Alexaddarayan Limited | Transport & logistics | 2025 |
| Alexander Drive Services Ltd | Transport & logistics | 2024 |
| Alexiam (UK) Ltd | Wholesale & retail | 2019 |
| Alidas Limited | Information & communication | 2020 |
| Alinuta Ltd | Transport & logistics | 2025 |
| ALL Fill Limited | Professional & scientific | 1984 |
| ALL Green Landscapes Limited | Administrative & support | 2009 |
| Allen Brothers Limited | Real estate | 1927 |
| Allgrowth Estates Ltd | Real estate | 2024 |
| Allgrowth Limited | Administrative & support | 2008 |
| Amber Crane Media Limited | Information & communication | 2017 |
| Amber Howard Ltd | Professional & scientific | 2025 |
| Ambers Sweets Ltd | Wholesale & retail | 2025 |
| Amici Coffee Limited | Hospitality | 2017 |
| AMS Property Ltd | Real estate | 2016 |
| AMT Biggleswade Ltd | Wholesale & retail | 2018 |
| Anago Ltd | Professional & scientific | 2016 |
| Andrea Ashley Health & Beauty Limited | Other services | 2003 |
| Andy Wheatley Services Limited | Other services | 2026 |
| Anime Mystery Loot Ltd | Wholesale & retail | 2026 |
| Anoghalu Ltd | Public administration | 2022 |
| Ansible Consulting Ltd | Information & communication | 2009 |
| Ansonia Consulting Ltd | Professional & scientific | 2013 |
| AOC Construction Ltd | Construction | 2008 |
| Apate Limited | Financial services | 2010 |
| Apient Consulting Limited | Professional & scientific | 2003 |
| App Beginnings Ltd | Information & communication | 2020 |
| Applied Business Computers Limited | Information & communication | 1997 |
| Aquadistri UK Limited | Wholesale & retail | 2000 |
| AR HR Ltd | Administrative & support | 2019 |
| Arbor Work Services Ltd | Administrative & support | 2026 |
| Archers Tool Box Limited | Information & communication | 2014 |
| Arcron Associates Limited | Information & communication | 2020 |
| Arkley Fine Art Fairs Limited | Arts & recreation | 2018 |
| Arneg UK Limited | Manufacturing | 1990 |
| Arroway Space Ltd | Professional & scientific | 2018 |
| Arrows Elite Ltd | Education | 2022 |
| Arte Form Ltd. | Wholesale & retail | 2010 |
| Artistry Thru Dance Limited | Arts & recreation | 2015 |
| ASH Carz Limited | Wholesale & retail | 2025 |
| Ashard Audio Ltd | Information & communication | 2010 |
| Ashtead Technology Midco Limited | Other services | 2016 |