| .H.I.S. Bedrooms Ltd | Construction | 2004 |
| 105 High Street Ltd | Real estate | 2025 |
| 11:11 Coffee Aisle Limited | Wholesale & retail | 2024 |
| 13 Base Ltd | Wholesale & retail | 2026 |
| 138 Book-Keeping Ltd | Professional & scientific | 2020 |
| 1885 Media Ltd | Professional & scientific | 2022 |
| 18:36 Skin Ltd | Manufacturing | 2025 |
| 2 Counties Independent Film Festival Ltd | Administrative & support | 2025 |
| 2 Southwell Gardens Management Limited | Households | 1987 |
| 22 Glovers Limited | Administrative & support | 2021 |
| 2BDIGITAL Ltd | Information & communication | 2026 |
| 3/5 Arnold Cottages Management Company Limited | Households | 2003 |
| 304 Alexandra Park Road Residents Company Limited | Households | 2002 |
| 33 Jonathans Limited | Real estate | 2022 |
| 34 / 36 Grove Road Management Company Limited | Real estate | 2014 |
| 365 Creative Limited | Professional & scientific | 2014 |
| 3C Projects Limited | Construction | 2021 |
| 4 Boys on a Boat Ltd | Arts & recreation | 2025 |
| 4C3 Automotive Ltd | Wholesale & retail | 2024 |
| 4FLYING Ltd | Information & communication | 2019 |
| 5ROOMS Ltd | Real estate | 2019 |
| 63 High Street Management Company Limited | Real estate | 2006 |
| 650NED Ltd | Professional & scientific | 2023 |
| 7GW Limited | Administrative & support | 2021 |
| 80 Management Ltd | Professional & scientific | 2024 |
| A & a GAS Service Engineers Limited | Construction | 2004 |
| A & M MK Ltd | Real estate | 2019 |
| A Big O Coffee Ltd | Wholesale & retail | 2019 |
| A Fitter Life Limited | Arts & recreation | 2011 |
| A&T Designs Ltd | Administrative & support | 2014 |
| A&T Supported Living Ltd | Real estate | 2021 |
| A-I Bioprocessing Limited | Professional & scientific | 2025 |
| A.J. & M.A.Hardy Limited | Financial services | 1959 |
| AAA.AMBULANCE3 & Event Care Ltd | Health & social care | 2026 |
| AAA.AMBULANCE3 Ltd | Health & social care | 2022 |
| AAA.AMBULANCE3 Training Academy Ltd | Education | 2026 |
| Aaaml Ltd | Professional & scientific | 2019 |
| AAB Storage Limited | Administrative & support | 2023 |
| Aaes Electrical Services Ltd | Construction | 2013 |
| AAW Enterprises Ltd | Construction | 2018 |
| AB Logistics Consulting Limited | Professional & scientific | 2018 |
| AB Self Storage Limited | Transport & logistics | 2005 |
| Abacus Data Services (UK) Limited | Information & communication | 1986 |
| Abatax Limited | Extraterritorial | 2005 |
| Abbfem Consulting Limited | Information & communication | 2014 |
| Accl Limited | Wholesale & retail | 2008 |
| Accountancy MK Group Ltd | Professional & scientific | 2024 |
| Accounting and Business Development Limited | Professional & scientific | 2000 |
| Acdc International Limited | Professional & scientific | 2017 |
| Ace Window Cleaning Service Ltd | Administrative & support | 2018 |
| Achilleon Consultancy Limited | Other services | 2013 |
| Active Data Installations Limited | Information & communication | 2007 |
| Adams Property Services (MK) Limited | Real estate | 2014 |
| Adders Holdings Ltd | Financial services | 2026 |
| Addictive Creations Ltd | Professional & scientific | 2022 |
| ADG Productions Ltd. | Information & communication | 2011 |
| Adkb Foods Ltd | Hospitality | 2022 |
| ADR Innovations Limited | Professional & scientific | 2022 |
| ADS Construction Consultancy Services Limited | Administrative & support | 2021 |
| ADT Talent Ltd | Information & communication | 2025 |
| Advantage Insight Limited | Extraterritorial | 2014 |
| AE Engineering Ltd | Professional & scientific | 2025 |
| Aerial Management Limited | Arts & recreation | 2025 |
| Aero & Space Ltd | Arts & recreation | 2020 |
| Aerolab Ltd | Manufacturing | 2019 |
| AGPH159 Consulting Ltd | Professional & scientific | 2026 |
| Agrarian ASH Ltd | Administrative & support | 2024 |
| AHA Cars Plus Ltd | Administrative & support | 2018 |
| Airtag Limited | Financial services | 2024 |
| AJW Associates Limited | Professional & scientific | 2023 |
| AKA Roofing & Building Ltd | Construction | 2026 |
| Al&R Property Ltd | Real estate | 2026 |
| Alban Hill Garden Nurseries Limited | Wholesale & retail | 2018 |
| Albert Orchard (Aston Clinton) Management Company Limited | Households | 2014 |
| Albert Roger & Partner France Limited | Wholesale & retail | 2014 |
| Albert Roger Brands Holding Limited | Financial services | 2024 |
| Albert Roger Digital Limited | Wholesale & retail | 2016 |
| Albert Roger Holdings Limited | Financial services | 2016 |
| Albert Roger Limited | Wholesale & retail | 2013 |
| Alchemise Yoga Ltd | Other services | 2018 |
| Alec Events Ltd | Manufacturing | 2019 |
| Alex Bates Nail Artist Ltd | Other services | 2024 |
| Alexandru Gabriel Services Ltd | Construction | 2025 |
| Alfasoft Limited | Information & communication | 2015 |
| Alkb Limited | Construction | 2013 |
| ALL Cleaners Ltd. | Administrative & support | 2020 |
| ALL Saints Church END Projects Limited | Education | 2016 |
| ALL Weather Roofing Ltd | Construction | 2015 |
| Allendale Cottages Limited | Real estate | 2024 |
| Alliance (GW) Limited | Real estate | 2016 |
| ALM Print Limited | Information & communication | 2016 |
| Aloc Ltd | Health & social care | 2016 |
| Alpha Court (Kempston) Limited | Construction | 1991 |
| Alpha Properties (Brighton) Limited | Real estate | 1988 |
| Alpine Fire & Security Ltd | Administrative & support | 2023 |
| Alquest Technical Services Limited | Administrative & support | 1984 |
| Always on Track Ltd | Professional & scientific | 2022 |
| Alyv Ltd | Administrative & support | 2020 |
| AM Detailing Limited | Professional & scientific | 2024 |
| AM Jackson Commercial Services Ltd | Professional & scientific | 2019 |