| 12906787 Ltd | Manufacturing | 2020 |
| 14 Four Analytics Limited | Professional & scientific | 2014 |
| 15 Courtfield Gardens Limited | Households | 1997 |
| 1510 Holdings Limited | Financial services | 2015 |
| 16687137 Limited | Information & communication | 2025 |
| 18 B Floor RES Area Ltd | Hospitality | 2018 |
| 19TH TEE Catering Ltd | Hospitality | 2025 |
| 2-16 Grenada Crescent RTM Company Limited | Households | 2025 |
| 27 Langthorne Street (Management) Limited | Hospitality | 1999 |
| 2MM Group Ltd | Professional & scientific | 2019 |
| 2TIX Ltd | Professional & scientific | 2019 |
| 363 Fulham Palace Road Limited | Real estate | 1998 |
| 366 Holdings Limited | Financial services | 2020 |
| 3LANCE Tickets Ltd | Wholesale & retail | 2024 |
| 3TEK Recycling Ltd | Water & waste | 2009 |
| 4 Kandles Hardware Paper Shop Ltd | Wholesale & retail | 2023 |
| 403 Nether Street Limited | Real estate | 2022 |
| 44 Communications (UK) Limited | Professional & scientific | 2007 |
| 44 Engage Limited | Professional & scientific | 2021 |
| 44 Holidays Limited | Hospitality | 2021 |
| 44 Properties Limited | Real estate | 2016 |
| 62-64 Tilehurst Road Limited | Real estate | 2015 |
| 74 Priory Park Road Limited | Real estate | 2022 |
| 96-98 High Street Winslow Flat Management Company Limited | Households | 2001 |
| A & N UK Trading Ltd | Wholesale & retail | 2019 |
| A & P Agriscience Ltd | Wholesale & retail | 2008 |
| A & P Resin Limited | Construction | 2025 |
| A Haynes Carpentry Ltd | Administrative & support | 2021 |
| A Lestak Ltd | Transport & logistics | 2019 |
| A&D Carpentry Northants Ltd | Construction | 2023 |
| A&L CAN Clean Ltd | Administrative & support | 2026 |
| A&S Garage Limited | Wholesale & retail | 2022 |
| A&V Repairs Ltd | Wholesale & retail | 2023 |
| A.R.Ludlow Decorating Contractors Limited | Construction | 2015 |
| AAB Aviation Ltd | Manufacturing | 2020 |
| Aaron Barnes Transport Limited | Transport & logistics | 2022 |
| Abbeymar Ltd | Extraterritorial | 2008 |
| Abbliss Limited | Wholesale & retail | 2005 |
| Accent Lighting Ltd | Wholesale & retail | 2010 |
| Accountal Ltd | Professional & scientific | 2017 |
| Achieveit Contracts Limited | Information & communication | 2013 |
| Acorn ABA Limited | Professional & scientific | 2017 |
| ACUR8 Engineering Ltd | Wholesale & retail | 2023 |
| AD Bivol Ltd | Hospitality | 2025 |
| Adam Confue Paving Services Limited | Construction | 2015 |
| Adam Rendering Services Ltd | Construction | 2024 |
| Adams Vehicle Solution Ltd | Wholesale & retail | 2025 |
| Adamski Services Limited | Transport & logistics | 2018 |
| Addeo Property Investments Ltd | Construction | 2025 |
| Aden Consultancy Limited | Professional & scientific | 2011 |
| ADI Baza Ltd | Transport & logistics | 2013 |
| Adjei Motors Limited | Wholesale & retail | 2025 |
| ADL Trans Ltd | Transport & logistics | 2020 |
| Adriser Couriers Ltd | Transport & logistics | 2021 |
| Adroitis Accounting Ltd | Professional & scientific | 2017 |
| ADS Property Services Ltd | Construction | 2022 |
| Advanced Logistc Ltd | Transport & logistics | 2022 |
| Advanced People Strategies Limited | Professional & scientific | 2004 |
| AEDIFICIUM41 Limited | Real estate | 2020 |
| AES Reflections Limited | Other services | 2019 |
| AET Systems Ltd | Manufacturing | 1998 |
| AF Northants Ltd | Financial services | 2018 |
| Affinity Executive Limited | Professional & scientific | 2020 |
| Aftur Limited | Administrative & support | 2026 |
| Agency Care Training Solutions Limited | Administrative & support | 2019 |
| AGH Design & Media Ltd | Professional & scientific | 2020 |
| AGS Northants Ltd | Construction | 2026 |
| Aiden J Ltd | Construction | 2023 |
| AIM High Horsemanship LLP | | 2021 |
| Air Conditioning Installations UK Limited | Energy | 2011 |
| AJ Cushions Ltd | Manufacturing | 2025 |
| AJH Engineering Services Ltd | Professional & scientific | 2023 |
| AJJ Associates Ltd | Other services | 2010 |
| AKO UK Limited | Wholesale & retail | 1995 |
| Aland Krdd Ltd | Wholesale & retail | 2025 |
| Alarmfix Ltd | Construction | 2018 |
| Alco Filters (UK) Limited | Wholesale & retail | 1994 |
| Aldo Fabrication Ltd | Manufacturing | 2018 |
| Aldor Solutions Ltd | Manufacturing | 2019 |
| Alert INS Limited | Financial services | 2026 |
| Alfie's Gents Stylists Ltd | Other services | 2003 |
| Alice Travel Solutions Ltd | Administrative & support | 2025 |
| ALL Parking Solutions Ltd | Administrative & support | 2020 |
| Alltranz Removals and Storage Limited | Transport & logistics | 2018 |
| Allweigh Scales Limited | Manufacturing | 2011 |
| ALP Pharm Ltd | Professional & scientific | 2008 |
| Alpha-Cure Group Limited | Manufacturing | 2019 |
| Alpha-Cure Holdings Limited | Manufacturing | 2005 |
| Alpha-Cure Limited | Manufacturing | 1996 |
| Alphaclock Limited | Information & communication | 1999 |
| Alphascootz Pro Ltd | Wholesale & retail | 2024 |
| Alpine Carpet Warehouse Limited | Wholesale & retail | 2007 |
| Alt-R Services Limited | Administrative & support | 2006 |
| Alternative Plans Limited | Extraterritorial | 2022 |
| Altoba Holdings Ltd | Financial services | 2025 |
| ALU Architectural Art Europe Holdings Ltd | Professional & scientific | 2017 |
| Aluminium Federation Limited | Other services | 1962 |
| Always ASK WHY Ltd | Professional & scientific | 2019 |
| Amalia NEK Trans Ltd | Transport & logistics | 2018 |
| Amazing Fireworks Ltd | Wholesale & retail | 2005 |