| 2020 Lettings Ltd | Real estate | 2020 |
| 2031 Productions Ltd | Information & communication | 2026 |
| 21 Dresses Limited | Wholesale & retail | 2013 |
| 26 Buer Road Management Limited | Real estate | 2008 |
| 2RM Motorsport Ltd | Extraterritorial | 2024 |
| 3 Flavours Brackley Ltd | Hospitality | 2026 |
| 3D Make ME Ltd | Manufacturing | 2026 |
| 422 Store Ltd | Wholesale & retail | 2024 |
| 586 Enterprise Limited | Professional & scientific | 2008 |
| 586 Group Limited | Professional & scientific | 2008 |
| 586 Technology Limited | Professional & scientific | 2008 |
| 676 Limited | Wholesale & retail | 2023 |
| 76 Automotive Ltd | Wholesale & retail | 2024 |
| 794 Creative Ltd | Information & communication | 2023 |
| 90 High Street Brackley Limited | Real estate | 2015 |
| A and S Drains Ltd | Construction | 2020 |
| A B Computing Solutions Limited | Information & communication | 2012 |
| A G Grossi Limited | Construction | 2006 |
| A G NEL Limited | Professional & scientific | 2013 |
| A J Gibson Holdings Limited | Financial services | 2018 |
| A L Thompson Ltd | Real estate | 1978 |
| A&G Hospitality Ltd | Hospitality | 2025 |
| A&G Security Services Ltd | Administrative & support | 2024 |
| A-642 Architecture Ltd | Professional & scientific | 2025 |
| A. W. Duncombe & SON Limited | Wholesale & retail | 2005 |
| A1 Locums Limited | Administrative & support | 2004 |
| A2B Cabs Brackley Ltd | Transport & logistics | 2018 |
| A2B Logistics EU Services Limited | Transport & logistics | 2008 |
| A5 Data Limited | Information & communication | 2020 |
| AB Automotive Consultancy Limited | Manufacturing | 2025 |
| AB Memorabilia Ltd | Wholesale & retail | 2023 |
| Abby Investments Ltd | Construction | 2023 |
| Abigail Jane Ltd | Information & communication | 2021 |
| Abington Supermarkets Limited | Wholesale & retail | 2004 |
| ABK Property Investing Ltd | Real estate | 2021 |
| Absolute Tree Care LLP | | 2004 |
| AC the AC X Champion Media Ltd | Information & communication | 2026 |
| Accent Percussion Community Interest Company | Arts & recreation | 2023 |
| Ace Estates Holdings Limited | Real estate | 2024 |
| Acer Resourcing Limited | Information & communication | 2006 |
| Achieve Mindset Coaching Ltd | Professional & scientific | 2025 |
| Acorn Cleaning Limited | Administrative & support | 2007 |
| Acquire Consultancy Ltd | Other services | 2022 |
| AD 27 Properties Ltd | Real estate | 2024 |
| Adaptable Underfloor Heating Limited | Wholesale & retail | 2024 |
| Adder Consulting Limited | Information & communication | 2022 |
| ADG Property Services Ltd | Administrative & support | 2024 |
| Adrian Morrow Architects Limited | Professional & scientific | 2011 |
| ADS Dental Ltd | Health & social care | 2016 |
| Adult Transition Services Ltd | Health & social care | 2019 |
| Advanced Deep Clean Solutions Ltd | Administrative & support | 2021 |
| Aesthetic Medical Practitioners Limited | Professional & scientific | 2015 |
| AFD Construction Limited | Construction | 2003 |
| AFD Plant Limited | Administrative & support | 2019 |
| Afinity Homes Ltd | Construction | 2023 |
| AGM Lettings Ltd | Real estate | 2022 |
| Ahad Housing Limited | Real estate | 2026 |
| AI Business Insights Limited | Information & communication | 2024 |
| AI London Investments Ltd | Real estate | 2017 |
| Aifer Limited | Wholesale & retail | 2024 |
| Aimee Bracken Photography Ltd | Professional & scientific | 2022 |
| Aire Serv Limited | Professional & scientific | 2013 |
| AIT Consulting Ltd | Information & communication | 2014 |
| AJ Security Consultancy Ltd | Information & communication | 2022 |
| Aj-B Accountancy Limited | Professional & scientific | 2015 |
| AJU Limited | Transport & logistics | 2008 |
| AK19 Limited | Financial services | 2016 |
| AKA Events Brackley Ltd | Hospitality | 2021 |
| AKA Law Ltd | Professional & scientific | 2015 |
| Akehurst & EVE Limited | Administrative & support | 2017 |
| Albatros Creative Limited | Information & communication | 2015 |
| Alberto Solera Ltd | Real estate | 2018 |
| Albion Street Management Company Limited | Real estate | 1997 |
| ALC Property Retreats Ltd | Real estate | 2025 |
| Alex Osborne Jewellery Ltd | Wholesale & retail | 2010 |
| Alexander Lauren Investments Ltd | Financial services | 2017 |
| Alexander Niall Ltd. | Financial services | 2017 |
| Algar Estates Limited | Financial services | 2021 |
| Alistaire Hulls Property Services Limited | Real estate | 2016 |
| ALL About the Beer Ltd | Wholesale & retail | 2020 |
| ALL in One Locksmith Ltd | Administrative & support | 2024 |
| ALL the Good Stuff Ltd | Hospitality | 2021 |
| Alliance Empire Corporation Ltd | Financial services | 2021 |
| Allied Electrical Recovery Limited | Construction | 2001 |
| Almeida Cleaning Services Ltd | Administrative & support | 2026 |
| Almig UK Limited | Wholesale & retail | 2008 |
| Almond Abodes Ltd | Real estate | 2025 |
| Aloeworks Limited | Wholesale & retail | 2014 |
| Alpha IT and Management Consulting Ltd | Information & communication | 1998 |
| Alpine Cleaning Management Limited | Administrative & support | 2017 |
| AMA & I Properties Ltd | Real estate | 2025 |
| Amaka Studio Ltd | Administrative & support | 2020 |
| Amanah Consortium Limited | Real estate | 2013 |
| Ambrosden Developments Limited | Construction | 2019 |
| Amelia Lane London Ltd | Wholesale & retail | 2025 |
| Amethyst Associates Limited | Information & communication | 1991 |
| Amethyst Support Services Limited | Information & communication | 1995 |
| Ametrine Consulting Limited | Administrative & support | 2017 |
| Amity Theatre Ltd | Arts & recreation | 2024 |
| Andomo Limited | Wholesale & retail | 2016 |