| ATL Electrical Services Ltd | Construction | 2018 |
| Atlantic Building Services UK Limited | Construction | 2007 |
| Atlantis Kettering Limited | Hospitality | 2022 |
| Atthy Service Limited | Transport & logistics | 2024 |
| ATZ Transport Limited | Transport & logistics | 2026 |
| Aucle Limited | Households | 2025 |
| Auctionwise Ltd | Wholesale & retail | 2023 |
| Audis Electrical Services Ltd | Manufacturing | 2010 |
| Audrone Limited | Administrative & support | 2014 |
| Augment-It Limited | Information & communication | 2015 |
| Augustus Homes Ltd | Construction | 2022 |
| AUN Medical Ltd | Health & social care | 2009 |
| Aura Avenue Limited | Wholesale & retail | 2025 |
| Aureum Finance Limited | Financial services | 2017 |
| Aureum Insurance Brokers Limited | Financial services | 2024 |
| Aureum Private Finance Limited | Financial services | 2025 |
| Aurora Food Matters Limited | Hospitality | 2018 |
| Aurora Technology (Otgh) Ltd | Information & communication | 2026 |
| Austin Davis Biologics Ltd | Professional & scientific | 2009 |
| Author's Best Limited | Professional & scientific | 2012 |
| Auto Scuff Solutions Ltd | Wholesale & retail | 2013 |
| Autoline Deliveries Ltd | Other services | 2021 |
| Automate Business Solutions Ltd | Wholesale & retail | 2025 |
| Automatic Vehicle Leasing Limited | Administrative & support | 2007 |
| Automoto Classics Ltd | Wholesale & retail | 2016 |
| Auxilium Associates Limited | Financial services | 2018 |
| AV BI Solutions Limited | Information & communication | 2011 |
| AV Builders Limited | Construction | 2014 |
| AV Developments Ltd | Real estate | 2024 |
| AV Fine Food Limited | Wholesale & retail | 2019 |
| Avaia Medical Ltd | Health & social care | 2025 |
| Avalon Court Rothwell Ltd | Households | 2017 |
| Avance Innovations Ltd | Manufacturing | 2024 |
| Avancez Assist Ltd. | Wholesale & retail | 2025 |
| Avem Consulting Limited | Professional & scientific | 2025 |
| Averil Phillips & Family Limited | Other services | 1999 |
| Averil Phillips Properties Ltd | Real estate | 2018 |
| Avery Creative Limited | Professional & scientific | 2016 |
| Avian Heritage Limited | Professional & scientific | 2025 |
| Avondale Sweeps Ltd | Administrative & support | 2017 |
| Avonfield Dairies Limited | Real estate | 1999 |
| AVR Cloud Technologies Ltd | Information & communication | 2026 |
| AW Flight Simulator Services Ltd | Manufacturing | 2021 |
| Awaken Clinic Limited | Health & social care | 2014 |
| Awesome Programming Ltd | Information & communication | 2015 |
| Awwnime Shop Ltd | Wholesale & retail | 2020 |
| Axivantra Consulting Ltd | Professional & scientific | 2026 |
| AXR Logistics Ltd | Transport & logistics | 2026 |
| Ayaans Construction Ltd | Construction | 2024 |
| Ayia Drinks Limited | Wholesale & retail | 2021 |
| AZ General Contractor Ltd | Construction | 2025 |
| AZ Global Services Ltd | Transport & logistics | 2026 |
| Aziza Forerunner School of Leaders Limited | Education | 2024 |
| B & E Nieznansky Investments Ltd | Professional & scientific | 2024 |
| B & J Shears Builders (Northampton) Limited | Other services | 2009 |
| B & R Scaffolding (East Northants) Ltd | Construction | 2018 |
| B and M Pallets Limited | Agriculture & fishing | 2002 |
| B B Electrical (Thrapston) Limited | Administrative & support | 2025 |
| B Brittin Ltd | Professional & scientific | 2006 |
| B C Cooling Limited | Professional & scientific | 2008 |
| B C T C Ltd | Professional & scientific | 2010 |
| B D Highway Services Limited | Construction | 2018 |
| B Grace Associates Limited | Administrative & support | 2022 |
| B M G Logistics Limited | Administrative & support | 2011 |
| B S Leisure Ltd | Hospitality | 2018 |
| B-Tax Advisors LLP | | 2025 |
| B. Eren Mobile Chef Ltd | Hospitality | 2018 |
| B. S. Flats (Irthlingborough) Limited | Households | 1976 |
| B.H.C.A. (Services) Limited | Financial services | 1991 |
| B.L. Caravan Storage Limited | Other services | 2000 |
| B.S. Willis Limited | Wholesale & retail | 2017 |
| B.T.T. Comms Limited | Information & communication | 1997 |
| B.T.T. Communications (Midlands) Limited | Information & communication | 1993 |
| BA Refrigeration Ltd | Construction | 2025 |
| Baan RAO Thai Cuisine Ltd | Hospitality | 2024 |
| Babama Fastfood Limited | Hospitality | 2013 |
| Baby Zzzen Limited | Health & social care | 2023 |
| Bafel Food's Ltd | Wholesale & retail | 2024 |
| Baguettaway Kettering Limited | Hospitality | 2012 |
| Bahal Ltd | Health & social care | 2010 |
| Baheza Ltd | Health & social care | 2015 |
| BAI JIN Limited | Hospitality | 2025 |
| Bakersfield Weldon Limited | Agriculture & fishing | 2015 |
| Bakery Productions Limited | Other services | 2009 |
| BAL Pizza Ltd | Hospitality | 2025 |
| Balloon Your Room Ltd | Other services | 2011 |
| Ballysloe Limited | Professional & scientific | 2015 |
| Bamboodo Ltd | Wholesale & retail | 2026 |
| Bannell Properties Ltd | Real estate | 2015 |
| Bannigan & COX Limited | Construction | 2015 |
| Bannigan & Sons Ltd | Real estate | 2018 |
| Baoji Titanium Industry Co Limited | Manufacturing | 2025 |
| Bar Seven Kettering Ltd | Hospitality | 2019 |
| Baraz Financial Services Limited | Financial services | 2014 |
| Baretrading Limited | Extraterritorial | 2023 |
| Barfoot Ltd | Administrative & support | 2021 |
| Barker and Bass Limited | Extraterritorial | 2011 |
| Barker and Smart Ltd | Real estate | 2016 |
| Barker Homes Abington Ltd | Construction | 2019 |
| Barker Homes Ltd | Professional & scientific | 2019 |