| Assured Care 7 Limited | Health & social care | 2019 |
| Astabridge (Holdings) Limited | Manufacturing | 2007 |
| Astabridge Group Limited | Manufacturing | 2024 |
| Astabridge Limited | Manufacturing | 1989 |
| Aston & Smith Mortgage Services Ltd | Financial services | 2004 |
| AT Distribution Services Ltd | Transport & logistics | 2024 |
| AT Operation Solutions Ltd | Transport & logistics | 2026 |
| AT Warehouse Solutions Ltd | Transport & logistics | 2024 |
| Atestateinvestments Limited | Real estate | 2026 |
| Athena Activities Limited | Education | 2023 |
| Atob REG Limited | Wholesale & retail | 2011 |
| Atopo RS Ltd | Wholesale & retail | 2026 |
| Atoussa Ltd | Hospitality | 2025 |
| Aubergine Property Ltd | Real estate | 2021 |
| Audhd Community Embraced CIC | Health & social care | 2024 |
| Aura House 11:11 Ltd | Hospitality | 2026 |
| Aurea Aesthetics Limited | Health & social care | 2017 |
| Aurex Prime Limited | Wholesale & retail | 2026 |
| Aurora Purr Ltd | Agriculture & fishing | 2026 |
| Austin House RTM Company Limited | Households | 2014 |
| Auto A.C. 73 Ltd | Transport & logistics | 2018 |
| Auto AV Garage Limited | Wholesale & retail | 2020 |
| Auto Direct Services (Corby) Limited | Wholesale & retail | 2007 |
| Auto Jakubski Ltd | Construction | 2023 |
| Auto Key Chase Ltd | Wholesale & retail | 2018 |
| Auto Recruit UK Limited | Administrative & support | 2024 |
| Auto Revamp UK Limited | Administrative & support | 2024 |
| Auto Specdivision Ltd | Manufacturing | 2019 |
| Auto Staff Recruitment Limited | Administrative & support | 2024 |
| Auto Technical OC Ltd | Wholesale & retail | 2016 |
| AUTO-CAM85 Ltd | Wholesale & retail | 2016 |
| Auto-Ficek Ltd | Wholesale & retail | 2015 |
| Auto-Union Competitions Limited | Extraterritorial | 2020 |
| Autocleaneruk Limited | Administrative & support | 2025 |
| Autodemon Ltd | Transport & logistics | 2019 |
| Automotive & Nautical Technical Services Ltd | Professional & scientific | 2018 |
| Automotive JP Limited | Wholesale & retail | 2016 |
| Automotive Recruit UK Limited | Administrative & support | 2024 |
| Automotive Solutions Corby Ltd | Wholesale & retail | 2020 |
| Automotive Staff Limited | Administrative & support | 2024 |
| Autoritvar Ltd | Wholesale & retail | 2021 |
| Autoz & Machines Limited | Wholesale & retail | 2023 |
| AVA Trans Limited | Transport & logistics | 2023 |
| Avalon Care Solutions Ltd | Health & social care | 2024 |
| Aviahs Nest Limited | Hospitality | 2024 |
| Aviti Limited | Information & communication | 2009 |
| Avjo Properties Ltd | Real estate | 2022 |
| Avparts Ltd | Administrative & support | 2016 |
| AVR Performance Ltd | Wholesale & retail | 2026 |
| AXB Transport Ltd | Transport & logistics | 2025 |
| Axend Supply Ltd | Wholesale & retail | 2026 |
| Axil Integrated Services Limited | Water & waste | 2014 |
| Axil Property Services Limited | Administrative & support | 2018 |
| Axis Renewable Infrastructure Limited | Administrative & support | 2026 |
| Axum Properties Investment Ltd | Real estate | 2025 |
| Axyra Ltd | Construction | 2026 |
| Axys Tech Ltd | Information & communication | 2024 |
| Ayaan Patel Limited | Real estate | 2026 |
| Ayat Patel Limited | Hospitality | 2022 |
| Ayerkie & Co Ltd | Real estate | 2022 |
| Aylensale Ltd | Wholesale & retail | 2025 |
| Ayse Worldwide Limited | Wholesale & retail | 2025 |
| B R Glazing Ltd | Construction | 2018 |
| B&P TAN Ltd | Administrative & support | 2024 |
| B.A.E Plumbing & Heating Limited | Construction | 2010 |
| B.E.D. (Corby) Limited | Wholesale & retail | 1991 |
| B.F. Brickwork Limited | Construction | 2001 |
| B.G.D. DRY Lining Ltd | Construction | 2019 |
| B.N.J.&Construction Ltd | Construction | 2022 |
| B2RE Limited | Real estate | 2024 |
| BA Truck Ltd | Transport & logistics | 2016 |
| Baba Boon Limited | Transport & logistics | 2018 |
| Babycare Carver Limited | Administrative & support | 2025 |
| Baileys Skip Hire (Northampton) Limited | Water & waste | 2014 |
| Baileys Skip Hire and Recycling Ltd | Water & waste | 2006 |
| Baileys Skiphire ( Corby) Ltd | Extraterritorial | 2013 |
| Bake ME Away Limited | Manufacturing | 2026 |
| Bake ME Happy by Shauni Ltd | Wholesale & retail | 2025 |
| Bakehouse Bistro Ltd | Hospitality | 2025 |
| Balasa CDR Ltd | Transport & logistics | 2015 |
| Bald Bros Motors Ltd | Wholesale & retail | 2025 |
| Balfie Ltd | Construction | 2014 |
| Balkanwins Ltd | Wholesale & retail | 2025 |
| Balloon Studio MK Limited | Wholesale & retail | 2025 |
| Balloonsbyjayna Ltd | Hospitality | 2020 |
| Ballyhoo PR Ltd | Professional & scientific | 2018 |
| Baltic Halal Supermarket Ltd | Wholesale & retail | 2022 |
| Bamly Limited | Wholesale & retail | 2025 |
| Banah Developments Ltd | Construction | 2022 |
| Banah Group Ltd | Real estate | 2022 |
| Bangin' Bites Ltd | Hospitality | 2025 |
| Banmiru Ltd | Other services | 2025 |
| Bannov Ltd | Construction | 2016 |
| Banquet Chocolates Ltd | Wholesale & retail | 2012 |
| Bansal Haulage Ltd | Transport & logistics | 2023 |
| Bappco Ltd | Wholesale & retail | 2020 |
| Bar Monkeys CIC | Health & social care | 2025 |
| Barbara Lucille Chapman Care Services Ltd | Health & social care | 2025 |
| Barbwire Design Limited | Information & communication | 2016 |
| Barclay Specialist Care Ltd | Health & social care | 2017 |