| Aspect Glazing Ltd | Construction | 2012 |
| Aspect Project Solutions Limited | Information & communication | 2021 |
| Aspect Psychology Ltd | Education | 2020 |
| Aspectual Ltd | Professional & scientific | 2019 |
| Aspen Brown Limited | Construction | 2007 |
| Aspen Consultancy Limited | Financial services | 2000 |
| Aspen Rural Consultancy Limited | Real estate | 2018 |
| Aspers (Northampton) Limited | Hospitality | 2025 |
| Aspexan Limited | Extraterritorial | 2018 |
| Aspire Business Corporation Ltd | Professional & scientific | 2022 |
| Aspire Inventories Ltd | Real estate | 2018 |
| Aspire Orthodontics Limited | Health & social care | 2017 |
| Aspire Productions C.I.C. | Information & communication | 2022 |
| Aspire SEN Tutoring Ltd | Education | 2025 |
| Aspire Therapeutic Services Ltd | Health & social care | 2026 |
| Aspire Wellness Community Ltd | Arts & recreation | 2012 |
| Aspire Youth Services Ltd | Hospitality | 2016 |
| Aspire-Igen Group Ltd | Education | 1995 |
| Aspiring Ground CIC | Manufacturing | 2021 |
| Aspley Reproductions & Interiors Ltd | Wholesale & retail | 2012 |
| Asps Properties Ltd | Real estate | 2018 |
| Aspyre Sync Hub Limited | Information & communication | 2025 |
| ASQ International Ltd | Transport & logistics | 2016 |
| Asquaredu Ltd | Wholesale & retail | 2026 |
| Asquith Court Holdings Limited | Professional & scientific | 1990 |
| Asquith Court Nurseries Limited | Professional & scientific | 1995 |
| Asquith Nurseries Developments Limited | Education | 2002 |
| Asquith Nurseries Limited | Education | 2004 |
| Asrar Ltd | Hospitality | 2010 |
| Assaab Investments Ltd | Real estate | 2012 |
| Asset GAS Services Ltd | Construction | 2018 |
| Asset Global Accountants Ltd | Professional & scientific | 2020 |
| Asset Global Direct Ltd | Wholesale & retail | 2020 |
| Asset Insurance Solutions Ltd | Financial services | 2013 |
| Assetgrove Lettings Limited | Real estate | 2002 |
| Assetory Limited | Professional & scientific | 2026 |
| Assets Holdings Ltd | Real estate | 2024 |
| ASSIMIL8 Holdings Limited | Financial services | 2023 |
| ASSIMIL8 Limited | Information & communication | 2006 |
| Assirklann Ltd | Health & social care | 2016 |
| Assist Care Team Limited | Health & social care | 2012 |
| Assist Insurance Services Limited | Financial services | 2005 |
| Assist Your Lift Ltd | Manufacturing | 2020 |
| Assist-Uk Ltd | Education | 2025 |
| Assisted Care Services Limited | Health & social care | 2017 |
| Assisted Living Care Group Ltd | Health & social care | 2019 |
| Assisted Living Care Ltd | Health & social care | 2021 |
| Assisted Living Housing C.I.C. | Real estate | 2019 |
| Assistsol Ltd | Wholesale & retail | 2025 |
| Associated Engineering Services Holdings Limited | Financial services | 2012 |
| Associated Engineering Services Limited | Administrative & support | 1982 |
| Association of Northamptonshire Supplementary Schools Limited | Education | 2009 |
| Assopong & Co Limited | Wholesale & retail | 2008 |
| Assura IQ Ltd | Information & communication | 2026 |
| Assure Property and Design Ltd | Manufacturing | 2026 |
| Assured Hope C.I.C. | Hospitality | 2026 |
| Astbury Tree Care Limited | Agriculture & fishing | 2024 |
| Astek Solutions Limited | Information & communication | 2011 |
| Aster Recruitment Ltd | Health & social care | 2024 |
| Astin Point Management Limited | Real estate | 2006 |
| Aston Homes Northampton Ltd | Households | 2025 |
| Astons Legal Limited | Professional & scientific | 2010 |
| Astontek Limited | Other services | 2025 |
| Astounding Agency Limited | Information & communication | 2024 |
| Astro Access Services Limited | Construction | 2012 |
| Astro Access Specialists Ltd | Construction | 2025 |
| Astro CBD Club Ltd | Manufacturing | 2019 |
| Astrocyte Limited | Information & communication | 2011 |
| Astrocyte Quant Limited | Professional & scientific | 2011 |
| Astteria Ltd | Other services | 2015 |
| Astute Services Limited | Professional & scientific | 2001 |
| Asum Express Ltd | Transport & logistics | 2023 |
| Asymmetric Intelligence Ltd | Information & communication | 2023 |
| Asyncorigins Ltd | Wholesale & retail | 2018 |
| Aszr Ltd | Transport & logistics | 2023 |
| AT Consultancy and Advocacy Ltd | Health & social care | 2022 |
| AT Darci’S Limited | Hospitality | 2026 |
| AT One Therapy and Wellbeing Ltd | Public administration | 2023 |
| AT Surveys Limited | Professional & scientific | 2021 |
| AT Tours Ltd | Administrative & support | 2023 |
| AT2 Residences Limited | Real estate | 2025 |
| ATA (Architecture) Limited | Professional & scientific | 2016 |
| ATA (Residential) Limited | Professional & scientific | 2022 |
| Atakent LLP | | 2021 |
| Atallo Ltd | Professional & scientific | 2018 |
| Atalp Ltd | Transport & logistics | 2023 |
| Atartech Professionals & Consultancy Ltd | Information & communication | 2023 |
| Ataur Rahman Limited | Manufacturing | 2025 |
| Atbillboorman Ltd | Other services | 2011 |
| ATC Sipro Ltd | Financial services | 2017 |
| ATC Transport Company Ltd | Transport & logistics | 2023 |
| Atecy Developments Ltd | Construction | 2018 |
| Atelier Wcmf Ltd | Professional & scientific | 2013 |
| Atex Premier Cleaning Ltd | Manufacturing | 2020 |
| ATEX360 Ltd | Information & communication | 2024 |
| Atexsto Ltd | Administrative & support | 2011 |
| Atfd Ltd | Information & communication | 2023 |
| ATG (Midlands) Limited | Professional & scientific | 2025 |
| ATG Scientific Limited | Professional & scientific | 2011 |
| Athari Community Interest Company | Education | 2023 |