| 100% Performance Guaranteed Limited | Wholesale & retail | 1997 |
| 13 ENG Limited | Professional & scientific | 2018 |
| 14 Mosslea Road (Penge) RTM Company Limited | Households | 2004 |
| 15CR Limited | Real estate | 2026 |
| 166 Cambridge Street Management Company Limited | Households | 2021 |
| 1664 Coaching Ltd | Professional & scientific | 2024 |
| 1820 Property Development Ltd | Real estate | 2018 |
| 30SIXGOLF Ltd | Wholesale & retail | 2026 |
| 33 Architecture Limited | Professional & scientific | 2019 |
| 33 Detail Limited | Professional & scientific | 2023 |
| 4 TEN Limited | Real estate | 1999 |
| 4 Tynedale Terrace Property Management Company Limited | Households | 2001 |
| 4-ELEVEN (International) Limited | Construction | 2014 |
| 88 Holly Avenue Jesmond Management Company Limited | Real estate | 2000 |
| 88SO LLP | | 2024 |
| 95 Citadel Road Limited | Households | 2000 |
| A Consilio Ltd | Information & communication | 2016 |
| A Currah Limited | Other services | 2009 |
| A E Hicks Ltd | Real estate | 2019 |
| A Laing Developments Ltd | Real estate | 2024 |
| A M Hunter Limited | Hospitality | 2013 |
| A Simpson Consulting Ltd | Professional & scientific | 2011 |
| A Wood Idea Limited | Extraterritorial | 2013 |
| A&A Holiday Properties Limited | Hospitality | 2021 |
| A.Walker (Allendale) Limited | Wholesale & retail | 1957 |
| Aaron's Mobile Vehicle Repairs Ltd | Wholesale & retail | 2016 |
| Abbey Plant Ltd | Administrative & support | 2013 |
| Able Tree Services Ltd | Agriculture & fishing | 2025 |
| Absolute Centre Stage Limited | Arts & recreation | 2007 |
| AC Facilities Services Limited | Administrative & support | 2020 |
| Academy Graduations Limited | Professional & scientific | 2010 |
| Accelero Sports Ltd | Manufacturing | 2018 |
| Acomb Letting Rooms Ltd | Hospitality | 2025 |
| Acquis Education Limited | Education | 2017 |
| Active Travel Tynedale (Actt) CIC | Transport & logistics | 2020 |
| AD Medical and Pharma Services Ltd | Health & social care | 2014 |
| Adage IT Ltd | Information & communication | 2022 |
| Adapt (North East) | Administrative & support | 1998 |
| Adsl Heating Ltd | Construction | 2025 |
| Aegis Ventures Holdings Ltd | Financial services | 2025 |
| Aeolian Property Limited | Real estate | 2015 |
| African Photography Safaris Ltd | Professional & scientific | 2025 |
| AGA Industry Ltd | Manufacturing | 2023 |
| AHB Forestry Limited | Agriculture & fishing | 2021 |
| AI Pharmaceutical Services Ltd | Administrative & support | 2026 |
| Aite Architecture Ltd | Professional & scientific | 2024 |
| AJ Beck Onsite Support Ltd | Construction | 2018 |
| Akshay and Ashika Ltd | Health & social care | 2025 |
| Alex Clark Art Ltd | Professional & scientific | 2006 |
| Alexander Carrick Ltd | Manufacturing | 2019 |
| Allen Mills Limited | Real estate | 2005 |
| Allen Valley Catering Limited | Hospitality | 2019 |
| Allendale Brew Company Limited | Manufacturing | 2004 |
| Allendale Butchers and Farm Shop Ltd | Wholesale & retail | 2021 |
| Allendale Community Housing Limited | Real estate | 2007 |
| Allendale Country Club Ltd | Agriculture & fishing | 2018 |
| Allendale Creative Artists Community Interest Company | Arts & recreation | 2007 |
| Allendale Management Limited | Professional & scientific | 2004 |
| Allendale Securities and Investments Limited | Real estate | 2004 |
| Allenheads Contemporary Arts Limited | Education | 2008 |
| Allenheads Trust Limited | Professional & scientific | 2002 |
| Allerwash Farm Buildings Management Company Limited | Real estate | 2005 |
| Allout Adventures Limited | Arts & recreation | 2008 |
| Alpacas in the Woods Ltd | Agriculture & fishing | 2022 |
| Altaer Limited | Other services | 2016 |
| Always Wear Red Limited | Manufacturing | 2015 |
| AMB Project Solutions Ltd | Administrative & support | 2025 |
| Ameliora Financial Ltd | Financial services | 2022 |
| AMR Geomatics Northern Limited | Professional & scientific | 2014 |
| Ancapa Construction Services Ltd | Construction | 2021 |
| Ancient Britain Limited | Arts & recreation | 2016 |
| AND Lisa Presents Ltd | Arts & recreation | 2021 |
| Andrew Heptinstall Photography Limited | Professional & scientific | 2004 |
| Andy's Travels Limited | Administrative & support | 2018 |
| Angela's Law Limited | Hospitality | 2019 |
| Angelfysh Marketing Limited | Professional & scientific | 2006 |
| Anglo-Portuguese Cork Company Limited | Wholesale & retail | 1966 |
| ANH DUC Nails Limited | Other services | 2020 |
| Anton Hill Associates Limited | Other services | 2018 |
| Apple Blossom Childcare Limited | Education | 2009 |
| Appleby Lettings Ltd | Hospitality | 2026 |
| Apprentistart CIC | Administrative & support | 2026 |
| Aprilclean Commercial Limited | Administrative & support | 2015 |
| Aprilclean Limited | Households | 2015 |
| Aquantis Ltd | Professional & scientific | 2009 |
| Aquantis Tidal TEN Limited | Manufacturing | 2024 |
| ARC North Limited | Other services | 2012 |
| Archer Kitchens and Property Maintenance Ltd | Construction | 2025 |
| Archway Apps Limited | Information & communication | 2017 |
| Arctic Tern Films Ltd | Information & communication | 2015 |
| ARK Hair Ltd | Other services | 2024 |
| ARL Property Holdings Limited | Real estate | 2019 |
| Armel Limited | Construction | 2002 |
| Arome Ltd | Information & communication | 2000 |
| Arrow Groundworks Limited | Construction | 2016 |
| Arts-Heritage-Learning Ltd | Arts & recreation | 2022 |
| Ashby View Management Company Limited | Administrative & support | 2002 |
| Ashley Manor Sofas Limited | Wholesale & retail | 2025 |
| Ashpaw Games Ltd | Information & communication | 2025 |
| Ashtree Property Limited | Real estate | 2017 |