| A&P Maintenance & Joinery Services Ltd | Construction | 2019 |
| A&T Management and Lettings Ltd | Real estate | 2024 |
| A-G Plumbing & Houses Ltd | Construction | 2021 |
| A-Line Dental Services Limited | Health & social care | 2006 |
| A-Ztech Property Company Limited | Real estate | 1989 |
| A. R. D. Leisure Limited | Arts & recreation | 2013 |
| A.B.L. Electrical Contractors Ltd. | Construction | 2012 |
| A.B1 Sunderland Ltd | Hospitality | 2019 |
| A.D. Goddard Ltd. | Manufacturing | 2012 |
| A.G.E Group Ltd | Manufacturing | 2023 |
| A.H Movie Sculpture Ltd | Arts & recreation | 2023 |
| A.J Clark Ltd | Public administration | 2026 |
| A.J Smartchoice Ltd | Health & social care | 2022 |
| A.Kendal Builders (N/E) Limited | Construction | 2016 |
| A.M. Expert Services Limited | Other services | 2023 |
| A.Milburn and Company,Limited | | 1908 |
| A.N. Sanderson & Co. (Landscape Gardeners) Limited | Administrative & support | 1961 |
| A.P.Tyne&Wear Ltd Limited | Hospitality | 2024 |
| A1 Marine Vessels Limited | Transport & logistics | 2006 |
| A1 Training Co (First AID) Limited | Education | 2012 |
| A1 Velu Catering Ltd | Hospitality | 2025 |
| A2B Properties NE Ltd | Real estate | 2025 |
| A2Z for Educational Services Ltd | Education | 2019 |
| A4 Holdings Ltd | Financial services | 2024 |
| AA Security Products (North East) Limited | Water & waste | 1994 |
| AA to PG Limited | Wholesale & retail | 2021 |
| Aaaap Properties Ltd | Real estate | 2025 |
| Aaasports Academy CIC | Arts & recreation | 2020 |
| Aaasports Limited | Arts & recreation | 2010 |
| Aacle Limited | Information & communication | 2016 |
| Aacs Limited | Construction | 1990 |
| Aacs Services Limited | Construction | 2021 |
| Aadil and Aiyaz Co Ltd | Hospitality | 2023 |
| AAN Pharma Limited | Health & social care | 2013 |
| Aanmdesigns Ltd | Real estate | 2025 |
| Aaran Investment Ltd | Real estate | 2023 |
| Aarjen Enterprise Limited | Wholesale & retail | 2022 |
| Aarjen Investments Limited | Real estate | 2025 |
| Aaryan Chippy Ltd | Hospitality | 2025 |
| AB Heritage Limited | Professional & scientific | 2009 |
| Abbey Lodge (Sunderland) Limited | Hospitality | 2004 |
| Abbeyjo Holdings Ltd | Financial services | 2022 |
| Abbeymed Ltd | Health & social care | 2025 |
| Abbie Taylor Independent Financial Adviser Limited | Financial services | 2025 |
| Abbott Management Services Ltd | Professional & scientific | 2022 |
| Abclassic Photography Ltd | Professional & scientific | 2023 |
| Abila Ltd | Other services | 2017 |
| Ability Consultants Ltd | Professional & scientific | 2020 |
| Ability Supplies UK Limited | Wholesale & retail | 2005 |
| Able (Northern) Limited | Construction | 1995 |
| Able Northern Properties Limited | Professional & scientific | 2025 |
| Able Rail Ltd | Construction | 2021 |
| Above Expectations Limited | Other services | 2004 |
| ABP (North East) Limited | Construction | 2008 |
| Abrt Distribution Ltd | Wholesale & retail | 2024 |
| Absolute Cabaret CIC | Arts & recreation | 2021 |
| Absolute Conversions Ltd | Construction | 2026 |
| Absolute Environmental Compliance Ltd | Water & waste | 2020 |
| Abtexfabricsuk Limited | Wholesale & retail | 2026 |
| ABU Taher Sons Ltd | Hospitality | 2024 |
| AC Consulting Worldwide Ltd | Information & communication | 2026 |
| ACA Systems Support Limited | Information & communication | 1999 |
| Academy Marketing Limited | Administrative & support | 2006 |
| Acceleratephysiotherapyclinics Ltd | Health & social care | 2026 |
| Access Rigging Limited | Mining & quarrying | 2026 |
| Access to Essentials CIC | Arts & recreation | 2026 |
| Accommodation Services (Students) Limited | Extraterritorial | 2012 |
| Accommodation Services (Sunderland) Limited | Extraterritorial | 2012 |
| Accomplished Plumbing Heating & Joinery Services Limited | Construction | 2008 |
| Accountancy Services (NE) Ltd | Professional & scientific | 2014 |
| Acdubsports Ltd | Wholesale & retail | 2024 |
| Aceviral.Com Ltd | Information & communication | 2010 |
| Acme Educare Ltd | Administrative & support | 2026 |
| Acorn Homestays Ltd | Real estate | 2024 |
| Acorn Residential Estates (North Tyne) Limited | Real estate | 2002 |
| Acpp Ltd | Real estate | 2021 |
| Acre Logistics Ltd | Transport & logistics | 2026 |
| ACT Insulation Ltd | Construction | 2013 |
| Action on Dementia Sunderland | Education | 2016 |
| Actions Limited | Education | 2007 |
| Active Families NE CIC | Arts & recreation | 2017 |
| Active Families Training Academy Ltd | Education | 2023 |
| Active Future South Shields CIC | Education | 2024 |
| Active Kids Plus Consultancy Ltd | Professional & scientific | 2022 |
| Active Soles Ltd | Wholesale & retail | 2024 |
| AD Equine Limited | Other services | 2019 |
| AD Multi Sports Limited | Arts & recreation | 2021 |
| AD Property Acquisition Ltd. | Real estate | 2017 |
| AD Property Letting Ltd | Real estate | 2024 |
| Ad-Deen Property Ltd | Real estate | 2026 |
| Adam Pike Ltd | Construction | 2019 |
| Adams Accountants Ltd | Professional & scientific | 2019 |
| Adamski Meiks Construction Ltd | Construction | 2024 |
| Adamson Financial Planning Ltd | Professional & scientific | 2020 |
| Adan GAS Services Ltd | Construction | 2026 |
| Ada’S Cafe Ltd | Hospitality | 2025 |
| ADD (North East) Ltd | Real estate | 2010 |
| Adda of Sunderland Ltd | Hospitality | 2024 |
| Addis Property Holdings Ltd | Real estate | 2020 |
| Adewealth Limited | Health & social care | 2025 |