| 10AY 2 Ltd | Wholesale & retail | 2025 |
| 11 Squares Ltd | Professional & scientific | 2018 |
| 112 Secure (Automotive) Ltd | Wholesale & retail | 2023 |
| 112 Secure Limited | Other services | 2011 |
| 167 Holdings (North East) Ltd | Real estate | 2025 |
| 16814823 Limited | Real estate | 2025 |
| 180 Degrees Consulting Durham CIC | Health & social care | 2021 |
| 1811 Limited | Manufacturing | 2017 |
| 1STOCK Limited | Manufacturing | 2024 |
| 2 Active Club Ltd | Wholesale & retail | 2024 |
| 2020 Scaffolding Solutions Limited | Construction | 2020 |
| 24 Winterwell Road Limited | Households | 2012 |
| 25 Market Place Limited | Real estate | 2021 |
| 2N Properties Ltd | Real estate | 2023 |
| 3 Dental Manufacturing Ltd | Manufacturing | 2018 |
| 3 of Cups Durham Ltd | Hospitality | 2024 |
| 313 Commercial Ltd | Financial services | 2020 |
| 313 Financial Ltd | Professional & scientific | 2016 |
| 32ONGO Limited | Professional & scientific | 2025 |
| 360 Geoscience Archaeology & Heritage Ltd | Professional & scientific | 2019 |
| 360 Property Group Limited | Real estate | 2016 |
| 360 Upkeep Ltd | Construction | 2025 |
| 3P Group Limited | Transport & logistics | 2015 |
| 3TO1RESCUE Ltd | Public administration | 2023 |
| 40 Winks Durham Ltd | Hospitality | 2020 |
| 42 Marygate Limited | Hospitality | 2023 |
| 466353 Limited | | 1949 |
| 47 Northbailey Ltd | Hospitality | 2025 |
| 4M Partners Limited | Health & social care | 2023 |
| 4S AI Ltd | Real estate | 2024 |
| 5 Star Caravan Storage Limited | Transport & logistics | 2021 |
| 517EPA Limited | Extraterritorial | 2014 |
| 52 Fordwych Road NW2 Limited | Households | 1996 |
| 555INC Ltd | Other services | 2025 |
| 5TH Element JIU Jitsu Limited | Arts & recreation | 2019 |
| 5TORONTO Properties Limited | Real estate | 2024 |
| 67 Eats and Treats Ltd | Hospitality | 2026 |
| 7 Dimensions Wellness CIC | Other services | 2025 |
| 78A Hanover Road Freehold Limited | Real estate | 2023 |
| 8 Saddler Street Ltd | Real estate | 2023 |
| 83 Gilesgate Management Company Limited | Households | 2000 |
| 9 Saddler Street Ltd | Real estate | 2023 |
| 91 Bedale Road Ltd | Real estate | 2025 |
| 9MOTORS Ltd | Wholesale & retail | 2024 |
| @Thegreen Ltd | Manufacturing | 2019 |
| A & a Crane & Haulage Ltd | Transport & logistics | 2016 |
| A & a Pearson Countrywide Ltd | Wholesale & retail | 2018 |
| A & H Technology Limited | Construction | 2021 |
| A & H Testing Limited | Professional & scientific | 2011 |
| A & J Thompson Scaffolding Ltd | Construction | 2021 |
| A & M Granite Solutions Ltd | Wholesale & retail | 2017 |
| A B Taylor Properties Ltd | Real estate | 2020 |
| A C Rowntree Limited | Construction | 2024 |
| A C Utilities (North East) Ltd | Construction | 2018 |
| A Chester Roofing Limited | Construction | 2025 |
| A Crosby Construction Limited | Construction | 2016 |
| A F Motor Services (Durham) Limited | Wholesale & retail | 2012 |
| A H Property Assets Ltd | Construction | 2022 |
| A Holmes Groundworks Ltd | Construction | 2019 |
| A Jackson Accountants Limited | Professional & scientific | 2026 |
| A LEE Construction Services Limited | Construction | 2026 |
| A Leigh Construction Ltd | Construction | 2025 |
| A M Conservation Ltd | Arts & recreation | 2025 |
| A Month From NOW Ltd | Health & social care | 2020 |
| A P Property Developmentments Ltd | Real estate | 2026 |
| A SIX Ninety One Warranties Limited | Wholesale & retail | 2019 |
| A Taste of Scotland Limited | Agriculture & fishing | 1984 |
| A Usher Holdings Ltd | Financial services | 2025 |
| A Williams Groundworks Limited | Construction | 2020 |
| A Wright Flooring Services Ltd | Construction | 2021 |
| A&D Traditional Turkish Barber Ltd | Other services | 2023 |
| A&M Property Management NE Ltd | Real estate | 2026 |
| A'S Healthcare Limited | Health & social care | 2014 |
| A-Apps Limited | Information & communication | 2014 |
| A. & C. Associates Limited | Professional & scientific | 2009 |
| A. LEE Paving Limited | Construction | 2007 |
| A.B. Health Limited | Health & social care | 2009 |
| A.F.R Pipelines Ltd | Energy | 2020 |
| A.I.F Plastering Ltd | Construction | 2024 |
| A.K Forks Limited | Construction | 2018 |
| A.N.Zee Limited | Administrative & support | 2019 |
| A.R.Webster Ltd | Administrative & support | 2022 |
| A.T. Construction & Maintenance Co. Ltd | Construction | 2004 |
| A1 Ecology Limited | Professional & scientific | 2012 |
| A1 Windscreens (NE) Ltd | Wholesale & retail | 2015 |
| A2B Cleaning (NE) Ltd | Administrative & support | 2019 |
| A2B Serviced Accommodation Ltd | Hospitality | 2021 |
| A2Z Property Associates Ltd | Real estate | 2023 |
| A4 & C Ltd | Construction | 2024 |
| A4AO Limited | Professional & scientific | 2017 |
| A690 Prep Centre Limited | Wholesale & retail | 2019 |
| AA Logistics Ltd | Transport & logistics | 2026 |
| AA Progressive Properties Limited | Real estate | 2023 |
| AA Rentals Limited | Administrative & support | 2026 |
| AA Thrustboring Services Limited | Construction | 2003 |
| Aa.Jj.Ss Ltd | Construction | 2025 |
| AAA Caring Caretaker Limited | Administrative & support | 2015 |
| AAA Cleaning Solutions Ltd | Administrative & support | 2023 |
| AAA.AA.A1.ACOMPLETE Plumbing & Heating Services Limited | Wholesale & retail | 1999 |
| AAI Rice Worldwide Ltd | Information & communication | 2025 |