| 'THE Barn' Childcare Limited | Other services | 2012 |
| Adenglow Limited | Construction | 1983 |
| AF Offshore (North East) Ltd | Professional & scientific | 2021 |
| AFR Darlington Limited | Construction | 2018 |
| Ak&A Holdings Limited | Financial services | 2023 |
| Ak&A Investments Limited | Financial services | 2023 |
| Alexanders Holdings Limited | Wholesale & retail | 2020 |
| Amana Properties Ltd | Real estate | 2025 |
| Apyex Limited | Hospitality | 2018 |
| Arden Fit OUT & Construction Ltd | Professional & scientific | 2021 |
| Armour Coatings Limited | Manufacturing | 2019 |
| ASB Inspection Services Limited | Professional & scientific | 2013 |
| Ashbank Service Limited | Other services | 2016 |
| AW Autoworks Limited | Wholesale & retail | 2011 |
| Bbex Limited | Hospitality | 2021 |
| BCS Extinct Limited | Hospitality | 2019 |
| Bespoke Worktops North East Limited | Manufacturing | 2026 |
| Blackburn Prop Limited | Real estate | 2022 |
| BM Inspection Ltd | Construction | 2024 |
| BOB Alexander Limited | Wholesale & retail | 1964 |
| Bondgate Projects Ltd | Real estate | 2017 |
| Cake Shack Ltd | Wholesale & retail | 2020 |
| Carbonistix Limited | Manufacturing | 2024 |
| CF Cleaning Services Ltd | Administrative & support | 2025 |
| Charbella Properties Ltd | Real estate | 2021 |
| CL Offshore Services Ltd | Professional & scientific | 2017 |
| Cleveland Cascades Limited | Manufacturing | 2003 |
| Complete Solutions (BFD) Ltd | Professional & scientific | 2014 |
| Condortop Limited | Professional & scientific | 2014 |
| Connick Engineering Limited | Professional & scientific | 1981 |
| Coulomb Energy Supply Limited | Energy | 2011 |
| Davidryder Ltd | Financial services | 2019 |
| Design Consultancy Service Limited | Professional & scientific | 2025 |
| Drago North East Ltd | Arts & recreation | 2023 |
| DWN Renewables Ltd | Construction | 2025 |
| Earlsway Holdings Limited | Professional & scientific | 2007 |
| Electrical & Lighting Supplies Ltd | Construction | 2024 |
| ENERGY24 Limited | Energy | 2006 |
| ENERGY24 Services Limited | Extraterritorial | 2009 |
| Fairport Engineering Limited | Professional & scientific | 2008 |
| Fairport Process Equipment Limited | Water & waste | 2009 |
| FEL Holdings Ltd | Professional & scientific | 2016 |
| Filterforce Limited | Professional & scientific | 1982 |
| Five Lamps Trading Ltd | Financial services | 2012 |
| Fivedean Limited | Professional & scientific | 2002 |
| Freelance Agency Ltd | Other services | 2017 |
| FX Investments Ltd | Information & communication | 2024 |
| Gaddas Media Productions Ltd | Arts & recreation | 2024 |
| H Khan Holdings Ltd | Real estate | 2024 |
| Heward Investment Portfolio Limited | Real estate | 2023 |
| Hewcrest Limited | Manufacturing | 2002 |
| Holiday Accommodation Ltd | Real estate | 2023 |
| Humraj Builders Ltd | Construction | 2026 |
| Hunting Holos Ltd | Wholesale & retail | 2024 |
| Ingleby Dog Grooming Limited | Professional & scientific | 2016 |
| Ingleby Pet Supplies Ltd | Wholesale & retail | 2014 |
| J Lane Ltd | Professional & scientific | 2003 |
| J&D Equine Ltd | Professional & scientific | 2024 |
| JA Control and Automation Ltd | Professional & scientific | 2017 |
| JH Business Group Limited | Professional & scientific | 2019 |
| JH Mechanical & Electrical Services Limited | Professional & scientific | 2013 |
| JK Admin Limited | Administrative & support | 2026 |
| JK Tritons Limited | Professional & scientific | 2018 |
| John Morfield Limited | Wholesale & retail | 1962 |
| K Home International Limited | Professional & scientific | 1981 |
| KTJ Communications Ltd | Construction | 2020 |
| L Whittle Limited | Administrative & support | 2020 |
| Landra Services Ltd | Real estate | 2026 |
| Larkins Property Ltd | Real estate | 2026 |
| Leemarr Inspection Services Ltd | Professional & scientific | 2011 |
| Lindy Electronics Limited | Information & communication | 1987 |
| Lindy International Limited | Information & communication | 2001 |
| Linton D.M.C. Limited | Construction | 1989 |
| Love Holidays Book Ltd | Administrative & support | 2025 |
| Lucy Marshall Landscape and Garden Design Ltd | Professional & scientific | 2025 |
| Luxor Leisure Limited | Arts & recreation | 2001 |
| M Sweeney Renewables Ltd | Energy | 2023 |
| M.M. Knitwear (1982) Limited | Real estate | 1981 |
| Mandale Taxis Ltd | Transport & logistics | 2026 |
| Manifesting Money Ltd | Other services | 2022 |
| Masak Ltd | Wholesale & retail | 2024 |
| Mastercopy Limited | Manufacturing | 1989 |
| Mesign Ltd | Professional & scientific | 2021 |
| Metcalfe Developments Limited | Construction | 2019 |
| Mevs 23 Limited | Construction | 2023 |
| Monster Clean Limited | Administrative & support | 2020 |
| Motor Plug Teesside Limited | Wholesale & retail | 2021 |
| Motorhome Hire NE Ltd | Administrative & support | 2024 |
| My Place (Darlington) Ltd | Health & social care | 2011 |
| Next Step Cabling Ltd | Construction | 2025 |
| North Coating&Mechanics Ltd | Wholesale & retail | 2025 |
| OM Foods Extinct Ltd | Manufacturing | 2020 |
| Orchid Bioenergy Group Limited | Financial services | 2008 |
| Orchid Environmental Limited | Water & waste | 2003 |
| Orchid I P Limited | Professional & scientific | 2008 |
| Palladin Limited | Professional & scientific | 1981 |
| Peckish Ltd | Hospitality | 2015 |
| Pizza and Co Thornaby Ltd | Hospitality | 2017 |
| Plimsoll Publishing Limited | Information & communication | 1987 |
| Property and Site Services Ltd | Construction | 2020 |