| JOE Davidson Renewables Ltd | Construction | 2025 |
| JOE Storey Property Ltd | Construction | 2025 |
| John Donkin Solicitors Ltd | Professional & scientific | 2008 |
| John Grooms | Health & social care | 1911 |
| John Jones Butchers Limited | Wholesale & retail | 2014 |
| John Mcguire Ltd | Construction | 2023 |
| John Moody Investments Limited | Real estate | 2002 |
| John Reed Associates Consultancy Ltd | Information & communication | 2018 |
| John Silcock Gastroenterology Limited | Health & social care | 2016 |
| Johnson Electric International (UK) Limited | Manufacturing | 1967 |
| Johnson Wright (Flooring) Limited | Construction | 1991 |
| Johnston Dental Ltd | Financial services | 2023 |
| Johnston Varty Developments LLP | | 2017 |
| Johnstone Medical Services Limited | Health & social care | 2014 |
| Joined Capital Limited | Real estate | 2025 |
| Jomir Limited | Real estate | 2020 |
| JON Engineering Limited | Professional & scientific | 2017 |
| JON Kelly Garage Services Ltd | Wholesale & retail | 2012 |
| Jonathan Antony Art Limited | Other services | 2011 |
| Jonathan Baker Architect Ltd | Professional & scientific | 2019 |
| Jones Global Consulting Limited | Professional & scientific | 2019 |
| Jones HR Services Limited | Administrative & support | 2016 |
| Jonsigns Limited | Manufacturing | 2006 |
| Jordan Flooring Limited | Construction | 2024 |
| Joseph James JCM Ltd. | Construction | 2022 |
| Joseph Joshua Properties Limited | Households | 2025 |
| Joshmat Electrical Services Ltd | Construction | 2017 |
| Joymichael Ltd | Health & social care | 2022 |
| JQ Investment Ltd | Financial services | 2019 |
| Jrad NDT Ltd | Other services | 2019 |
| JRC Entertainments Limited | Arts & recreation | 2019 |
| JS Access&Renewable Ltd | Manufacturing | 2026 |
| JS BD Solutions Ltd | Administrative & support | 2025 |
| JSP Management (NE) Ltd. | Real estate | 2019 |
| JSS (NE) Ltd | Financial services | 2020 |
| JT 4 Limited | Professional & scientific | 2016 |
| JT Engineering Services (NE) Limited | Professional & scientific | 2013 |
| JT Taverns (South Shields) Limited | Real estate | 2018 |
| JTC Taste Ltd | Hospitality | 2026 |
| Jude Downing Content Marketing Ltd | Information & communication | 2017 |
| Julany Enterprise Ltd | Wholesale & retail | 2026 |
| Julian Finance Limited | Financial services | 2025 |
| Julian's Leisure Limited | | 1992 |
| Julie Higgs Hunters Ltd | Hospitality | 2006 |
| Junc Limited | Real estate | 2017 |
| Just Bathrooms (Newcastle) Limited | Construction | 2006 |
| Just Foils Ltd | Wholesale & retail | 2026 |
| Just Inspections Limited | Administrative & support | 2019 |
| Just Peachy Ltd | Wholesale & retail | 2024 |
| Just Signs and Lighting Limited | Other services | 2005 |
| Just XRM Limited | Information & communication | 2021 |
| Jutely Ltd | Real estate | 2016 |
| Jwdm (NE) Limited | Construction | 2024 |
| JWF (Holdings) Limited | Financial services | 2005 |
| JWF (North East) Ltd | Financial services | 2018 |
| Jwmotionmedia Ltd | Professional & scientific | 2025 |
| JX Technology Services Limited | Information & communication | 2008 |
| Jzka LLP | | 2022 |
| K & B Signs Limited | Manufacturing | 2015 |
| K & B Turner Limited | Real estate | 2012 |
| K & C Beauty Ltd | Other services | 2019 |
| K & J Solutions Ltd | Financial services | 2018 |
| K Beauty Salon Ltd | Other services | 2022 |
| K G M Refrigeration Limited | Manufacturing | 2002 |
| K J Fasteners Limited | Wholesale & retail | 2006 |
| K J Plastering & DRY Lining Contractors Limited | Construction | 2018 |
| K J Plastering and Rendering Contractors Ltd | Construction | 2020 |
| K L K Ltd | Other services | 2019 |
| K O'Hara Ltd | Professional & scientific | 2012 |
| K S Designs Limited | Manufacturing | 2006 |
| K S Healthcare Ltd | Health & social care | 2019 |
| K T Laverty Limited | Professional & scientific | 2013 |
| K&K NCL Services Ltd | Administrative & support | 2023 |
| K&M Investment Properties Ltd | Real estate | 2021 |
| K'S Homehelp Limited | Health & social care | 2017 |
| K.E Locum Ltd | Wholesale & retail | 2022 |
| K.M Trading (NE) Limited | Professional & scientific | 2018 |
| K1 Barberz Ltd | Other services | 2025 |
| K3 Industrial Solutions Limited | Professional & scientific | 2025 |
| K3 Property Solutions Ltd | Real estate | 2025 |
| K32 Digital Limited | Professional & scientific | 2025 |
| KA & AO Limited | Wholesale & retail | 2009 |
| Kaaboo Ltd | Wholesale & retail | 2021 |
| Kabani Fashion Limited | Wholesale & retail | 2025 |
| Kaboogie Leisure Limited | Arts & recreation | 2015 |
| Kadita Limited | Real estate | 2021 |
| Kahj Ltd | Health & social care | 2018 |
| KAI Driveways & Groundworks Ltd | Construction | 2011 |
| KAI Food 888 Ltd | Hospitality | 2024 |
| KAI Foods Ltd | Wholesale & retail | 2015 |
| KAI Utilities Limited | Construction | 2023 |
| Kaif Ayoub Consultancy Ltd | Professional & scientific | 2025 |
| Kalmer Counselling Limited | Education | 2013 |
| Kalyna Ltd | Real estate | 2020 |
| Kamm Estates Ltd | Real estate | 2023 |
| KAN Hanesher Ltd | Information & communication | 2025 |
| Karibi Healthcare Limited | Health & social care | 2021 |
| Karm Design Limited | Professional & scientific | 2014 |
| Karpet Mills Limited | Wholesale & retail | 2013 |
| Karu Property Holdings Ltd | Real estate | 2025 |