| Joel D Kerr Funeral Services Limited | Other services | 2015 |
| Jogo Interims Ltd | Professional & scientific | 2012 |
| John Alton Limited | Construction | 2023 |
| John Lees Services Limited | Construction | 2019 |
| John Paul Rayner Ltd | Wholesale & retail | 2021 |
| John Seymour Land Limited | Real estate | 1997 |
| John Watson Joinery Ltd | Manufacturing | 1982 |
| Joieaux Limited | Wholesale & retail | 2025 |
| Jojoes Branded Merchandise Ltd | Wholesale & retail | 2021 |
| Jonathon DIN Logistics Ltd | Transport & logistics | 2025 |
| Jonny Scott Engineering Ltd | Construction | 2024 |
| Jonny's Cricket Coaching Community Interest Company | Arts & recreation | 2023 |
| Jordan Sanderson Limited | Administrative & support | 2021 |
| Jordan Walton Limited | Professional & scientific | 2025 |
| JP Jointing Services Ltd | Construction | 2018 |
| JP Pipeline Limited | Other services | 2015 |
| Jp's Leisure Ltd | Hospitality | 2018 |
| JPH Electrical Solutions Ltd | Professional & scientific | 2025 |
| JPM Offshore Limited | Construction | 2015 |
| JPM Technical Services Ltd | Construction | 2009 |
| JR Wind Limited | Manufacturing | 2024 |
| JRG Access Ltd | Professional & scientific | 2019 |
| JRH Holdings (NE) Limited | Financial services | 2026 |
| JRP Training Ltd | Professional & scientific | 2003 |
| JS Joinery North East Ltd | Construction | 2025 |
| JSA Electrical Ltd | Mining & quarrying | 2015 |
| Jsaab Ltd | Manufacturing | 2025 |
| JSB Properties Management Ltd | Real estate | 2022 |
| JSC Electrics Limited | Construction | 2005 |
| JSG Consult Ltd | Professional & scientific | 2026 |
| JSK Electro Technical Ltd | Professional & scientific | 2026 |
| JT Industrialuk Limited | Wholesale & retail | 2019 |
| Jtsg Services Limited | Manufacturing | 2019 |
| Juggling Properties Ltd | Real estate | 2020 |
| Juke Limited | Professional & scientific | 2007 |
| Jukes Property Ltd | Real estate | 2025 |
| Julie O'Mariner Limited | Transport & logistics | 2013 |
| Julie's Medusa Lounge Limited | Hospitality | 2026 |
| Just Sorted Company Ltd | Administrative & support | 2025 |
| Justcall Logistics Ltd | Transport & logistics | 2026 |
| JVH Vehicle Hire Limited | Administrative & support | 2015 |
| JW Electech Ltd | Construction | 2026 |
| JW Investment Group Ltd | Real estate | 2020 |
| JW Joinery Services North East Ltd | Construction | 2022 |
| JWR Logistics Ltd | Transport & logistics | 2019 |
| JWW Building Services Limited | Construction | 2005 |
| K and E Properties Limited | Real estate | 2014 |
| K Bailey Electrical Service Ltd | Construction | 2021 |
| K Chippy Hartlepool Ltd | Hospitality | 2025 |
| K J a Fishing Limited | Agriculture & fishing | 2021 |
| K ORD (Grabs) Ltd | Construction | 2017 |
| K ORD Bespoke New Builds Ltd | Construction | 2025 |
| K ORD Property Rentals Ltd | Real estate | 2025 |
| K W Engineering Services U K Limited | Wholesale & retail | 2009 |
| K Winn Building Services Ltd | Construction | 2022 |
| K&L Pest Control Ltd | Other services | 2019 |
| K. Bland Plumbing & Heating Limited | Construction | 2012 |
| K2I Limited | Professional & scientific | 2018 |
| K3 and Partners Properties Ltd | Real estate | 2024 |
| K9 Ocean Guarding Limited | Administrative & support | 2025 |
| K9 Ocean Limited | Administrative & support | 2026 |
| Kane Electromotive Limited | Wholesale & retail | 2023 |
| Kane Specials Limited | Wholesale & retail | 2023 |
| Kapture 24/7 Pest Control & Environmental Services Ltd | Administrative & support | 2025 |
| Karen Louise Ltd | Wholesale & retail | 2019 |
| Karl Cropper Rentals Limited | Real estate | 2024 |
| Kashmir Butt Limited | Hospitality | 2023 |
| KAZ TM Ltd | Other services | 2021 |
| Kaz,Fsb Ltd | Administrative & support | 2026 |
| KB Cable Services Ltd | Construction | 2021 |
| KBC Solutions Ltd | Manufacturing | 2025 |
| KBH Plumbing and Heating Limited | Construction | 2008 |
| KCG Property Management Limited | Construction | 2022 |
| Kconnections Limited | Construction | 2025 |
| Keith Walker 28 Limited | Wholesale & retail | 2012 |
| Kemar Marketing Services Limited | Wholesale & retail | 2006 |
| Kennedy Creative Ltd | Professional & scientific | 2020 |
| Kensteen Consulting Limited | Professional & scientific | 2024 |
| Keta Engineering Limited | Professional & scientific | 2023 |
| Kevin Braithwaite Surveyors Limited | Professional & scientific | 2012 |
| Kevin Wood Building Services Limited | Construction | 2024 |
| KEW Homes NE Limited | Real estate | 2017 |
| Key Consultancy Ltd | Professional & scientific | 2024 |
| Keystone Construction NE Ltd | Construction | 2025 |
| KFK Project Services Limited | Professional & scientific | 2016 |
| KH Electrotechnical Ltd | Energy | 2026 |
| Khan Estates (Teesside) Ltd | Real estate | 2012 |
| KHC Quality & Inspection Ltd | Professional & scientific | 2026 |
| Khdir Holdings Ltd | Real estate | 2019 |
| KIA (North East) Limited | Construction | 2018 |
| Kiddikins Childcare Limited | Education | 2002 |
| Kiernans Properties Limited | Real estate | 2023 |
| Kilmarnock Road Children and Young People Family Resource Centre Limited | Hospitality | 2014 |
| Kind Learning Systems UK CIC | Information & communication | 2024 |
| Kingfield Developments Limited | Construction | 1989 |
| Kingfield Estates Limited | Real estate | 1996 |
| Kingfisher Commissioning Services Limited | Professional & scientific | 2007 |
| Kingfisher Design, Build and Management Ltd | Extraterritorial | 2008 |
| Kingfisher IT Consultancy Limited | Information & communication | 2019 |
| Kingfisher Plant Hire Limited | Administrative & support | 2015 |