| J S Welch Ltd | Construction | 2022 |
| J Stewart Consultancy Services Ltd | Professional & scientific | 2023 |
| J T Office Interiors Ltd | Wholesale & retail | 2015 |
| J W Paving & Landscaping Limited | Construction | 2016 |
| J W R Nelson Limited | Professional & scientific | 2013 |
| J Welch Ltd | Construction | 2021 |
| J Woodcock Plastering Ltd | Construction | 2026 |
| J&D PAW Supplies Ltd | Wholesale & retail | 2024 |
| J&J Living Ltd | Real estate | 2024 |
| J'S Trade Kitchens and Bedrooms Ltd | Manufacturing | 2015 |
| J. Arkle Ltd | Construction | 2019 |
| J.B Meliora Solutions Ltd | Manufacturing | 2024 |
| J.J. Blair & Sons Limited | Wholesale & retail | 1985 |
| J.M.K Buildforce Ltd | Construction | 2018 |
| J.R.C. Controls Limited | Information & communication | 2002 |
| J.Waterhouse Ltd | Transport & logistics | 2014 |
| J750 Ltd | Wholesale & retail | 2025 |
| JA Beaute Ltd | Other services | 2019 |
| JA Working at Height Ltd | Construction | 2023 |
| JA8 Limited | Hospitality | 2021 |
| Jaap Ltd | Real estate | 2025 |
| Jaced Holdings Ltd | Financial services | 2021 |
| Jack Massey Media Ltd | Information & communication | 2017 |
| Jack Powell Ltd | Financial services | 2019 |
| Jackrabbits PA Limited | Wholesale & retail | 2018 |
| Jackson-Ward Limited | Transport & logistics | 2011 |
| Jack’S Technical Services Ltd | Professional & scientific | 2025 |
| Jagr Holdings Limited | Arts & recreation | 2026 |
| James & Rose Bespoke Upholstery Limited | Manufacturing | 2010 |
| James a Mutton Consulting Limited | Professional & scientific | 2017 |
| James Brewster Financial Services Limited | Financial services | 2013 |
| James Cameron Joinery Ltd | Construction | 2019 |
| James Ford Limited | Construction | 2015 |
| James Middlemiss Ltd | Wholesale & retail | 1993 |
| James Properties NE Limited | Real estate | 2022 |
| James Robinson Limited | Wholesale & retail | 2025 |
| James Stokoe Limited | Professional & scientific | 2022 |
| James Thomas Consultancy Ltd | Professional & scientific | 2013 |
| James' Heating Ltd | Construction | 2015 |
| Jamie Bryant Rope Access Limited | Construction | 2019 |
| Jamie Parcels Ltd | Transport & logistics | 2026 |
| Jamiesons Garage Ltd | Wholesale & retail | 2021 |
| Jamley Business Services Ltd | Professional & scientific | 2025 |
| Jane PIT Storage Ltd | Real estate | 2024 |
| Jared Trans Ltd | Transport & logistics | 2017 |
| Jassat Limited | Health & social care | 2017 |
| Jay's Technical Services Limited | Construction | 2016 |
| Jaykay Toys Limited | Manufacturing | 2014 |
| JB Motor Trading Ltd | Wholesale & retail | 2025 |
| Jb's Access Solutions Limited | Manufacturing | 2025 |
| Jbal Consulting Ltd | Professional & scientific | 2020 |
| JBF Building & Roofing Maintenance Ltd | Construction | 2020 |
| JBL Services Limited | Administrative & support | 2003 |
| JBM Darlington Limited | Wholesale & retail | 2024 |
| JC Digital Solutions Ltd | Construction | 2019 |
| JCB Agricultural & Building Contractor Ltd | Construction | 2011 |
| JCC Kitchen Installations Ltd | Construction | 2017 |
| JCI Heating Limited | Construction | 2004 |
| JD Motor Company (NE) Ltd | Wholesale & retail | 2021 |
| JDC Design & Installation Ltd | Construction | 2011 |
| Jdck Plumbing & Heating Ltd | Construction | 2023 |
| Jdml Construction Limited | Construction | 2025 |
| JDS Chalets Limited | Construction | 2023 |
| JDS Motor Traders Ltd | Wholesale & retail | 2020 |
| JEC Capital Ltd | Real estate | 2020 |
| JEC Management Solutions Limited | Professional & scientific | 2013 |
| Jeeybn Trading Ltd | Wholesale & retail | 2025 |
| Jeffden Limited | Wholesale & retail | 2024 |
| Jehl Ltd | Real estate | 2026 |
| Jejr Ltd | Transport & logistics | 2015 |
| Jeks Analytics Ltd | Information & communication | 2026 |
| JEM 37 Limited | Transport & logistics | 2016 |
| Jemh Consultancy Limited | Professional & scientific | 2022 |
| Jemma Elaine Beauty & Massage Lounge Ltd | Other services | 2013 |
| Jems Helping Hands Ltd | Wholesale & retail | 2019 |
| Jenkinsonn Limited | Wholesale & retail | 2025 |
| Jentra Growth Ltd | Wholesale & retail | 2025 |
| Jervaulx Game Farm Ltd | Agriculture & fishing | 2023 |
| Jervaulx Game Supplies Limited | Agriculture & fishing | 2007 |
| Jessica Karlita Coaching Ltd | Arts & recreation | 2026 |
| Jethro's Barn Ltd | Arts & recreation | 2014 |
| Jewel Kent Ltd | Health & social care | 2015 |
| Jflores Services Limited | Professional & scientific | 2016 |
| JG & B Solutions Ltd | Real estate | 2015 |
| JGB Holdings Ltd | Financial services | 2020 |
| JGB One Limited | Real estate | 2023 |
| JGB Partnership LLP | | 2025 |
| JGB Properties (NE) Ltd | Real estate | 2020 |
| JGB Storage UK Limited | Administrative & support | 2024 |
| JGB Trading Ltd | Wholesale & retail | 2020 |
| JH and JA Nichols Limited | Agriculture & fishing | 2018 |
| JH Roofing and Cladding Ltd | Construction | 2018 |
| JHC Grounworks Limited | Construction | 2021 |
| Jiahuka Food Trade Ltd | Wholesale & retail | 2023 |
| JIG UK Drainage Solutions Ltd | Construction | 2021 |
| JIG UK Plant Hire Ltd | Administrative & support | 2018 |
| Jigsaw Management Services Limited | Financial services | 2025 |
| Jigsaw Waste Management Consultants Ltd | Water & waste | 2024 |
| Jimmy Grabs & Aggs. Ltd. | Transport & logistics | 2017 |
| JJ Gift Books Ltd | Information & communication | 2015 |