| JT Media Limited | Information & communication | 2025 |
| JT Psych Services Limited | Health & social care | 2020 |
| Jt&Rg Limited | Professional & scientific | 2024 |
| JTA Foods Ltd | Hospitality | 2026 |
| JTA Inspection Ltd | Construction | 2019 |
| JTB Foods Ltd | Hospitality | 2026 |
| Jtbs Surveying Ltd | Professional & scientific | 2021 |
| Jtdm Testing Limited | Information & communication | 2004 |
| Jtee Limited | Real estate | 2025 |
| JTL Holdings Ltd | Construction | 2025 |
| JTL Lettings Limited | Real estate | 2025 |
| JTM Solutions NE Ltd | Real estate | 2026 |
| Jtmjr | Financial services | 2025 |
| JTO Engineering Ltd | Construction | 2014 |
| Jude Daunt Coaching Limited | Other services | 2021 |
| Jude NCL Limited | Hospitality | 2024 |
| Juice Cabin Limited | Wholesale & retail | 2006 |
| Juiced Music Ltd | Arts & recreation | 2024 |
| Juin Ltd | Professional & scientific | 2025 |
| Jules B Limited | Wholesale & retail | 1986 |
| Jules B Management Limited | Administrative & support | 2015 |
| Julia Betts Ltd | Professional & scientific | 2015 |
| Julia Rodgers Estates Ltd | Real estate | 2025 |
| Julie Scanlon Consultancy Ltd | Administrative & support | 2021 |
| Julie’S Personalised Boutique Ltd | Wholesale & retail | 2026 |
| Jumaa Ltd | Other services | 2024 |
| Jumabhoy Health Consulting Ltd | Professional & scientific | 2026 |
| Jumble Print Designs Limited | Wholesale & retail | 2024 |
| Jumeirah Tours Ltd | Administrative & support | 2019 |
| Jump UP Limited | Information & communication | 2007 |
| Jumping Rivers Ltd | Information & communication | 2016 |
| Jumpkat Ltd | Wholesale & retail | 2023 |
| Jumpupdigital Ltd | Professional & scientific | 2023 |
| Junction 42 Social Enterprises Limited | Health & social care | 2012 |
| Junction Point CIC | Administrative & support | 2021 |
| Junction Point Consultancy Ltd | Administrative & support | 2018 |
| Junction Traffic Management Ltd | Construction | 2019 |
| Junenxi Ltd | Hospitality | 2021 |
| Junk Club Music Ltd | Arts & recreation | 2021 |
| Junk Royale Newcastle Ltd | Hospitality | 2020 |
| Juno Communications Limited | Professional & scientific | 2010 |
| Junon Social Studio Ltd | Professional & scientific | 2025 |
| Junsterik Investments Ltd | Real estate | 2017 |
| Junsterik Ltd | Wholesale & retail | 2009 |
| Juntos Leisure Limited | Hospitality | 2024 |
| Jupiter Homes Ltd | Real estate | 2015 |
| Jurick Consultancy Limited | Information & communication | 2025 |
| Jurispro Limited | Real estate | 2023 |
| Just ADD Tonic Events Ltd | Hospitality | 2022 |
| Just for Cards Limited | Wholesale & retail | 2020 |
| Just Heat Limited | Other services | 2024 |
| Just in Tyne Escape Ltd | Arts & recreation | 2025 |
| Just Johnston Limited | Construction | 2016 |
| Just Johnston Property Developments Limited | Real estate | 2019 |
| Just NOT IT Ltd | Information & communication | 2013 |
| Just Payroll Limited | Administrative & support | 1999 |
| Just Send IT Designs Limited | Wholesale & retail | 2025 |
| Justice Drinks Ltd | Manufacturing | 2024 |
| Justjennings Ltd | Professional & scientific | 2025 |
| JV Roofline and Property Services Ltd | Construction | 2025 |
| Jvdx Limited | Manufacturing | 2025 |
| JVI Technical Services Limited | Professional & scientific | 2026 |
| JVK Doon Trading Ltd | Wholesale & retail | 2023 |
| JVK Matrix Ltd | Information & communication | 2025 |
| Jvsb Ltd | Information & communication | 2025 |
| JW Lifting Services Ltd | Manufacturing | 2019 |
| JW Painting Contractors Limited | Construction | 2025 |
| JWD Property Improvements Ltd | Construction | 2017 |
| Jwhc Investments | Financial services | 2017 |
| JWJ Medical Ltd | Health & social care | 2015 |
| JWK Harrison Ltd | Professional & scientific | 2017 |
| JWM Consultants Ltd | Professional & scientific | 2026 |
| JWW Property Investments Limited | Real estate | 2024 |
| JX & NE Ltd | Financial services | 1981 |
| JX Property Ltd | Real estate | 2023 |
| JYW Ltd | Administrative & support | 2025 |
| JZ Restaurant Ltd | Hospitality | 2025 |
| JZT Limited | Extraterritorial | 1984 |
| K & D Systems Holdings Ltd | Manufacturing | 2014 |
| K & K Retail Stores Limited | Wholesale & retail | 2023 |
| K & K Retails Ltd | Wholesale & retail | 2020 |
| K & L Groundworks Limited | Construction | 2009 |
| K & L Social Cask Ltd | Hospitality | 2025 |
| K & S (Private) Ltd | Health & social care | 2020 |
| K a Moynihan Ltd | Health & social care | 2015 |
| K a Wood and Partners Ltd | Administrative & support | 2021 |
| K and L Traders Ltd | Wholesale & retail | 2025 |
| K and Q Unisex Limited | Other services | 2020 |
| K B Groundwork Services Ltd | Administrative & support | 2025 |
| K Channel Limited | Hospitality | 2023 |
| K Cooperthwaite Services Limited | Professional & scientific | 2014 |
| K D Building Solutions Limited | Construction | 2014 |
| K E Motors Ltd | Wholesale & retail | 2023 |
| K E Offshore Limited | Mining & quarrying | 2019 |
| K Frasers Meats Ltd | Wholesale & retail | 2025 |
| K G M Properties Limited | Real estate | 2014 |
| K Jeffrey Haulage Ltd | Transport & logistics | 2010 |
| K L & Y K Limited | Hospitality | 2021 |
| K L L (NE) Ltd | Hospitality | 2025 |
| K Miah Limited | Households | 2021 |