| JAY Franco Europe Limited | Wholesale & retail | 2017 |
| JAY Johnstone and Co Limited | Information & communication | 2014 |
| JAY Tech Solutions Ltd | Information & communication | 2011 |
| Jayco Holdings Limited | Arts & recreation | 2023 |
| Jayco Recruitment Limited | Administrative & support | 2018 |
| Jayliv Holdings Ltd | Financial services | 2023 |
| Jayliv Leisure Ltd | Hospitality | 2026 |
| Jaymatic Limited | Administrative & support | 2016 |
| JAYRONN1 Limited | Transport & logistics | 2024 |
| Jays Electrics & Construction Ltd | Construction | 2025 |
| JAZ Autos Ltd | Wholesale & retail | 2026 |
| Jazz Co-Op | Arts & recreation | 2015 |
| Jazz Hair Design Ltd | Other services | 2015 |
| Jazz North-East Limited | Arts & recreation | 1978 |
| JB Associates (Consultants) Ltd | Professional & scientific | 2019 |
| JB Fashion Ltd | Wholesale & retail | 2026 |
| JB Fashion Retail Ltd | Wholesale & retail | 2026 |
| JB Pinnacle Ltd | Construction | 2026 |
| JB Research Limited | Professional & scientific | 2018 |
| JBC 4 Ltd | Real estate | 2023 |
| JBC 5 LLP | | 2023 |
| JBC 6 Ltd | Real estate | 2024 |
| JBC Management Solutions Ltd | Professional & scientific | 2009 |
| Jbholidays Ltd | Administrative & support | 2026 |
| JBL Blue Ltd | Wholesale & retail | 2020 |
| JBT Rental Limited | Hospitality | 2022 |
| JC & IC Ltd | Hospitality | 2025 |
| JC Auto Valet Ltd | Administrative & support | 2022 |
| JC Construction Management Ltd | Professional & scientific | 2022 |
| JC Estates (NE) Ltd | Real estate | 2021 |
| JC Estates Property Ltd | Real estate | 2026 |
| JC Formwork Limited | Construction | 2013 |
| JC Gardening Limited | Professional & scientific | 2021 |
| JC Global Limited | Wholesale & retail | 2016 |
| JC Heating Solutions Ltd | Construction | 2021 |
| JC HSE Consultancies Ltd | Construction | 2026 |
| JC Legal Consulting Ltd | Professional & scientific | 2020 |
| JC North Shields LLP | | 2025 |
| JC Rigging & Lifting Ltd | Construction | 2026 |
| JC Walton Investments Limited | Real estate | 2024 |
| JCD Rentals Ltd | Real estate | 2022 |
| Jcfs Investments Limited | Professional & scientific | 2022 |
| Jchks Ltd | Financial services | 2026 |
| Jcjk Limited | Hospitality | 2007 |
| JCM (Newcastle) Limited | Wholesale & retail | 2005 |
| JCM Properties Limited | Real estate | 2023 |
| JCP Consulting Engineers Limited | Professional & scientific | 2012 |
| JCP Light Haulage Limited | Transport & logistics | 2012 |
| JCP NE Group Ltd | Professional & scientific | 2025 |
| JCR Stores (Cowgate) Ltd | Wholesale & retail | 2020 |
| JCR Stores (Metro Centre) Ltd | Wholesale & retail | 2020 |
| JCR Stores Limited | Real estate | 2020 |
| JCS Transport Solutions Ltd | Transport & logistics | 2012 |
| JCT Property Investments Ltd | Real estate | 2018 |
| Jct:Co Limited | Wholesale & retail | 2022 |
| JD Air Solutions Ltd | Construction | 2026 |
| JD Blade Care Ltd | Information & communication | 2016 |
| JD Car Dealers Ltd | Wholesale & retail | 2025 |
| JD Essentials Limited | Wholesale & retail | 2021 |
| JD Investco Limited | Financial services | 2024 |
| JD MED Ltd | Health & social care | 2024 |
| JD Octopus Limited | Real estate | 2022 |
| JD Phones Limited | Wholesale & retail | 2020 |
| JD Political Communications Ltd | Professional & scientific | 2021 |
| JDA Therapy Ltd | Health & social care | 2017 |
| Jdcs Group Ltd | Construction | 2026 |
| Jddk Architects Ltd | Professional & scientific | 1994 |
| JDI Ventures Limited | Real estate | 1999 |
| JDL GAS & Plumbing Services Ltd | Construction | 2021 |
| JDM Homes NE Limited | Real estate | 2025 |
| JDR Project Solutions Ltd | Professional & scientific | 2014 |
| JDS Accident Repair Centre Limited | Wholesale & retail | 2025 |
| JDS Joinery &Shopfitting Limited | Manufacturing | 2026 |
| JDT Construction Services Ltd | Other services | 2011 |
| JDT Films Ltd | Other services | 2026 |
| Jdwni Limited | Real estate | 2025 |
| Jebb Brothers Ltd | Financial services | 2020 |
| Jebb Metals Recycling Ltd | Wholesale & retail | 2024 |
| Jecco Energy Consulting Limited | Professional & scientific | 2016 |
| Jefpac Limited | Professional & scientific | 2003 |
| JEL Active LLP | | 2012 |
| Jellyfish Energy Limited | Energy | 2014 |
| Jellyfish Holdings Limited | Financial services | 2025 |
| Jellyfish Mobile Limited | Information & communication | 2026 |
| Jellyfish Money Limited | Administrative & support | 2025 |
| JEN Bernard Interiors Limited | Professional & scientific | 2025 |
| Jenkins Homes Limited | Real estate | 2017 |
| Jenkins Mortimer Ltd | Real estate | 2020 |
| Jenn Garside Illustration Ltd | Arts & recreation | 2025 |
| Jennifer Tate Copywriting Limited | Information & communication | 2017 |
| Jensens Limited | Real estate | 2005 |
| Jeonse Limited | Real estate | 2021 |
| Jerath Estates LLP | | 2026 |
| Jerath Holdings Limited | Administrative & support | 2019 |
| Jermaine Limited | Real estate | 2018 |
| Jermy Trading Ltd | Financial services | 2025 |
| Jerram Falkus Construction Limited | Construction | 1964 |
| JES 2 LET Limited | Real estate | 2025 |
| Jesco Inspection Ltd | Mining & quarrying | 2019 |
| Jesforth Nurseries Ltd | Real estate | 2026 |