| Join & Build Ltd | Construction | 2025 |
| Jole Plant Hire Limited | Administrative & support | 2016 |
| Jollie Partners Limited | Extraterritorial | 2022 |
| Jolly Good Communities C.I.C. | Education | 2018 |
| Joly Ltd | Public administration | 2019 |
| JON Garden Buildings Limited | Manufacturing | 1995 |
| Jon-Leuven Ltd | Professional & scientific | 2015 |
| Jones Consultancy Ltd | Professional & scientific | 2025 |
| Jonny Lythgoe Ltd | Professional & scientific | 2024 |
| Jordan Rabjohn Ltd | Arts & recreation | 2022 |
| Joseph Dexter Limited | Wholesale & retail | 2026 |
| Joseph Healthcare Ltd | Health & social care | 2020 |
| Joseph James Care Ltd | Administrative & support | 2024 |
| Joseph Locke Properties Ltd | Real estate | 2020 |
| Josh Shillito Transport Limited | Transport & logistics | 2024 |
| Josh Wilks Limited | Professional & scientific | 2017 |
| Journey Further Group Limited | Professional & scientific | 2021 |
| Journey Further Limited | Professional & scientific | 2016 |
| Journey Futures CIC | Education | 2026 |
| Jowitt Bros. Limited | Manufacturing | 2003 |
| Joy Hong 2024 Ltd | Hospitality | 2024 |
| JP Harkin Solutions Ltd | Wholesale & retail | 2024 |
| JP Optics Limited | Information & communication | 2022 |
| JP Scaffolding Solutions Ltd | Construction | 2020 |
| Jpapautomotive Ltd | Construction | 2021 |
| JPF Elec Ltd | Construction | 2019 |
| JPL Diversified Ltd | Professional & scientific | 2019 |
| JPM Construction Ltd | Administrative & support | 2016 |
| Jpss Ltd | Professional & scientific | 2026 |
| JPW Consulting Ltd | Professional & scientific | 2011 |
| JPW Yorkshire Limited | Construction | 1997 |
| JR Refinishing Limited | Wholesale & retail | 2022 |
| JR Scott Consultancy Limited | Professional & scientific | 2026 |
| JRA Ceramics Ltd | Construction | 2025 |
| JRB Designs Limited | Professional & scientific | 1997 |
| JRB GAS Services Ltd | Construction | 2026 |
| JRB Properties & Developments Limited | Real estate | 2026 |
| Jrbdesigns Structures Ltd | Professional & scientific | 2020 |
| JRC Engineering Limited | Construction | 2005 |
| JRC Housing Management Ltd | Real estate | 2022 |
| JRF Construction Solutions Limited | Construction | 2020 |
| JRF Utilities Limited | Construction | 2023 |
| Jrjh Software Ltd | Information & communication | 2021 |
| JRL Ltd | Construction | 2024 |
| JRL Plumbing & Heating Maintenance Limited | Construction | 2010 |
| JRN Contracting (Yorkshire) Limited | Other services | 2008 |
| JRS Enterprises Northern Ltd | Construction | 2024 |
| Jrsl Properties Ltd | Real estate | 2018 |
| JS Rentals (Yorkshire) Limited | Real estate | 2023 |
| JSA (SY) Ltd | Hospitality | 2026 |
| JSA Timber Products Limited | Wholesale & retail | 2018 |
| JSD Mechanical Services Limited | Professional & scientific | 2014 |
| JSG Leisure Limited | Hospitality | 2020 |
| JSR Building Contractors Ltd | Construction | 2022 |
| JSS Installations (Rotherham) Limited | Construction | 2008 |
| JT Assessment & Consultancy Ltd | Professional & scientific | 2025 |
| JT Construction (Yorkshire) Limited | Construction | 2017 |
| JT Rail Services Limited | Transport & logistics | 2014 |
| JT Trucks Ltd | Wholesale & retail | 2020 |
| JTC Property Group Ltd | Real estate | 2025 |
| JTD Recycling Ltd | Wholesale & retail | 2025 |
| Jtekt Automotive England Ltd | Manufacturing | 1990 |
| JTG Utilities Ltd | Information & communication | 2024 |
| Jubb Consulting Ltd | Professional & scientific | 2024 |
| Jubb Electrical Ltd | Construction | 2024 |
| Juhaszstudios Ltd | Other services | 2025 |
| Julie Killey Send Services Limited | Professional & scientific | 2024 |
| Julie's Courtyard Ltd | Hospitality | 2020 |
| Julie's Delivery Solutions Limited | Transport & logistics | 2023 |
| July Moon Limited | Professional & scientific | 2008 |
| Jumbo Self Drive Limited | Wholesale & retail | 1988 |
| Junction 36 Car Sales Limited | Wholesale & retail | 2024 |
| Jungle Tattoo Supplies Ltd | Wholesale & retail | 2014 |
| Junkyard Labs Limited | Wholesale & retail | 2025 |
| Juno Finance UK Limited | Financial services | 2012 |
| Just Connect Ltd | Wholesale & retail | 2021 |
| Just Cook Limited | Hospitality | 2019 |
| Just Kitchens Ltd | Wholesale & retail | 2012 |
| Just Renewables Ltd | Construction | 2011 |
| Just Roofing Limited | Extraterritorial | 2001 |
| Just Service UK Ltd | Professional & scientific | 2007 |
| Justin Bags Limited | Administrative & support | 2017 |
| Justin Kent Limited | Construction | 2025 |
| Justprintingminis Ltd | Manufacturing | 2026 |
| JW Decorators(Uk) Ltd | Construction | 2022 |
| JW Developments and Investments Ltd | Real estate | 2026 |
| JW Motor Co Yorkshire Ltd | Wholesale & retail | 2023 |
| JW Survey & Design Limited | Professional & scientific | 2010 |
| JW3 Ltd | Wholesale & retail | 2024 |
| JWJ Finance Limited | Professional & scientific | 2017 |
| K & a GAS Solutions Ltd | Construction | 2019 |
| K & a Partners Limited | Arts & recreation | 2016 |
| K & D Simpson Roofing & Building Supplies Limited | Construction | 2012 |
| K & D Transport(Barnsley) Limited | Transport & logistics | 2024 |
| K & K Potts Limited | Wholesale & retail | 2003 |
| K & S Pet Care Services Limited | Professional & scientific | 2008 |
| K Allingham Services Limited | Administrative & support | 2012 |
| K D Decorating Limited | Construction | 2016 |
| K G Access Solutions Limited | Construction | 2017 |
| K J Investments Yorkshire Limited | Real estate | 2018 |