| J Thornton Transport Ltd | Transport & logistics | 2008 |
| J Wood Group Ltd | Construction | 2018 |
| J. & M. Storage Systems Limited | Manufacturing | 1985 |
| J. Hemsworth Bathroom Specialist Ltd | Construction | 2026 |
| J. Hemsworth Wood Burning Stove Specialist Ltd | Construction | 2026 |
| J. Stevens Engineering Limited | Manufacturing | 1989 |
| J.A. Carlile (Farms) Limited | Agriculture & fishing | 1995 |
| J.W Haulage Ltd | Transport & logistics | 2024 |
| JA Modifications Limited | Other services | 2021 |
| Jack Triathlon Ltd | Arts & recreation | 2024 |
| Jackson Independent Consulting Ltd | Information & communication | 2014 |
| Jackson Trustees Limited | Professional & scientific | 2013 |
| Japomia Limited | Information & communication | 2024 |
| Jasap Limited | Construction | 2021 |
| Jasper Silverman Ltd | Professional & scientific | 2024 |
| JBP Farm Services Limited | Administrative & support | 2012 |
| JC Mental Health Ltd | Health & social care | 2025 |
| Jdgm Railway Signalling Training Ltd | Transport & logistics | 2022 |
| JDT Consultancy Services Limited | Professional & scientific | 2011 |
| JE & LB Property Developments Ltd | Real estate | 2020 |
| Jeeves' Kitchen (Breighton) Limited | Hospitality | 2025 |
| Jefferson House Limited | Real estate | 2023 |
| Jemmy Hirst Ltd | Hospitality | 2019 |
| Jemmy Hirst Properties Ltd | Real estate | 2026 |
| Jetty Close Hook RMC Ltd | Households | 2026 |
| JGC Contracts Limited | Construction | 2018 |
| JGTESTING15 Ltd | Construction | 2024 |
| Jim's Pizza Ltd | Hospitality | 2021 |
| Jingletots Limited | Arts & recreation | 2008 |
| JJ Marine LLP | | 2020 |
| JK Sporting Services Limited | Arts & recreation | 2016 |
| JL Asbestos Services Ltd | Professional & scientific | 2023 |
| JNS Bros Ltd. | Construction | 2010 |
| JNS UK Group Limited | Real estate | 2018 |
| Jodat Limited | Real estate | 2026 |
| John a. Hayward Ltd | Construction | 2015 |
| John Beevers (Produce) Limited | | 1970 |
| John Hurt Environmental (UK) Limited | Professional & scientific | 2025 |
| John L.Seaton & Co.,Limited | Professional & scientific | 1893 |
| Jones Cooper Limited | Professional & scientific | 1996 |
| Josh Brown TM Ltd | Other services | 2023 |
| Joy Panda Ltd | Hospitality | 2025 |
| JP Abercrombie Ltd | Professional & scientific | 2019 |
| JPN Investco Limited | Financial services | 2025 |
| JR Alfresco Living Ltd | Wholesale & retail | 2022 |
| JRC Joinery Limited | Construction | 2025 |
| JS Tools Ltd | Wholesale & retail | 2023 |
| Jsea Properties Ltd | Real estate | 2018 |
| Julie Howard Developments Ltd | Real estate | 2005 |
| Julie Howard Ltd | Real estate | 2005 |
| JULIUS-K9 UK Ltd | Wholesale & retail | 2012 |
| Jumilla Property Investments Ltd | Real estate | 2018 |
| Junction Goole Productions Limited | Administrative & support | 2024 |
| Just Commercials Ltd | Wholesale & retail | 2019 |
| Just Order IT Ltd | Transport & logistics | 2022 |
| Just Peel Limited | Administrative & support | 2007 |
| JUST1CALL Property Maintenance Ltd | Real estate | 2025 |
| JUST4RABBITS Ltd | Wholesale & retail | 2015 |
| JWF Consulting Limited | Professional & scientific | 2018 |
| K&K Investment and Trading Ltd | Manufacturing | 2024 |
| K-Mix Ltd | Manufacturing | 2023 |
| Kace IT Limited | Information & communication | 2005 |
| Kacperpol Ltd | Transport & logistics | 2023 |
| KAN Catalin Ltd | Transport & logistics | 2022 |
| KAR WAI Ltd | Hospitality | 2023 |
| Kara (Yorkshire) Limited | Arts & recreation | 2010 |
| Karonia Limited | Wholesale & retail | 2005 |
| Kate Medley Landscaping Services Ltd | Administrative & support | 2026 |
| KAY9 Security Solutions Limited | Administrative & support | 2013 |
| Kaya Catering Ltd | Hospitality | 2025 |
| Kazbrew Limited | Wholesale & retail | 2022 |
| KB Education Ltd | Education | 2022 |
| KBS (Goole) Ltd | Real estate | 2002 |
| Keel (UK) Limited | Professional & scientific | 1997 |
| Keene Optical Limited | Wholesale & retail | 2024 |
| Keldo Furniture Limited | Wholesale & retail | 2025 |
| Keltic Seal Solutions Limited | Manufacturing | 1997 |
| Kenlynn Homes Ltd | Construction | 2024 |
| Kennings Building Supplies Limited | Manufacturing | 2002 |
| Kenny Mann Holdings Ltd | Hospitality | 2026 |
| Kettlewell Group Holdings Ltd | Financial services | 2021 |
| Key Cutting Leeds Market Limited | Manufacturing | 2023 |
| KHF Plumbing & Heating Ltd | Construction | 2020 |
| Kifalz Ltd | Wholesale & retail | 2024 |
| Kingston Signs and Displays Limited | Manufacturing | 2025 |
| Kirklands 1955 Limited | Extraterritorial | 2013 |
| KJL Safety & Health Solutions Ltd | Professional & scientific | 2026 |
| KJT Contracting Limited | Agriculture & fishing | 2024 |
| KK Agency Ltd | Professional & scientific | 2026 |
| KL Management Group Ltd | Administrative & support | 2023 |
| KLF System Management Ltd | Other services | 2015 |
| Klique Ltd | Other services | 2013 |
| Kmen Autos Ltd | Wholesale & retail | 2025 |
| KML Flooring Ltd | Construction | 2011 |
| Knight Engineering Ltd | Professional & scientific | 2026 |
| Knight Gaming Entertainment Ltd | Other services | 2016 |
| Knightwood Holdings (2011) Limited | Real estate | 2011 |
| Knightwood Trust Farms Limited | Agriculture & fishing | 1996 |
| Kora Services Ltd | Transport & logistics | 2025 |
| KPH Sykehouse Ltd | Wholesale & retail | 2019 |