| JBM Civils and Logistics 24/7 Ltd | Construction | 2023 |
| JC Toys and Collectibles Limited | Wholesale & retail | 2024 |
| Jcps Construction (Yorkshire) Ltd | Construction | 2025 |
| JD Accounting Services Ltd | Professional & scientific | 2024 |
| JDS46 Properties Limited | Real estate | 2020 |
| JDS50 Limited | Financial services | 2021 |
| JDS52 Limited | Wholesale & retail | 2021 |
| JDS53 Limited | Financial services | 2021 |
| JDS54 Limited | Wholesale & retail | 2022 |
| JDS55 Limited | Wholesale & retail | 2022 |
| JET Groundworks Ltd | Construction | 2019 |
| JHS Accounting Ltd | Professional & scientific | 2024 |
| JHS Accounting Team Ltd | Professional & scientific | 2026 |
| Jinac Investments Limited | Financial services | 2017 |
| Jinac Limited | Financial services | 2022 |
| JJ Cars Limited | Wholesale & retail | 2023 |
| JM Shaw Properties Ltd | Real estate | 2025 |
| Jmac Compute Limited | Financial services | 2025 |
| Jmycooling Ltd | Manufacturing | 2023 |
| Joel Pearson Racing Limited | Arts & recreation | 2018 |
| Joesam Holdings Ltd | Financial services | 2021 |
| John Brown (Holdings) Limited | Wholesale & retail | 2009 |
| John Hinchliffe Limited | Manufacturing | 2012 |
| John Jackson Educational Services Ltd | Professional & scientific | 2014 |
| John Simpson & Sons Limited | Wholesale & retail | 1942 |
| John Zekara Ltd Ltd | Wholesale & retail | 2026 |
| Johnson Normanton Limited | Wholesale & retail | 1957 |
| Johnson's Power Ltd | Construction | 2018 |
| Jonas and Jonga Healthcare Ltd | Health & social care | 2021 |
| Jones & Sons Property Group Ltd | Real estate | 2025 |
| Jordan Safety Services Limited | Construction | 2000 |
| Jorvik Pharma Holdings Ltd | Extraterritorial | 2016 |
| Jorvik Pharma Ltd | Wholesale & retail | 2016 |
| Joseph Hughes & Sons Limited | Transport & logistics | 1957 |
| Josh Beever Ltd | Administrative & support | 2017 |
| JPC Utilities Limited | Construction | 2004 |
| JPL NOW Deals Ltd | Wholesale & retail | 2023 |
| JSA Joinery Ltd | Manufacturing | 2020 |
| JT Buildwork Ltd | Construction | 2018 |
| Jufung Ltd | Wholesale & retail | 2026 |
| Just Connect Castleford Ltd | Wholesale & retail | 2024 |
| Jwelsh Residentials Ltd | Real estate | 2024 |
| K & B Driver Hire Ltd | Transport & logistics | 2011 |
| K Dyson Electrical Ltd. | Construction | 2014 |
| K W Electrical Automation Ltd | Construction | 2022 |
| K&L Civils Ltd | Construction | 2026 |
| K&N Sons Limited | Wholesale & retail | 2018 |
| K.A.I. Integrated Services Ltd | Construction | 2014 |
| K.I.K Trucks Rentals Limited | Administrative & support | 2020 |
| Kaira Brothers Ltd | Transport & logistics | 2026 |
| Kalendas Home Improvements Ltd | Construction | 2026 |
| Kamcia Ltd | Transport & logistics | 2024 |
| Karl's K9 Ltd | Agriculture & fishing | 2025 |
| Karl's Kollectible's Ltd | Wholesale & retail | 2025 |
| Kaveru Limited | Health & social care | 2019 |
| Kayus Medics Ltd | Health & social care | 2022 |
| KD Grab Hire Limited | Transport & logistics | 2024 |
| KD Sleeks Ltd | Wholesale & retail | 2024 |
| Kdelicious Products Ltd | Wholesale & retail | 2026 |
| Kebab House Castleford Ltd | Hospitality | 2019 |
| Keel Solutions Ltd | Professional & scientific | 2015 |
| Keestone Contractors Limited | Construction | 2006 |
| Keira Wiles Ltd | Real estate | 2021 |
| Kell Services Ltd | Construction | 2023 |
| Kent Energy Partnerships Limited | Professional & scientific | 2020 |
| Kestrel Carpets (Castleford) Limited | Wholesale & retail | 2010 |
| Kevin Ellis Pontefract Accident Repair Ltd | Wholesale & retail | 2016 |
| KH Sales Group Ltd | Wholesale & retail | 2023 |
| Khrp Group Limited | Professional & scientific | 2023 |
| KIF Ltd | Administrative & support | 2015 |
| Kindred Accounts Limited | Professional & scientific | 2024 |
| Kingsley Child Limited | Construction | 1994 |
| Kingstal Limited | Manufacturing | 2000 |
| Kirens International (Europe) Limited | Wholesale & retail | 2008 |
| Kirens International Limited | Wholesale & retail | 2004 |
| Kirsty Grange Aesthetics Ltd | Other services | 2025 |
| Kitchen Comparison Ltd | Administrative & support | 2024 |
| KK Garage Ltd | Wholesale & retail | 2018 |
| KKH Electrical Ltd | Construction | 2025 |
| KL Electrical (Yorkshire) Ltd | Construction | 2019 |
| KL Executive Travel Limited | Administrative & support | 2025 |
| Klewicz & Co Properties Ltd | Real estate | 2026 |
| KP Hybrids Ltd | Administrative & support | 2025 |
| Kpop Nation Media UK Ltd | Information & communication | 2019 |
| Kpop Nation UK International Ltd | Wholesale & retail | 2019 |
| Kpop Nation UK Ltd | Administrative & support | 2019 |
| KR Foodtopia Limited | Hospitality | 2018 |
| Kris Construction Contracts Limited | Construction | 2024 |
| Krystal Eco-Cleaning Services Ltd | Administrative & support | 2024 |
| Ksenia Building & Construction Ltd | Construction | 2017 |
| KT Therapy Ltd | Health & social care | 2021 |
| Kubiak Transport Ltd | Transport & logistics | 2019 |
| Kuzan Logistics Ltd | Transport & logistics | 2016 |
| Kyle Wood Properties Ltd | Real estate | 2017 |
| Kyonix Ltd | Professional & scientific | 2023 |
| L & Co Trading Ltd | Financial services | 2019 |
| L & M Flooring (Northern) Limited | Construction | 2005 |
| L S Tranz Ltd | Transport & logistics | 2024 |
| L&Co Investments Ltd | Real estate | 2019 |
| L.P.D Property Services Ltd | Administrative & support | 2021 |