| Iron Hill International Limited | Professional & scientific | 2024 |
| Island Farm Enterprises Limited | Hospitality | 2019 |
| J & J Holdings (York) Limited | Hospitality | 2018 |
| J & JJ Holdings Ltd | Real estate | 2019 |
| J Brown Residential Ltd | Real estate | 2026 |
| J Group Platinum Limited | Real estate | 2021 |
| J Hagar Limited | Agriculture & fishing | 2012 |
| J R T Yorkshire Limited | Professional & scientific | 2025 |
| J S Renewables Limited | Construction | 2018 |
| J Smith Enterprise Ltd. | Agriculture & fishing | 2019 |
| J. Thackray & Sons (Steel Structures) Limited | Construction | 1985 |
| J.A. Cussons Limited | Agriculture & fishing | 1977 |
| J.Liber Limited | Manufacturing | 1933 |
| JAC Racing LLP | | 2016 |
| Jacksons Wold Eggs Limited | Agriculture & fishing | 2024 |
| James Lindenberg Limited | Wholesale & retail | 2023 |
| James RAE Ltd | Wholesale & retail | 2025 |
| James Sullivan Ltd | Arts & recreation | 2018 |
| James Wattrus Mrics Ltd. | Professional & scientific | 2023 |
| JAR of Ltd | Extraterritorial | 2024 |
| JC Motors & Plant Limited | Wholesale & retail | 2023 |
| Jeba Bengal Ltd | Hospitality | 2013 |
| Jefferson Investments (York) Limited | Financial services | 2020 |
| Jefferson Properties (York) Limited | Real estate | 2018 |
| Jeffrey Contracting Limited | Agriculture & fishing | 2017 |
| JET Republic (Europe) Limited | Transport & logistics | 2014 |
| JFR Masonry and Renovations Limited | Construction | 2021 |
| JH Westleigh Limited | Arts & recreation | 2024 |
| Jitterbugs Nursery Limited | Administrative & support | 2003 |
| Jjam Limited | Financial services | 2026 |
| JK Consulting (North Yorkshire) Ltd | Construction | 2024 |
| JKM Cropco Ltd | Agriculture & fishing | 2015 |
| JLK Editorial Limited | Information & communication | 2024 |
| Jlls Consultancy Ltd | Professional & scientific | 2024 |
| JM Douglas Limited | Agriculture & fishing | 2023 |
| JM Packaging Limited | Administrative & support | 1998 |
| JMD Technologies (2010) Limited | Extraterritorial | 2010 |
| JMD Technologies Limited | Manufacturing | 2014 |
| Joanna Mason Racing Ltd | Arts & recreation | 2023 |
| Joel Preston Golf Limited | Education | 2025 |
| John Birkett Ltd | Real estate | 2022 |
| Jonathan Wurr Limited | Administrative & support | 2016 |
| Jor-Event Limited | Administrative & support | 2017 |
| Jordan Farrington Commercials Limited | Wholesale & retail | 2021 |
| Jordan, Jordan & Jordan Limited | Real estate | 2021 |
| Jorvik Chilli Ltd | Wholesale & retail | 2024 |
| JP Mason & Sons Limited | Extraterritorial | 2011 |
| JP Timber Limited | Agriculture & fishing | 2022 |
| JRC Enterprises Limited | Financial services | 2015 |
| JRD Media Productions Ltd | Administrative & support | 2022 |
| JS Graphixx Ltd | Manufacturing | 2018 |
| JS Workwear and Embroidery Limited | Wholesale & retail | 2024 |
| Just Stone Holdings Ltd | Real estate | 2024 |
| K F Scott Limited | Construction | 2005 |
| K Midgley Builders Ltd | Construction | 2024 |
| Kantara Limited | Information & communication | 1996 |
| Karro Food Frozen Limited | Manufacturing | 2014 |
| Karro Food Group Limited | Financial services | 2012 |
| Karro Food Stoke Limited | Manufacturing | 2014 |
| Karro Property Limited | Real estate | 2014 |
| Kaye Property Holdings Limited | Real estate | 2024 |
| Keble Park Construction Ltd. | Construction | 2022 |
| Keiras Kastles Limited | Other services | 2022 |
| Kemps on the Corner Ltd | Wholesale & retail | 2024 |
| KEN Monkman Solutions Limited | Education | 2013 |
| Kench Holdings Ltd | Financial services | 2025 |
| Kettering Property Rentals Ltd | Households | 2025 |
| KFS & BCD Limited | Financial services | 2026 |
| Kingspan Metl-Con Limited | Financial services | 1996 |
| Kirby Grindalythe Management Company Limited | Households | 2007 |
| Kirby Wold Farming Ltd | Agriculture & fishing | 2021 |
| Kirkham and Firby Estates Ltd | Real estate | 2021 |
| Kirstie Lumley Mortgage Broker Ltd | Financial services | 2022 |
| Knapton Properties Ltd | Households | 2022 |
| Kolgecaj Limited | Administrative & support | 2014 |
| Kullasoft Ltd | Information & communication | 2016 |
| Kumppanit Limited | Professional & scientific | 2024 |
| L Egerton Racing Ltd | Arts & recreation | 2017 |
| LA Duquessa Investments Limited | Real estate | 2024 |
| Lamb Carpentry and Construction Ltd | Construction | 2026 |
| Land Rovers of Yorkshire Limited | Wholesale & retail | 2021 |
| Landscape Research Centre Limited | Health & social care | 1984 |
| Lanes Accessories Limited | Extraterritorial | 2025 |
| Langton Farms Limited | Agriculture & fishing | 1978 |
| Langton Hall Language School Limited | Education | 2010 |
| Large Outdoors Limited | Arts & recreation | 2009 |
| Lazlar 53 Ltd | Hospitality | 2019 |
| LC Apex Engineering Ltd | Manufacturing | 2024 |
| Ldmh Partners Ltd | Professional & scientific | 2022 |
| Leap Industries Ltd | Construction | 2023 |
| Learn to Rock Ltd | Education | 2007 |
| Leartech Limited | Information & communication | 2019 |
| Leavening Rise Management Company Limited | Households | 1999 |
| Leisure Vehicle Franchising Ltd | Wholesale & retail | 2014 |
| Leisure Vehicle Property Ltd | Financial services | 2019 |
| Lemon & Pine Limited | Real estate | 2025 |
| Leogue Consulting Limited | Information & communication | 2022 |
| Lilling Green Farm Ltd | Agriculture & fishing | 2025 |
| Lindenberg Forest Products Ltd | Real estate | 2016 |
| Lintons Yorkshire Limited | Professional & scientific | 2025 |