| James (Wetherby) Limited | Real estate | 1997 |
| James Clay Limited | Professional & scientific | 2006 |
| James Marshall Properties Ltd. | Construction | 1993 |
| James Rayner Limited | Extraterritorial | 2007 |
| James Wilby Limited | Transport & logistics | 2007 |
| Jane Mcdonald Limited | Arts & recreation | 1998 |
| Jantronic Limited | Manufacturing | 2003 |
| JBD Transport Ltd | Transport & logistics | 2004 |
| JBL Quantity Surveying Ltd | Professional & scientific | 2007 |
| JBZ Peels Limited | Real estate | 1999 |
| JC Logistics Ltd | Transport & logistics | 2003 |
| JC Property (NO.2) Limited | Real estate | 2006 |
| JCJ Developments Limited | Construction | 2005 |
| JDM 2010 Limited | Financial services | 2005 |
| JDM Food Group Limited | Manufacturing | 1999 |
| JDM Food Holdings Limited | Financial services | 2021 |
| JDN Consultancy Limited | Professional & scientific | 2007 |
| Jean Walker Limited | Wholesale & retail | 2025 |
| Jebson Construction Limited | Construction | 2005 |
| Jeff Turner Transport & Social Development Consultancy Ltd | Professional & scientific | 2003 |
| Jeremiah Ambler Limited | Professional & scientific | 1970 |
| JEZ Alan Limited | Arts & recreation | 2004 |
| Jigsaw Foods Limited | Manufacturing | 2008 |
| JLA Bidco Limited | Professional & scientific | 2018 |
| JLA Holdco Limited | Financial services | 2018 |
| JLA Midco Limited | Financial services | 2018 |
| JLA Total Care Limited | Administrative & support | 1994 |
| JM Woodward Limited | Construction | 2004 |
| John Brooke & Sons Ltd | Real estate | 1898 |
| John Drury Holdings Limited | Manufacturing | 1949 |
| John Norris & Co. Limited | Professional & scientific | 2003 |
| John Pickard (Hardware) Limited | Wholesale & retail | 1982 |
| John Ransome Accountancy Services Limited | Professional & scientific | 2002 |
| John Shaw & SON (Commercials) Limited | Wholesale & retail | 2003 |
| Jolliffe Cork LLP | | 2004 |
| Jolly Tots Pre-School Nursery Limited | Education | 2007 |
| Joseph Dobson & Sons (Holdings) Limited | Financial services | 2007 |
| Joseph Walker & SON Limited | Wholesale & retail | 1936 |
| Josevecret Ltd | Health & social care | 2025 |
| JSF Steel Erectors & Cladders Limited | Construction | 2008 |
| Julian Berks Computing Limited | Information & communication | 1997 |
| Julian Roche Associates Limited | Wholesale & retail | 1973 |
| Jumping Developments Limited | Professional & scientific | 2004 |
| JY Textiles (Europe) Limited | Administrative & support | 2007 |
| K J P Fabrications Limited | Manufacturing | 2007 |
| K S Vision Care Limited | Wholesale & retail | 2003 |
| Kameel Enterprises Ltd | Wholesale & retail | 2001 |
| Katherine Sharkey Limited | Education | 2006 |
| KAY EN Limited | Health & social care | 2008 |
| KAY Print Limited | Manufacturing | 2004 |
| Keighley Community Nursery Ltd. | Education | 1997 |
| Keighley Waste Management Services Limited | | 2007 |
| Keith Edgar Roofing Ltd | Construction | 2002 |
| Keith Jones School of Motoring Limited | Education | 2002 |
| Keith Longfellow Limited | Construction | 2003 |
| Kellett Properties Ltd | Real estate | 2025 |
| Kemira Chemicals (UK) Limited | Manufacturing | 1967 |
| Key Excellence Limited | Manufacturing | 1997 |
| Keysterne Limited | Real estate | 2002 |
| Keystone ATS Limited | Construction | 2005 |
| Keystone Property Developments Limited | Real estate | 1995 |
| Keystreet Limited | Hospitality | 2003 |
| Kimblemill Limited | Real estate | 1993 |
| Kinddeal Limited | Professional & scientific | 2001 |
| Kindly Housing Company Ltd | Real estate | 2026 |
| King Analytical Limited | Professional & scientific | 2003 |
| Kingclean Limited | Other services | 1991 |
| Kingsley Fitted Furniture Limited | Manufacturing | 1973 |
| Kingston Chemicals (Yorkshire) Limited | Manufacturing | 1992 |
| Kirkdale Engineering Limited | Manufacturing | 1978 |
| Kirkleavington Property Company Limited | Construction | 1964 |
| Kirklees Demolition Services Limited | Wholesale & retail | 1973 |
| KIT 4 Kitchens Limited | Manufacturing | 1994 |
| KNM Freelance Limited | Information & communication | 2007 |
| Kory Bingo Machines Limited | Wholesale & retail | 1997 |
| Koso Kent Introl Limited | Manufacturing | 2005 |
| KS Consultancy Services Ltd | Health & social care | 2018 |
| KSC Car Audio & Equipment Limited | Wholesale & retail | 2006 |
| Kulfi Ice Limited | Professional & scientific | 2004 |
| Kyber-Styl Ltd | Professional & scientific | 1996 |
| L & a Management Limited | Professional & scientific | 1995 |
| L a Wipers Limited | Wholesale & retail | 2003 |
| L Townend Limited | Manufacturing | 2006 |
| L.A.R. Holdings Limited | Professional & scientific | 2002 |
| L.Dennis & Co.,Limited | Professional & scientific | 1921 |
| LA53RED Limited | Professional & scientific | 2007 |
| Laboratory & Containment Solutions Limited | Administrative & support | 2005 |
| Laedan Press Limited | Professional & scientific | 2002 |
| Lakshya Software Solutions Ltd | Information & communication | 2023 |
| Laleham Broadband Limited | Information & communication | 2001 |
| Lamsol (UK) Limited | Administrative & support | 2006 |
| Lancereal Limited | Professional & scientific | 1988 |
| Lanesborough Interiors Limited | Construction | 2007 |
| Lanescroft Properties Limited | Professional & scientific | 1999 |
| Langtree Estates Limited | Real estate | 2003 |
| Langtree Property Services Limited | Real estate | 2002 |
| Lantern Group Holdings Limited | Financial services | 2021 |
| Laptopconnections Limited | Wholesale & retail | 2004 |
| Lawnkeeper UK Limited | Professional & scientific | 2007 |
| Lawton Capital Limited | Manufacturing | 2022 |