| J. M. Vision & Co Limited | Real estate | 2021 |
| J. Moore Surveying Services Ltd | Construction | 2026 |
| J. Page Construction Limited | Construction | 2013 |
| J. Whiteley Limited | Wholesale & retail | 2020 |
| J.A. Harrington Limited | Construction | 1998 |
| J.A. Kelly Independent Funeral Directors Limited | Other services | 2024 |
| J.A. Richardson (Holdings) Ltd | Financial services | 2017 |
| J.A.J (Yorkshire) Ltd | Construction | 2022 |
| J.A.N Sales Ltd | Wholesale & retail | 2026 |
| J.A.P. Shoes Limited | Other services | 2002 |
| J.Adeyemi Limited | Health & social care | 2026 |
| J.B. Components Limited | Wholesale & retail | 1998 |
| J.B. Wilkinson & Sons (Quality Butchers) Limited | Wholesale & retail | 1975 |
| J.Bagheri Properties Ltd | Real estate | 2021 |
| J.Booth Properties Portfolio Ltd | Real estate | 2019 |
| J.Browne Construction Company Limited | Construction | 1971 |
| J.C. Print Engineers Limited | Manufacturing | 1990 |
| J.C.G. Holdings Ltd | Transport & logistics | 2022 |
| J.C.P.Engineering (Machinery Movement) Ltd | Manufacturing | 2016 |
| J.D. Magrin Ltd | Professional & scientific | 2025 |
| J.D.Matthewman(Textiles)Limited | Real estate | 1972 |
| J.Dixon(Mechanical Services)Limited | Wholesale & retail | 1962 |
| J.E. Henderson Holdings Limited | Financial services | 2021 |
| J.E.L Properties Leeds Limited | Real estate | 2017 |
| J.E.L. Mechanical Services Limited | Construction | 1995 |
| J.F. Finnegan Limited | Construction | 1945 |
| J.F. Mccoll (Sales) Limited | Wholesale & retail | 1978 |
| J.F.D Logistics Yorkshire Ltd | Transport & logistics | 2019 |
| J.G. Etches Limited | Wholesale & retail | 1958 |
| J.G. Jireh Limited | Information & communication | 2022 |
| J.G.B. Insulations Limited | Construction | 2006 |
| J.H. Watson Property Investment Limited | Real estate | 1991 |
| J.Habib (Leeds) Ltd | Real estate | 2026 |
| J.I.G.N Ltd | Information & communication | 2018 |
| J.J.Harrison(Properties)Limited | Real estate | 1963 |
| J.J.S. (Barnburgh) Ltd | Hospitality | 2009 |
| J.J.Stephenson & Co.(Leeds)Limited | Wholesale & retail | 1918 |
| J.K.L. (Leeds) Limited | Construction | 1993 |
| J.L. Hallworth (Decorators) Limited | Wholesale & retail | 1961 |
| J.L.Crabtree Limited | Manufacturing | 1945 |
| J.M. Glendinning (Insurance Brokers) Corporate Limited | Financial services | 2013 |
| J.M. Glendinning (Insurance Brokers) Midlands Limited | Financial services | 2018 |
| J.M. Glendinning (Insurance Brokers) North East Limited | Financial services | 2013 |
| J.M. Glendinning (Insurance Brokers) North West Limited | Financial services | 2019 |
| J.M. Glendinning (Insurance Brokers) North Yorkshire Limited | Financial services | 1977 |
| J.M. Glendinning (Insurance Brokers) South Yorkshire Limited | Financial services | 2013 |
| J.M. Glendinning Community Risk Solutions Limited | Financial services | 2022 |
| J.M. Glendinning Group Limited | Financial services | 2013 |
| J.M. Glendinning Townends (Insurance Brokers) Limited | Financial services | 2013 |
| J.M.A. Landscaping Services Limited | Administrative & support | 2004 |
| J.M.Robinson & SON Limited | Agriculture & fishing | 1955 |
| J.M.Y Building Ltd | Construction | 2019 |
| J.Miles Limited | Transport & logistics | 1959 |
| J.P. Commercial and Claims Ltd | Professional & scientific | 2024 |
| J.P.I Group Limited | Construction | 2019 |
| J.Pullan & Sons Limited | Construction | 1923 |
| J.R.L. (Holdings) Limited | Manufacturing | 1984 |
| J.S. Bramley (Leeds) Limited | Wholesale & retail | 1987 |
| J.S. Foster & Sons (Leeds) Limited | Real estate | 1988 |
| J.S. Marketing Services Limited | Wholesale & retail | 1991 |
| J.S. Miller Contracts Limited | Construction | 1999 |
| J.S. Miller Distribution Limited | Construction | 1999 |
| J.S. ROO Ltd | Construction | 2019 |
| J.S.J. Structures Limited | Manufacturing | 1997 |
| J.S.Miller & Company Limited | Wholesale & retail | 1936 |
| J.T. Mawson Thermal Ceramic Services Limited | Construction | 2025 |
| J.V.D. Engineering Limited | Manufacturing | 1991 |
| J.W. Hillard Limited | Financial services | 2017 |
| J.W. Hinchliffe Limited | Wholesale & retail | 1953 |
| J.W.Plant & Co.Limited | Manufacturing | 1930 |
| J10 Contracts Ltd | Construction | 2013 |
| J2 Coaching Ltd | Education | 2023 |
| J27 Properties Limited | Households | 2020 |
| J3 Analytics Ltd | Information & communication | 2020 |
| J3K IT Services Ltd | Information & communication | 2013 |
| J3T Consulting Ltd | Professional & scientific | 2018 |
| J9 Advisory Limited | Professional & scientific | 2014 |
| J9 Automotive Ltd | Wholesale & retail | 2023 |
| JA & JA Consultancy Limited | Administrative & support | 2023 |
| JA GAS Ltd | Construction | 2009 |
| JA Holdings & Investments Limited | Financial services | 2025 |
| JA Property Investments Yorkshire Ltd | Real estate | 2023 |
| JA Security Ltd | Information & communication | 2025 |
| JA Tasty CIC | Wholesale & retail | 2020 |
| JA Watsons Ltd | Real estate | 2025 |
| JAA Property Solutions Limited | Financial services | 2018 |
| JAB (Leeds) Ltd | Real estate | 2017 |
| JAB Moore Ltd | Health & social care | 2021 |
| Jabberwock Ltd. | Professional & scientific | 2005 |
| Jabbot Ltd | Health & social care | 2025 |
| Jabe Cars Ltd | Wholesale & retail | 2016 |
| Jabe Properties (Yorkshire) Limited | Real estate | 2014 |
| Jabecson Limited | Administrative & support | 2017 |
| Jaber Real Estate Ltd | Real estate | 2024 |
| Jabes Healthcare Ltd | Health & social care | 2025 |
| Jabi Plating Ltd | Administrative & support | 2017 |
| JAC and Sons Group Ltd | Real estate | 2022 |
| Jacca Limited | Wholesale & retail | 2021 |
| Jacek Services Ltd | Transport & logistics | 2019 |
| Jacit Ltd | Information & communication | 2014 |