| Island Monkey Shop Ltd | Wholesale & retail | 2025 |
| Ivbalizn Ltd | Wholesale & retail | 2021 |
| J & D Hazard Limited | Administrative & support | 2015 |
| J & H Medical Ltd | Health & social care | 2020 |
| J & R Friend Property Ltd | Real estate | 2022 |
| J & W Estates Limited | Real estate | 2024 |
| J B 13 Limited | Financial services | 2011 |
| J B J Construction Limited | Construction | 2004 |
| J Booth Catering Limited | Hospitality | 2018 |
| J G P Properties (Holdings) Limited | Financial services | 2018 |
| J G P Properties Ltd | Real estate | 1994 |
| J Haywood Farms Limited | Agriculture & fishing | 2000 |
| J J Cook Farm Machinery Limited | Wholesale & retail | 2012 |
| J J Hilton Developments Limited | Hospitality | 2020 |
| J Kerr Floors Limited | Construction | 2000 |
| J N F Roofing and Building Ltd | Construction | 2017 |
| J Wilson Construction Ltd | Construction | 2022 |
| J Wilson Lawns & Fencing Ltd | Administrative & support | 2023 |
| J&H Publishing Limited | Information & communication | 2025 |
| J&K Systems PVT Ltd | Information & communication | 2023 |
| J&M Property Solutions Ltd | Real estate | 2018 |
| J. F. Brown Ltd | Other services | 2013 |
| J.C Bibby Steel Erecting Ltd | Construction | 2020 |
| J.E.Glover Limited | Professional & scientific | 1952 |
| J.Hides Trading Ltd | Wholesale & retail | 2022 |
| J.M. Controls Limited | Information & communication | 1997 |
| J.P-P. Sparx Ltd | Manufacturing | 2019 |
| J.R. Clark Limited | Agriculture & fishing | 1981 |
| JA Land Ltd | Real estate | 2025 |
| JA Rooms Ltd | Real estate | 2017 |
| Jabbla UK Limited | Wholesale & retail | 2007 |
| Jack Harris (Grantham) Ltd. | Manufacturing | 2015 |
| Jack Warren Ltd | Other services | 2020 |
| Jackson JMR Limited | Professional & scientific | 2011 |
| Jackson Stops & Staff Limited | Real estate | 2019 |
| Jackson-Stops Limited | Real estate | 2017 |
| Jaco HMO Solutions Ltd | Real estate | 2025 |
| Jaks Casulas Ltd | Wholesale & retail | 2017 |
| Jalan END Limited | Hospitality | 2025 |
| JAM (Capital) Holdings Ltd | Financial services | 2016 |
| JAM (JEZ Allman Mentoring) Ltd | Wholesale & retail | 2024 |
| Jamanda Capital Limited | Financial services | 2016 |
| Jamanda Limited | Financial services | 2016 |
| Jamara FNF Limited | Hospitality | 2025 |
| James Avery Eventing Limited | Arts & recreation | 2015 |
| James Shaw Group Ltd | Financial services | 2025 |
| Jamesgrangerdesign Ltd | Professional & scientific | 2021 |
| Jamie Holt Bricklaying & Building Ltd | Construction | 2021 |
| Jandal Investments Limited | Financial services | 1956 |
| Jasinski Farms Limited | Agriculture & fishing | 2022 |
| Jason Wilson-Law Ltd | Construction | 2004 |
| Jaxon Limited | Wholesale & retail | 2009 |
| Jaya SAI Limited | Wholesale & retail | 2018 |
| Jaylew (Engineering) Limited | Manufacturing | 1970 |
| Jaylew ARC Ltd | Manufacturing | 2023 |
| Jaylew Group Limited | Professional & scientific | 2026 |
| JAZ Facilities Management Ltd | Construction | 2025 |
| JAZ Mini Market Grantham Limited | Wholesale & retail | 2025 |
| JC Mellor Associates Limited | Professional & scientific | 2021 |
| JCA Consultancy Ltd | Professional & scientific | 2024 |
| JCC Farms Limited | Agriculture & fishing | 2020 |
| JD Power Solutions Ltd | Construction | 2025 |
| JDM Parts Ltd | Wholesale & retail | 2024 |
| JE & SON Removals Ltd | Transport & logistics | 2025 |
| Jellyfish Hospitality Limited | Professional & scientific | 2025 |
| Jemoda Heart Care Ltd | Health & social care | 2016 |
| Jenkinson Intelligence Consultancy Ltd | Public administration | 2025 |
| Jenkyn LLP | | 2007 |
| Jessica PVT Ltd | Hospitality | 2026 |
| JF Heating and Plumbing Ltd | Construction | 2016 |
| Jfisk Ltd | Manufacturing | 2021 |
| JG Partnership Investments Ltd | Real estate | 2023 |
| JG Property Group Ltd | Real estate | 2022 |
| JG Property Solutions Ltd | Real estate | 2018 |
| JGM Transport Ltd | Transport & logistics | 2025 |
| Jgpi Ltd | Information & communication | 2016 |
| JH Software Ltd | Information & communication | 2019 |
| JHP Consultancy Services Ltd | Professional & scientific | 2024 |
| JIG U.K. Ltd | Wholesale & retail | 1993 |
| Jimmy Dale Leadership Ltd | Professional & scientific | 2025 |
| JJ Property Group Ltd | Households | 2019 |
| JJ Soft Tissue Limited | Health & social care | 2025 |
| JL Quantity Surveying Limited | Professional & scientific | 2023 |
| JM Construction and Haulage Ltd | Construction | 2023 |
| JM Partnership Investments Ltd | Real estate | 2023 |
| JM Partnership Properties Ltd | Real estate | 2024 |
| JMR Music Services Ltd | Professional & scientific | 2018 |
| Jmss Financial Limited | Professional & scientific | 2024 |
| JND Aviation International Ltd | Professional & scientific | 2022 |
| JNF Roofing Ltd | Construction | 2013 |
| Joah Jackets Ltd | Wholesale & retail | 2023 |
| Jobuxtonconsulting Ltd | Professional & scientific | 2019 |
| Jodaq Foods Ltd | Hospitality | 2024 |
| Jodaq Technology Ltd | Information & communication | 2018 |
| John Coverdale LLP | | 2006 |
| John Loosemore Glazing Limited | Construction | 2003 |
| John Oldrid Partnership Trust Limited | Other services | 1995 |
| JON Senescall Consultancy Limited | Wholesale & retail | 2018 |
| Joseph Medical Ltd | Health & social care | 2020 |
| Joseth Foods Limited | Hospitality | 2021 |