| J Rosenblatt LLP | | 2011 |
| J Sell Healthcare Ltd | Health & social care | 2025 |
| J Swindlehurst Limited | Professional & scientific | 2025 |
| J Towler Limited | Administrative & support | 2016 |
| J W Miller Consultancy Ltd | Administrative & support | 2023 |
| J Wilton Ltd | Real estate | 2019 |
| J&C MCR Limited | Professional & scientific | 2024 |
| J&M Brothers Investments Limited | Real estate | 2026 |
| J. & Nettaroon Limited | Administrative & support | 2020 |
| J. Davidson (Car Sales) Limited | Water & waste | 1980 |
| J. Davidson (Management) Limited | Professional & scientific | 2024 |
| J. Davidson (Properties) Limited | Real estate | 2011 |
| J. Davidson Scrap Metal Processors (Northwich) Limited | Water & waste | 2024 |
| J. Davidson Scrap Metal Processors Limited | Water & waste | 2011 |
| J. Whelan Contracts Limited | Wholesale & retail | 2017 |
| J.A. Harvey (Bassingham) Limited | Manufacturing | 1973 |
| J.A. Payne Limited | Construction | 1963 |
| J.Allcock & Sons Limited | Manufacturing | 1928 |
| J.And N.Dawson Limited | Real estate | 1946 |
| J.B.S. Consultancy Ltd | Information & communication | 2022 |
| J.D.C Holdco Limited | Financial services | 2023 |
| J.D.F. Interim Solutions Limited | Administrative & support | 2011 |
| J.Davidson (Holdings) Limited | Wholesale & retail | 2011 |
| J.F. Hardy Limited | Professional & scientific | 2007 |
| J.Fisher Ltd | Wholesale & retail | 2023 |
| J3KIM Holdings Limited | Financial services | 2024 |
| JA Harvey (Bassingham) Group Finance Limited | Financial services | 2024 |
| JA Harvey (Bassingham) Holdings Limited | Financial services | 2024 |
| Jack Shaw Contractors Limited | Construction | 1996 |
| Jackie Harrop Limited | Administrative & support | 2009 |
| Jackscottage Limited | Administrative & support | 2000 |
| Jacksons Foods Limited | Wholesale & retail | 2023 |
| Jacob Carter Ltd | Administrative & support | 2017 |
| Jacobel Limited | Financial services | 2024 |
| JACOBS33 Limited | Public administration | 2020 |
| Jacqueline Cripps Limited | Professional & scientific | 2019 |
| Jada Consulting Services Limited | Professional & scientific | 2022 |
| Jada News Ltd | Wholesale & retail | 2014 |
| Jadan Properties Ltd | Real estate | 2020 |
| Jade Anna Yoga Limited | Health & social care | 2024 |
| Jade FOX Properties Ltd | Real estate | 2021 |
| Jadestream Analytics Limited | Administrative & support | 2024 |
| Jahjah Power Solutions Ltd | Manufacturing | 2025 |
| Jahnavi Properties Limited | Real estate | 2021 |
| Jaina Fashion Limited | Wholesale & retail | 2019 |
| JAK Steel & Supplies Limited | Construction | 2015 |
| JAK Steel Group Limited | Financial services | 2021 |
| Jake Taylor Fitness Ltd | Arts & recreation | 2021 |
| Jakes ALE House Limited | Administrative & support | 2016 |
| Jalisrubo Limited | Real estate | 2025 |
| Jamaica Street Ltd | Real estate | 2013 |
| James Bennett (Quarries) Limited | Real estate | 1940 |
| James Blackburn (Manchester) Limited | Wholesale & retail | 1970 |
| James Bridge Limited | Real estate | 1996 |
| James Burke Limited | Agriculture & fishing | 2016 |
| James Doodson Carpets & Flooring Ltd | Construction | 2015 |
| James Maguire & Co Limited | Professional & scientific | 2011 |
| James Oldfield Limited | Other services | 1984 |
| James Property Group Limited | Real estate | 2019 |
| James Smith Health Consultancy Limited | Information & communication | 2018 |
| JAMES2 Developments Limited | Construction | 2025 |
| Jamroo Limited | Information & communication | 2022 |
| JAN Pharmaceutical Limited | Wholesale & retail | 2024 |
| Jane Halliday Neurosurgeon Limited | Health & social care | 2024 |
| Jane Porter Limited | Professional & scientific | 2025 |
| Janellie Ltd | Real estate | 2021 |
| Janet Meehan and Partners Limited | Health & social care | 2003 |
| Janjua Aviation Limited | Professional & scientific | 2026 |
| Janson Holdings Limited | Administrative & support | 2018 |
| Janus J&C Trading Limited | Wholesale & retail | 2023 |
| Janus Private Clients Limited | Construction | 2019 |
| Janven Limited | Extraterritorial | 2014 |
| Japan Premium UK Limited | Hospitality | 2022 |
| JAR Analytical Solutions Limited | Administrative & support | 2024 |
| Jardim Grill Ltd | Hospitality | 2021 |
| Jarkm Ltd | Health & social care | 2019 |
| Jarvis Property Group Limited | Real estate | 2019 |
| Jasda Property Holdings Ltd | Real estate | 2021 |
| Jasper Security Limited | Professional & scientific | 2025 |
| JAY and Ava’S Kitchen Limited | Hospitality | 2025 |
| Jayaguru Consultancy Limited | Administrative & support | 2012 |
| Jayawa Limited | Households | 1985 |
| Jayden Paradise Limited | Hospitality | 2026 |
| Jayfour Services Limited | Administrative & support | 2025 |
| Jaymeni Patel Design Limited | Construction | 2014 |
| JB Building Management Limited | Construction | 2025 |
| JB Business Advisory Limited | Administrative & support | 2015 |
| JB GAS & Plumbing Ltd | Construction | 2021 |
| JB HR Ltd | Administrative & support | 2006 |
| JB Pics Limited | Real estate | 2017 |
| JB Property and Investments Limited | Real estate | 2023 |
| JBJ Lettings Ltd | Real estate | 2020 |
| JC Drye Limited | Professional & scientific | 2025 |
| JC Tree Services Limited | Administrative & support | 2023 |
| JCH Asset MGT Ltd | Real estate | 2020 |
| JCJ Capital Limited | Real estate | 2020 |
| JCK Management Services Ltd | Professional & scientific | 2024 |
| JCP Limited | Professional & scientific | 2023 |
| JD Ehealth Consulting Limited | Professional & scientific | 2018 |
| JD Locations Limited | Information & communication | 2016 |