| J & C Blackman Limited | Professional & scientific | 2019 |
| J & Co. Group Ltd | Financial services | 2022 |
| J & E Property Network Services Ltd | Real estate | 2025 |
| J & I Singh Ltd | Wholesale & retail | 2017 |
| J & K Commerce Limited | Real estate | 2025 |
| J & K Investments & Developments Limited | Real estate | 2021 |
| J & L Construction Services Ltd | Construction | 2018 |
| J & M Care Limited | Health & social care | 2002 |
| J & N Holdings Limited | Administrative & support | 2007 |
| J & N Property Developments Limited | Construction | 2018 |
| J & S Cars Limited | Wholesale & retail | 2005 |
| J & S Health and Wellness Ltd | Health & social care | 2025 |
| J & S Palmer Limited | Real estate | 2020 |
| J & S Potatoes Limited | Wholesale & retail | 2021 |
| J & Sons Logistics Ltd | Transport & logistics | 2022 |
| J and M Homes Limited | Financial services | 2023 |
| J Butler Consulting Ltd | Wholesale & retail | 2023 |
| J C Security UK Limited | Other services | 2015 |
| J Carmichael Orthopaedics Ltd | Health & social care | 2012 |
| J F Halliday Limited | Transport & logistics | 2014 |
| J Gregory Property Investments Ltd | Construction | 2019 |
| J Howe Landscaping Ltd | Construction | 2017 |
| J J Construction (NW) Ltd | Construction | 2013 |
| J Johnson's Brickwork Ltd | Construction | 2022 |
| J L 2025 Limited | Other services | 2015 |
| J Marsh Holdings Limited | Administrative & support | 2023 |
| J Neville Opticians Limited | Wholesale & retail | 2005 |
| J O Moore Limited | Administrative & support | 2025 |
| J P Hefferon Ltd | Construction | 2019 |
| J Perkins Holdings Limited | Financial services | 2024 |
| J Polson Construction Limited | Construction | 2022 |
| J R Atkins Consultancy Limited | Information & communication | 2016 |
| J S Davidson Holdings Ltd | Transport & logistics | 2018 |
| J S Davidson Ltd | Manufacturing | 1995 |
| J Scriven Consultancy Ltd | Administrative & support | 2022 |
| J Steels Services Limited | Wholesale & retail | 2019 |
| J Turner Brickwork & Building Services Ltd | Construction | 2023 |
| J V Plastering Services Limited | Construction | 2022 |
| J W Developments (Peterborough) Limited | Construction | 2003 |
| J Watson Scaffolding Ltd | Extraterritorial | 2024 |
| J&D Beauty Limited | Wholesale & retail | 2014 |
| J&E Francis Holdings Limited | Financial services | 2025 |
| J&J Global Services Ltd | Real estate | 2024 |
| J&J Houselet Limited | Professional & scientific | 1997 |
| J&M Healthcare Limited | Health & social care | 2019 |
| J&W HGV Services Ltd | Transport & logistics | 2018 |
| J'Ai Bonne Esperance Limited | Financial services | 2018 |
| J'Re Hair Limited | Other services | 2003 |
| J, R G & S Mould Limited | Wholesale & retail | 2012 |
| J-A Properties & Development Ltd | Households | 2022 |
| J. & S. Properties Limited | Real estate | 1987 |
| J. Ansong Medical Ltd | Health & social care | 2019 |
| J. E. Coakley Limited | Wholesale & retail | 2005 |
| J. Moriarty Limited | Construction | 2006 |
| J.& L.K.Braybrooks Limited | Agriculture & fishing | 1949 |
| J.A.B.V. Ltd | Transport & logistics | 2024 |
| J.A.Hutchinson(Wansford)Limited | Transport & logistics | 1965 |
| J.A.T Ltd | Transport & logistics | 2016 |
| J.Chapman & Co Ltd | Information & communication | 2022 |
| J.Dan.M. Ltd | Transport & logistics | 2018 |
| J.E. & V.M. Dalton Limited | Manufacturing | 1952 |
| J.Evans Construction Ltd | Construction | 2022 |
| J.J Garden & Tree Care Ltd | Administrative & support | 2025 |
| J.Jamie Photography Ltd | Professional & scientific | 2017 |
| J.S.R. (Investments) Limited | Real estate | 1961 |
| J.Slice Plastering Ltd | Construction | 2022 |
| J.W. Page Holdings Limited | Financial services | 2026 |
| J.W.E.Banks,Limited | Agriculture & fishing | 1951 |
| J.Wesolowski Ltd | Transport & logistics | 2013 |
| J1 Group Limited | Financial services | 2021 |
| J1 Property Ltd | Real estate | 2024 |
| J1 Technology Limited | Information & communication | 2021 |
| J2 Construction Limited | Construction | 2017 |
| J2 Lettings Limited | Real estate | 2020 |
| J3 & Kids Limited | Administrative & support | 2015 |
| J99 Limited | Professional & scientific | 2017 |
| JA Vehicle Solutions Ltd | Wholesale & retail | 2026 |
| JA Ventrues Ltd | Wholesale & retail | 2026 |
| Ja-Kar Transport Ltd | Transport & logistics | 2025 |
| JA90 Holdings Ltd | Financial services | 2022 |
| JAB Recycling Ltd | Water & waste | 2024 |
| Jabbasport Limited | Wholesale & retail | 2002 |
| Jabberwocky Investments Limited | Professional & scientific | 2017 |
| JAC Publications Limited | Professional & scientific | 2010 |
| Jacarto Ltd | Real estate | 2026 |
| Jace Reese Limited | Households | 2025 |
| Jack & Grace Limited | Professional & scientific | 2020 |
| Jack Bowers Education Ltd | Education | 2018 |
| Jack Byron Electrical Ltd | Construction | 2018 |
| Jack Pamula Ltd | Transport & logistics | 2015 |
| Jack Simons Limited | Administrative & support | 2004 |
| Jack Spedition Ltd | Transport & logistics | 2026 |
| Jack Transport 511 Ltd | Transport & logistics | 2024 |
| Jackdaw Domestic Buildings Ltd | Construction | 2022 |
| Jacklin Jeffs Limited | Real estate | 2018 |
| Jackunas Limited | Extraterritorial | 2013 |
| Jacob Barber Ltd | Other services | 2025 |
| Jacob Well Ltd. | Professional & scientific | 2012 |
| Jacques-Joe Limited | Manufacturing | 2017 |
| Jacqui Barnett Limited | Education | 2026 |