| J.Lechowicz Transport Ltd. | Wholesale & retail | 2016 |
| J.Leyden Joinery Ltd | Manufacturing | 2025 |
| J.M Invest Ltd | Real estate | 2025 |
| J.M.D. Haulage Contractors Limited | Transport & logistics | 1978 |
| J.M.D. Haulage Group Limited | Financial services | 2023 |
| J.M.V. Property Limited | Real estate | 2001 |
| J.O. Property Group Ltd | Real estate | 2020 |
| J.Osman Farah-Neurosurgery Limited | Health & social care | 2021 |
| J.P. Tisdale (Demolition) Limited | Construction | 1990 |
| J.P.Hart Limited | Financial services | 2013 |
| J.P.N. Validation Consultancy Ltd | Professional & scientific | 2021 |
| J.Piatak Trans Ltd | Transport & logistics | 2018 |
| J.R Trans Ltd | Transport & logistics | 2025 |
| J.R.S Render & Plastering Solutions Ltd | Water & waste | 2025 |
| J.R.W Validation & Compliance Limited | Professional & scientific | 2018 |
| J.Riley Roofing & Building Services Ltd | Construction | 2020 |
| J.S Accommodation Services Limited | Real estate | 2015 |
| J.Somers Real Estate Limited | Real estate | 2025 |
| J.T.S Cleaning Ltd | Administrative & support | 2020 |
| J.W. Monks Limited | Administrative & support | 2008 |
| J.W.James & Co.(Salisbury Farm Dairies)Limited | Wholesale & retail | 1964 |
| J1 Electrical Limited | Construction | 2011 |
| J1 Electrics Limited | Administrative & support | 2015 |
| J16MUL Ltd | Construction | 2024 |
| J26 Productions Ltd | Information & communication | 2023 |
| J2N2 Capital Ltd | Construction | 2024 |
| J2N2 Holdings Ltd | Construction | 2022 |
| J2N2 Promotions Ltd | Professional & scientific | 2024 |
| J3-UK Engineering Ltd | Construction | 2019 |
| J4M Perfect Source Ltd | Wholesale & retail | 2026 |
| J52 Engineering Ltd | Professional & scientific | 2026 |
| J8 Capital Ltd | Professional & scientific | 2020 |
| J96 Group Ltd | Transport & logistics | 2025 |
| J@M Consultants Limited | Information & communication | 2013 |
| JA Aesthetics Ltd | Other services | 2025 |
| JA Groundworks Northwest Limited | Construction | 2025 |
| JA Properties NW Limited | Real estate | 2023 |
| Jabak Security Ltd | Administrative & support | 2018 |
| Jabosa International Ltd | Real estate | 2019 |
| JAC MAC Properties Ltd | Real estate | 2021 |
| JAC Plastering and Rendering Ltd | Construction | 2026 |
| Jacdomat Limited | Health & social care | 2019 |
| Jacek Stodolny Transport Ltd. | Transport & logistics | 2016 |
| Jaceyland Limited | Real estate | 2021 |
| Jack Bannon Support Services Ltd. | Health & social care | 2018 |
| Jack Edwards Coaching Ltd | Arts & recreation | 2021 |
| Jack GK Ltd | Information & communication | 2025 |
| Jack Hodson Limited | Wholesale & retail | 1966 |
| Jack J Murphy Care Limited | Health & social care | 2023 |
| Jack James Property Ltd | Real estate | 2022 |
| Jack Jones Trust | Information & communication | 2012 |
| Jack's Care Limited | Health & social care | 2025 |
| Jackalnel Limited | Administrative & support | 2017 |
| Jackalope Games Ltd | Information & communication | 2025 |
| Jackarhys Ltd | Other services | 2025 |
| Jackbo Enterprises Limited | Real estate | 2015 |
| Jackets Baked Potatoes Limited | Hospitality | 2005 |
| Jackhousemarketing Limited | Wholesale & retail | 2026 |
| Jackie and Michael Limited | Health & social care | 2024 |
| Jackie Fairweather Ltd | Health & social care | 2026 |
| Jackie Fisher Limited | Professional & scientific | 2021 |
| Jackie Food Service Ltd | Hospitality | 2025 |
| Jacko's Tyres & MOT Ltd | Wholesale & retail | 2024 |
| Jackofalltradesbusiness Ltd | Construction | 2021 |
| JACKOS4COMPANIES Ltd | Wholesale & retail | 2025 |
| Jackpotcomps Ltd | Arts & recreation | 2026 |
| Jackrm Ltd | Information & communication | 2026 |
| Jacksadlerentertainment Ltd | Arts & recreation | 2025 |
| Jackson Estates Ltd | Real estate | 2021 |
| Jackson Lees Group Ltd | Professional & scientific | 2011 |
| Jackson Lees Trust Corporation Limited | Administrative & support | 2019 |
| Jackson Lewis Limited | Other services | 2018 |
| Jackson Neuro Physio and Rehabilitation Ltd | Health & social care | 2020 |
| Jackson Rachel Louise Ltd | Wholesale & retail | 2026 |
| Jackson Statistical Analysis and Consultancy Ltd | Professional & scientific | 2018 |
| Jackson-Kelly Ltd | Agriculture & fishing | 2024 |
| Jacksonvilla Investments (Liverpool) Limited | Real estate | 1962 |
| Jackson’S Retail Ltd | Wholesale & retail | 2024 |
| Jackster Trading Ltd | Wholesale & retail | 2015 |
| Jacl Holdings Ltd | Other services | 2022 |
| Jacob&Jude Property Solution Ltd | Real estate | 2015 |
| Jacobcorscoaching Ltd | Arts & recreation | 2026 |
| Jacobjude Limited | Real estate | 2014 |
| Jacobsen Analytics Limited | Professional & scientific | 1988 |
| Jacoob Ltd | Administrative & support | 2022 |
| Jacqueline Court Limited | Real estate | 2007 |
| Jacqueline Kirkham Studios Limited | Extraterritorial | 2004 |
| Jacqueline Rafferty Consulting Ltd | Administrative & support | 2024 |
| Jacqui Techeras Ltd | Health & social care | 2014 |
| Jacqui Vale Designs Limited | Wholesale & retail | 2016 |
| Jacy Marketing Ltd | Professional & scientific | 2025 |
| JAD Holdings Limited | Wholesale & retail | 2026 |
| JAD Rail Services Ltd | Construction | 2009 |
| Jadbennett Ltd | Professional & scientific | 2025 |
| Jade Alliance Ltd | Transport & logistics | 2021 |
| Jade Fashion Ltd | Wholesale & retail | 2024 |
| Jade View Yummy YUM Ltd | Hospitality | 2022 |
| Jadel Cleaning Company Ltd | Administrative & support | 2026 |
| Jadency Ltd | Administrative & support | 2025 |
| Jader Property Ltd | Real estate | 2017 |