| Jackson & Chin Properties Ltd | Real estate | 2024 |
| Jackson Hill Ltd | Professional & scientific | 2020 |
| Jackson Pelling Ltd | Professional & scientific | 2021 |
| Jackson Steward Ltd | Wholesale & retail | 2021 |
| Jaffa Kitchens Limited | Manufacturing | 2024 |
| Jagma Property Services Limited | Construction | 2019 |
| Jags Medical Services Ltd | Health & social care | 2013 |
| Jaiistyleit Hair & Beauty Salon Ltd | Other services | 2025 |
| JAJ Properties Management Limited | Financial services | 2024 |
| JAJ Real Estate Ltd | Real estate | 2026 |
| Jaja Associates Ltd | Construction | 2022 |
| JAK Capital Limited | Households | 2005 |
| JAK Consultancy Ltd | Administrative & support | 2014 |
| Jakars Ltd | Real estate | 2025 |
| Jakarta Enterprises Limited | Wholesale & retail | 2020 |
| Jake Kelly Ltd | Construction | 2019 |
| JAM Central Management Company Limited | Real estate | 2012 |
| JAM Junction Ltd | Wholesale & retail | 2018 |
| JAM Music Limited | Arts & recreation | 2016 |
| Jama (BD) Ltd | Health & social care | 2020 |
| Jamaica Gate Ltd | Hospitality | 2026 |
| James a Newman Limited | Administrative & support | 2012 |
| James Art Gallery Ltd | Wholesale & retail | 2021 |
| James Charlotte (2008) Limited | Extraterritorial | 2008 |
| James Fast Plumber Ltd | Construction | 2024 |
| James Gorst Architects Limited | Professional & scientific | 2002 |
| James Gorst Associates Limited | Professional & scientific | 2015 |
| James Grubb Ltd | Professional & scientific | 2019 |
| James Kids Home Ltd | Health & social care | 2018 |
| James Marketing & Design Limited | Administrative & support | 2006 |
| James Sanderson Limited | Health & social care | 2010 |
| James Travel Ltd | Transport & logistics | 2020 |
| Jamhat Limited | Real estate | 2022 |
| Jamisphere Limited | Professional & scientific | 2025 |
| Jane, Saunders & Manning Master Shoemakers Limited | Wholesale & retail | 2026 |
| Janine Clayton Design Limited | Professional & scientific | 2026 |
| JAR and Fern Limited | Professional & scientific | 2016 |
| JAR Homes & Properties Ltd | Real estate | 2022 |
| Jardin Hospitality Group Limited | Hospitality | 2024 |
| Jarga Sushi Wembley Ltd | Manufacturing | 2025 |
| Jarvis Studios Limited | Real estate | 2016 |
| Jason (Coffee Blends) Limited | Real estate | 1958 |
| Jasser Ltd | Professional & scientific | 2023 |
| Javv Healthcare Ltd | Health & social care | 2017 |
| Javvnests Ltd | Real estate | 2023 |
| JAW London Ltd | Manufacturing | 2022 |
| Jawa Group Ltd | Extraterritorial | 2007 |
| JAY SAI Godavari Group Ltd | Professional & scientific | 2024 |
| Jayawo Limited Limited | Health & social care | 2025 |
| Jaybec Global Limited | Professional & scientific | 2016 |
| Jayford Flat Management Company Limited | Households | 1991 |
| Jayhern Engineering Limited | Manufacturing | 1971 |
| Jayhern Holdings Limited | Real estate | 2021 |
| Jayscustomlab Ltd | Wholesale & retail | 2025 |
| Jazz Wynter Limited | Health & social care | 2022 |
| JB Accounting Solutions Ltd | Administrative & support | 2017 |
| JB Building & Plumbing Services Ltd | Construction | 2025 |
| JB Good Roofing Limited | Construction | 2015 |
| JBF Investments Limited | Other services | 2016 |
| JBJ Group Ltd | Real estate | 2023 |
| JC Managing Agents Limited | Real estate | 2004 |
| Jc-Lovann Ltd | Health & social care | 2023 |
| JCA Claims Consultancy Limited | Administrative & support | 2018 |
| JCK Healthcare Services Ltd | Health & social care | 2019 |
| Jclutterbuck IT Limited | Information & communication | 2012 |
| JCM Care Experts Limited | Health & social care | 2013 |
| JD & JJ Stella Maris Limited | Public administration | 2022 |
| JD Drylining & Ceilings Ltd | Construction | 2025 |
| JD Life Coach Services Ltd | Information & communication | 2023 |
| JD Plumbum Ltd | Construction | 2025 |
| JD Smart Building Services Ltd | Construction | 2025 |
| Jdev Consulting Ltd | Information & communication | 2019 |
| JDL Premises Limited | Real estate | 2025 |
| JDS Building Consultancy Ltd | Professional & scientific | 2020 |
| JDS Cricket Coaching Limited | Arts & recreation | 2023 |
| JDW Advisory Limited | Professional & scientific | 2019 |
| Jeal Flowers Limited | Wholesale & retail | 1989 |
| Jefferys Consulting and Innovation Enterprises Limited | Professional & scientific | 2015 |
| Jegom Services Limited | Wholesale & retail | 2024 |
| Jehan Cyber Force Ltd | Information & communication | 2018 |
| Jehan Group Ltd | Financial services | 2019 |
| Jeko Events Ltd | Arts & recreation | 2023 |
| Jemcrest Limited | Households | 1998 |
| Jenic & Co Limited | Financial services | 2012 |
| Jenit Limited | Information & communication | 2021 |
| Jensar Ltd | Health & social care | 2015 |
| Jensprima Instruments Limited | Manufacturing | 2017 |
| Jeps Home Solutions Ltd | Construction | 2025 |
| Jeremy Ellis Limited | Professional & scientific | 2020 |
| Jeremy Lawrence Limited | Financial services | 2004 |
| Jerk & Bird Ltd | Hospitality | 2019 |
| Jermis World Ltd | Health & social care | 2020 |
| Jerry Yachting Ltd | Extraterritorial | 2025 |
| Jesse James Agency Ltd. | Arts & recreation | 2021 |
| Jessica House RTM Company Limited | Households | 2025 |
| Jester Farm Services Limited | Agriculture & fishing | 2002 |
| JET SET ET Limited | Households | 2001 |
| Jethwa Limited | Real estate | 1981 |
| Jetnor Ltd | Information & communication | 2023 |
| Jetpos Consulting Service Limited | Extraterritorial | 2019 |