| Jamsmd UK Limited | Wholesale & retail | 2025 |
| Jamuke Incorporated Limited | Information & communication | 2017 |
| Jamvan Conversions Limited | Manufacturing | 2021 |
| Jamyra Limited | Real estate | 2026 |
| JAN a Associates Ltd | Health & social care | 2020 |
| Janab Limited | Real estate | 2023 |
| Janahan Ltd | Arts & recreation | 2015 |
| Janan Surgical Care Limited | Health & social care | 2019 |
| Jane Dormer at 26A Ltd | Real estate | 2021 |
| Jane Medical 2024 Limited | Health & social care | 2024 |
| Janesis Immense Care Ltd | Health & social care | 2023 |
| Jangregor Limited | Transport & logistics | 2015 |
| Jangregor Properties Limited | Real estate | 2026 |
| Jankos Trans Ltd | Transport & logistics | 2017 |
| Jannan Ltd | Health & social care | 2021 |
| JANNAT24 Ltd | Wholesale & retail | 2024 |
| Janoct Consultancy UK Ltd | Information & communication | 2009 |
| Janson Group Ltd | Real estate | 2015 |
| Janus Capital Holdings Ltd | Financial services | 2019 |
| Janus Media UK Ltd | Information & communication | 2017 |
| Janus Safety Solutions Ltd. | Manufacturing | 2005 |
| Janvaroz Ltd | Health & social care | 2018 |
| JAP Motorcycles Limited | Wholesale & retail | 2025 |
| Japan Import MK Limited | Wholesale & retail | 2023 |
| Japan Kemitech Ltd | Manufacturing | 2025 |
| Japan Station Limited | Wholesale & retail | 2025 |
| Jara Holdings Limited | Financial services | 2020 |
| Jara Property Limited | Real estate | 2024 |
| Jarana Ltd | Real estate | 2021 |
| Jaranda Ltd | Health & social care | 2017 |
| Jardinade Limited | Real estate | 1988 |
| Jardines (U.K.) Limited | Wholesale & retail | 1984 |
| Jardines Developments Limited | Construction | 2016 |
| Jardines Ltd | Wholesale & retail | 2006 |
| Jardines Property Developments Limited | Construction | 2012 |
| Jared Sheridan Ventures Limited | Professional & scientific | 2024 |
| Jari Solutions Ltd | Professional & scientific | 2018 |
| Jarri Limited | Health & social care | 2013 |
| Jars Inc Ltd | Wholesale & retail | 2020 |
| Jarvis (Great Chilmington) Limited | Construction | 2017 |
| Jarvis Products UK Ltd. | Professional & scientific | 2018 |
| Jaskprop Ltd | Real estate | 2020 |
| Jasmine Business Solutions Ltd | Hospitality | 2022 |
| Jasno Ltd | Information & communication | 2026 |
| Jason Brogden Consulting Limited | Professional & scientific | 2014 |
| Jaspar Property Solutions Ltd | Construction | 2026 |
| Jaspers Pizzeria Ltd | Hospitality | 2023 |
| Jastra Empire Ltd | Wholesale & retail | 2025 |
| JAT Creative Ltd | Wholesale & retail | 2025 |
| Jaunius Petkunas Construction Ltd | Construction | 2018 |
| Java Facilities Limited | Professional & scientific | 2011 |
| Jaxon Finley Property Ltd | Real estate | 2025 |
| JAY & M Medicals Ltd | Health & social care | 2023 |
| JAY Force Limited | Professional & scientific | 2008 |
| JAY Nels Logistics Limited | Transport & logistics | 2024 |
| Jaya Mistry & Co Limited | Manufacturing | 2020 |
| Jayanth VC Limited | Financial services | 2018 |
| Jaybee Leasing Limited | Real estate | 1997 |
| Jayjaytrans Ltd | Transport & logistics | 2024 |
| Jayjs Food Ltd | Hospitality | 2022 |
| Jayken Enterprises Ltd | Wholesale & retail | 2015 |
| Jaylux Ltd | Wholesale & retail | 2025 |
| Jayne Devlin Consulting Limited | Hospitality | 2010 |
| Jayni Properties Limited | Real estate | 2022 |
| Jayper Ltd | Wholesale & retail | 2022 |
| Jays Heating and Plumbing Company Limited | Construction | 1970 |
| Jays Quick FIX Limited | Other services | 2025 |
| Jayson Associates Ltd | Real estate | 2025 |
| Jaytvmedia Ltd | Professional & scientific | 2020 |
| JAZ Property Investments Limited | Real estate | 2021 |
| Jazah International Ltd | Information & communication | 2010 |
| Jazar Ltd | Real estate | 2002 |
| Jazzed UP Hairdressing Ltd | Other services | 2024 |
| Jazzys Restaurant Limited | Hospitality | 2013 |
| JB Assistant Solutions Ltd | Other services | 2024 |
| JB BJ Ltd | Wholesale & retail | 2020 |
| JB Carpentry & Maintenance Ltd | Construction | 2023 |
| JB Commerce Ltd | Wholesale & retail | 2014 |
| JB Impact Ltd | Professional & scientific | 2023 |
| JB Protection Ltd | Financial services | 2021 |
| Jb&Thl Consultancy Limited | Wholesale & retail | 2023 |
| Jb-Av Limited | Information & communication | 2008 |
| JBA Professional Services Ltd | Information & communication | 2022 |
| Jbbagstore Ltd | Manufacturing | 2025 |
| JBK Corporate Advisory Limited | Professional & scientific | 2011 |
| JBS Homes Ltd | Households | 2019 |
| JBWG11 Ltd | Information & communication | 2011 |
| JBWG12 Limited | Real estate | 2015 |
| JC Executive Chauffeur Ltd | Transport & logistics | 2026 |
| JC Greenaway Limited | Administrative & support | 2025 |
| JC Heating and Electrical Limited | Construction | 2017 |
| JC Management and Training Ltd | Construction | 2026 |
| JCA Developments Limited | Real estate | 2020 |
| JCA Distributions Ltd | Wholesale & retail | 2026 |
| Jcal Property Investments Ltd | Real estate | 2026 |
| JCB GAS Heating Services Ltd. | Energy | 2014 |
| JCC Automotive Ltd | Wholesale & retail | 2024 |
| JCD Estates Limited | Real estate | 2015 |
| JCD Limited | Professional & scientific | 2010 |
| JCD Professional Services Ltd | Professional & scientific | 2015 |