| Janros Care Services Limited | Health & social care | 2022 |
| Jans Haulage Limited | Transport & logistics | 2010 |
| Jans Housing Ltd | Real estate | 2026 |
| Janson International Limited | Wholesale & retail | 2018 |
| Jansons Worldwide Limited | Wholesale & retail | 2020 |
| Jantor Limited | Real estate | 2020 |
| January Thirteen Limited | Administrative & support | 2018 |
| Janus Point Limited | Financial services | 2026 |
| Januviththa Ltd | Real estate | 2020 |
| Janzeb Group Limited | Other services | 2023 |
| JAP Car Breakers Limited | Wholesale & retail | 2010 |
| JAP Hybrid Cars Ltd | Wholesale & retail | 2023 |
| JAP Keshav Properties Ltd | Households | 2025 |
| JAP Machinery Limited | Wholesale & retail | 2012 |
| JAP Motor Imports UK Ltd | Wholesale & retail | 2023 |
| JAP Transport Ltd | Transport & logistics | 2026 |
| Japa International Ltd | Wholesale & retail | 2015 |
| Japan Auto Sales Ltd | Wholesale & retail | 2022 |
| Japan Autos Ltd | Wholesale & retail | 2019 |
| Japan Cars Parts Ltd | Wholesale & retail | 2024 |
| Japan Experience and Goods Limited | Wholesale & retail | 2024 |
| Japan Imports Ltd | Wholesale & retail | 2023 |
| Japan Motor Limited | Wholesale & retail | 2025 |
| Japan Traders Ltd | Wholesale & retail | 2023 |
| Japanese Accessories & German Car Solutions Ltd | Wholesale & retail | 2014 |
| Japanese Imported Vehicles Ltd | Wholesale & retail | 2023 |
| Japanese MPV Motors Limited | Wholesale & retail | 2017 |
| Japaron Builders Limited | Construction | 1966 |
| Japonica Developments Limited | Real estate | 2020 |
| Japson Electric Ltd | Administrative & support | 2017 |
| Jaqqies Limited | Hospitality | 2025 |
| Jara Finance Ltd | Professional & scientific | 2024 |
| Jarass Ltd | Hospitality | 2026 |
| Jarava Homes Ltd | Real estate | 2024 |
| Jarcon Concrete Flooring Ltd | Construction | 2017 |
| Jardin Corrugated Cases Limited | Manufacturing | 1977 |
| Jarell Limited | Financial services | 2015 |
| Jarju Care Services Limited | Health & social care | 2019 |
| Jarju Studios Ltd | Real estate | 2025 |
| Jarmark Stores Limited | Wholesale & retail | 2022 |
| Jarmite Car Rentals Ltd | Administrative & support | 2019 |
| Jaro 852 Ltd | Financial services | 2025 |
| Jaroslaw Services Ltd | Transport & logistics | 2024 |
| Jarott Contracting Limited | Construction | 2017 |
| Jarrall Taxi Ltd | Transport & logistics | 2024 |
| Jarrett Realty Ltd | Real estate | 2020 |
| Jarron Developments Limited | Real estate | 2023 |
| Jarron Property Holdings Ltd | Real estate | 2022 |
| Jarron Property Management Limited | Real estate | 2026 |
| Jarusosha Ltd | Real estate | 2018 |
| Jarvis Global Services Limited | Wholesale & retail | 2025 |
| Jarvis Mullaley Limited | Construction | 2012 |
| JAS Bajwa Limited | Health & social care | 2018 |
| JAS Express Limited | Hospitality | 2025 |
| JAS Fresh Ltd | Wholesale & retail | 2024 |
| JAS Portfolio Ltd | Real estate | 2026 |
| Jasbir Sihota Limited | Administrative & support | 2016 |
| Jasc Bros Limited | Financial services | 2022 |
| Jaseea Ltd | Wholesale & retail | 2026 |
| Jash (DPS) Limited | Wholesale & retail | 2014 |
| Jash (DPS) Properties Ltd | Real estate | 2023 |
| Jash (Longbridge) Limited | Wholesale & retail | 2004 |
| Jashari Coffee Limited | Hospitality | 2024 |
| Jashu Retail Ltd | Wholesale & retail | 2023 |
| Jasilva Ltd | Other services | 2023 |
| Jasim Gloom Cards Ltd | Wholesale & retail | 2026 |
| Jasim Online Trading Ltd | Wholesale & retail | 2024 |
| Jasim Traders Limited | Manufacturing | 2021 |
| Jasims Ltd | Administrative & support | 2010 |
| Jasiva International Trade Investment UK Ltd | Real estate | 2019 |
| Jasjeet Steels Limited | Other services | 2025 |
| Jasjeev Limited | Other services | 2009 |
| Jasjeev Property Ltd | Real estate | 2019 |
| Jaskar Ltd | Financial services | 2019 |
| Jasm Accountancy Ltd | Professional & scientific | 2020 |
| Jasm Consultancy Ltd | Professional & scientific | 2023 |
| Jasmin Ltd | Wholesale & retail | 2022 |
| Jasminde UK Ltd | Real estate | 2013 |
| Jasmine 118 Ltd | Hospitality | 2017 |
| Jasmine Boora Ltd | Health & social care | 2023 |
| Jasmine House 121 Ltd | Hospitality | 2026 |
| Jasmine House Care Home Limited | Health & social care | 2007 |
| Jasmine Kendall Ltd | Professional & scientific | 2022 |
| Jasmine Palace 19 Ltd | Hospitality | 2025 |
| Jaso Limited | Wholesale & retail | 2008 |
| Jason Allatt Contracts Limited | Construction | 2018 |
| Jason Allen Limited | Extraterritorial | 2023 |
| Jason Fabrications Limited | | 1983 |
| Jason Meredith Interiors Limited | Manufacturing | 2016 |
| Jason's Rental Houses Ltd | Real estate | 2025 |
| JASONJONES1992 Limited | Information & communication | 2017 |
| Jasons Removals Limited | Transport & logistics | 2022 |
| Jaspal Taylor Ltd | Transport & logistics | 2025 |
| Jasper CF Limited | Financial services | 2010 |
| Jasper Private Equity Investments Limited | Financial services | 2023 |
| Jasper Private Equity Limited | Financial services | 2016 |
| Jaspreet K Studio Ltd | Arts & recreation | 2025 |
| Jassal and Sons Limited | Wholesale & retail | 2025 |
| Jassal Catering and Events Limited | Hospitality | 2017 |
| Jassal Flavours Ltd | Hospitality | 2017 |