| Jacsaru Ltd | Health & social care | 2024 |
| JAD Consultation Ltd | Administrative & support | 2014 |
| JAD Investments Limited | Real estate | 2014 |
| JAD Transport Ltd | Transport & logistics | 2019 |
| Jade 88 Limited | Hospitality | 2018 |
| Jade Pubco Ltd | Hospitality | 2024 |
| JAF Barber Ltd | Other services | 2023 |
| JAF Estates Ltd | Construction | 2020 |
| JAF Landscaping and Building Ltd | Construction | 2018 |
| Jaffer Homes Ltd | Real estate | 2021 |
| Jagan Joy Homes Ltd | Real estate | 2022 |
| Jaggard Properties Limited | Real estate | 2008 |
| Jaggards Limited | Professional & scientific | 2015 |
| Jahan Care Center Limited | Education | 2026 |
| JAI Ahluwalia Ecom Ltd | Wholesale & retail | 2026 |
| Jaipriya Ltd | Real estate | 2023 |
| Jairus Limited | Information & communication | 1999 |
| Jajt LLP | | 2018 |
| JAK Logistics Ltd | Transport & logistics | 2013 |
| Jakande Logistics Ltd | Transport & logistics | 2026 |
| Jakarta (UK) Limited | Wholesale & retail | 2009 |
| Jake Carter Limited | Wholesale & retail | 2017 |
| Jake Mason Roofing Limited | Construction | 2022 |
| Jake Peachey Limited | Administrative & support | 2026 |
| Jakub Kajor Ltd | Construction | 2018 |
| Jakub Transport Ltd | Transport & logistics | 2015 |
| Jals Consultancy and Entertainments Ltd | Professional & scientific | 2026 |
| JAM Factory AI Ltd | Information & communication | 2026 |
| JAM Group Investments Ltd | Financial services | 2023 |
| JAM Rail Engineering Ltd | Construction | 2026 |
| Jamaican Delights Ltd | Hospitality | 2013 |
| James Chatwin Landscapes Ltd | Administrative & support | 2015 |
| James International Automotive Group Services Ltd | Wholesale & retail | 2025 |
| James Smith Electrical Limited | Construction | 2025 |
| James Sutton Farming Company Limited | Agriculture & fishing | 1953 |
| James West Architecture Ltd | Professional & scientific | 2023 |
| Jamhut Ltd | Information & communication | 2024 |
| Jamia Bukharia Qadiriyyah Ltd | Education | 2023 |
| Jamie a Rose Limited | Wholesale & retail | 2020 |
| Jamie Gidney Consultancy Ltd | Professional & scientific | 2025 |
| Jamie Jacobs Properties Limited | Real estate | 2024 |
| Jamie Shaw Design Limited | Professional & scientific | 2020 |
| Jammy Bread Limited | Professional & scientific | 2018 |
| Jammy's Cleaning Services Limited | Administrative & support | 2018 |
| Jams Consultancy Services Ltd | Professional & scientific | 2023 |
| Jamtah Foods Ltd | Hospitality | 2018 |
| Jamuel Care Limited | Health & social care | 2021 |
| JAN Brooke Environmental Consultant Limited | Professional & scientific | 2002 |
| JAN Service Ltd | Transport & logistics | 2022 |
| JAN Stach Ltd | Transport & logistics | 2014 |
| Jandomel Ltd | Health & social care | 2012 |
| Jane Carr Limited | Manufacturing | 2005 |
| Jangana Camara Ltd | Professional & scientific | 2024 |
| Janice Kendrick Design Services Limited | Professional & scientific | 1989 |
| Janish Homes Limited | Construction | 2018 |
| Jannat Food Stores Ltd | Wholesale & retail | 2016 |
| Jans Life Ltd | Health & social care | 2015 |
| Janson Hong Limited | Wholesale & retail | 2014 |
| Januka Ltd | Hospitality | 2023 |
| Jaola Designs Limited | Professional & scientific | 2021 |
| Japanesene Ltd | Wholesale & retail | 2024 |
| Japsco Limited | Construction | 2015 |
| Jarmq Ltd | Construction | 2018 |
| Jarryd Limited | Construction | 2015 |
| JAS Engineering Solutions Limited | Professional & scientific | 2023 |
| Jasimo Limited | Administrative & support | 2020 |
| Jasmine Massage and Spa Ltd | Other services | 2020 |
| Jason Church Electrical Ltd | Construction | 2020 |
| Jaspar Housing Ltd | Real estate | 2022 |
| Jaspar Solutions Ltd | Information & communication | 2018 |
| Jassar Capital Limited | Real estate | 2026 |
| Jassar Developments Limited | Construction | 2005 |
| Jassar Investments Ltd | Real estate | 2018 |
| Jassar Private Limited | Hospitality | 2021 |
| Jastal Ltd | Hospitality | 2014 |
| Jatalie Holdings Limited | Real estate | 2021 |
| Jauhar Services Limited | Health & social care | 2021 |
| Javvy Control and Automation Ltd | Professional & scientific | 2025 |
| Jawahar Property Limited | Real estate | 2025 |
| JAY and Noah Healthcare Ltd | Administrative & support | 2021 |
| JAY Hill Property Services Ltd | Real estate | 2025 |
| JAY K Projects Ltd | Construction | 2014 |
| JAY Lettings Limited | Real estate | 2006 |
| JAY Painting and Decorating Ltd | Construction | 2023 |
| JAY Ragi Limited | Information & communication | 2023 |
| Jay-Hill Property, Cleaning and Security Services Ltd | Real estate | 2022 |
| Jaychizzy Ltd | Professional & scientific | 2025 |
| Jaydee Brook Limited | Manufacturing | 2009 |
| JAZ Travel Ltd | Transport & logistics | 2024 |
| Jaze Transport Ltd | Transport & logistics | 2026 |
| Jazzys Car Sales Ltd | Wholesale & retail | 2025 |
| JB Accounting Services Ltd | Professional & scientific | 2023 |
| JB Building & Landscape Services Ltd | Construction | 2017 |
| JB Engineer Ltd | Professional & scientific | 2020 |
| JB Farms (Poland) Limited | Financial services | 2018 |
| JB Management Solutions Ltd | Professional & scientific | 2021 |
| JB Packaging Solutions Limited | Administrative & support | 2009 |
| JB Production Services Ltd | Arts & recreation | 2017 |
| JB Translogistics Ltd | Administrative & support | 2012 |
| Jbac Installations Ltd | Construction | 2025 |