| JMJ Diagnostics Limited | Health & social care | 2023 |
| JMJ Estates Ltd | Real estate | 2025 |
| JMJ Groundworks Ltd | Construction | 2023 |
| JMJ Group Holdings Ltd | Financial services | 2025 |
| JMJ Hospitality Limited | Hospitality | 2022 |
| JMJ Plant Hire Ltd | Administrative & support | 2025 |
| JMP Consultancy Ltd | Professional & scientific | 2022 |
| JMS (Devon) Limited | Construction | 2023 |
| JMS Construction (West) Limited | Construction | 2013 |
| JMS Developments (South West) Limited | Construction | 2001 |
| JMT Wood Build Ltd | Construction | 2013 |
| JMW Arboriculture Ltd | Agriculture & fishing | 2024 |
| JN Technical Ltd | Administrative & support | 2013 |
| JNG Surveys Ltd | Professional & scientific | 2015 |
| JNJ MCS Ltd. | Hospitality | 2019 |
| JO Downs Glass Design Limited | Manufacturing | 2004 |
| JO Downs Limited | Manufacturing | 2022 |
| JO Fisher & Co Limited | Health & social care | 2012 |
| JO Lightfoot Limited | Education | 2022 |
| Joanna Webber Therapy Ltd | Health & social care | 2024 |
| Jobfam Ltd | Information & communication | 2025 |
| Joda Limited | Real estate | 2021 |
| Jodi Locks Ltd | Other services | 2019 |
| JOE Dunn Plant Limited | Manufacturing | 2020 |
| JOE Hassell Command Ltd | Public administration | 2023 |
| JOE Mcclenaghan Limited | Construction | 2017 |
| Joe's Pedals Ltd | Administrative & support | 2010 |
| Johansen & Co (UK) Limited | Professional & scientific | 2016 |
| Johar Limited | Wholesale & retail | 1989 |
| John Cordy Limited | Information & communication | 2022 |
| John D.Gifford(Properties)Limited | Construction | 1959 |
| John David Estate Agents Limited | Real estate | 2012 |
| John Harris Art Limited | Arts & recreation | 2010 |
| John Hill Electric (Exeter) Limited | Real estate | 1957 |
| John Levers Way Management Company Limited | Households | 2011 |
| John Raymond Ltd | Transport & logistics | 2020 |
| John Stanbrook Limited | Professional & scientific | 2020 |
| John Todd Refrigeration Limited | Manufacturing | 2003 |
| Johns Holdings Ltd | Financial services | 2022 |
| Johnstone Medical Ltd | Health & social care | 2019 |
| Joiin Ltd | Information & communication | 2017 |
| Joinery Production Services Ltd | Information & communication | 2024 |
| Joint Homes Ltd | Real estate | 2017 |
| Joint Interiors Limited | Construction | 2014 |
| Jojo (Leisure) Limited | Real estate | 2000 |
| JON Marshall Ltd | Professional & scientific | 2022 |
| JON Stone Surveyors Ltd | Real estate | 2015 |
| Jonathan Bardgett Limited | Professional & scientific | 2012 |
| Jonathan Bishop Limited | Financial services | 2022 |
| Jonathan Blake Money Management Limited | Financial services | 2004 |
| Jonathan Collins & Co. Limited | Professional & scientific | 2020 |
| Jonathan Johns Limited | Construction | 2010 |
| Jonathan Wilkes Therapy Limited | Health & social care | 2023 |
| Jones Belgravia Limited | Hospitality | 2020 |
| Jones Legal Ltd | Professional & scientific | 2023 |
| Jonjo Holdings Ltd | Hospitality | 2020 |
| Jonny Tooze Physiotherapy Services Limited | Professional & scientific | 2007 |
| JORD4N Building Ltd | Construction | 2021 |
| JORD4N Lettings Ltd | Real estate | 2022 |
| JORD4N Properties Limited | Real estate | 2020 |
| Jordan Assante Holdings Limited | Financial services | 2016 |
| Jordan Assante Limited | Financial services | 2022 |
| Jordan Hebburn Holdings Ltd | Financial services | 2024 |
| Jordan Holdings (SW) Limited | Real estate | 2020 |
| Jordan of Limited | Information & communication | 2024 |
| Jordans Carpentry Limited | Manufacturing | 2015 |
| Jose Sirvent Ltd | Professional & scientific | 2020 |
| Joshua's Harvest Limited | Administrative & support | 2000 |
| Josi Homes Ltd | Real estate | 2019 |
| Josiahs Enterprise Ltd | Health & social care | 2024 |
| Journeys That Care Ltd | Health & social care | 2022 |
| Joyce & Broomes Ltd | Real estate | 2018 |
| Joyfulcart Ltd | Wholesale & retail | 2024 |
| Joymi House Limited | Wholesale & retail | 2015 |
| JP Equestrian Pro Limited | Wholesale & retail | 2018 |
| JP Gardens Ltd | Administrative & support | 2025 |
| JP MAP Graphics Ltd | Professional & scientific | 1998 |
| JP Mulholland Holdings Ltd | Financial services | 2023 |
| JPC New Home Ltd | Construction | 2026 |
| Jpdjpd Ltd | Real estate | 2019 |
| JPE Southwest Ltd | Real estate | 2020 |
| JPL Civil & Structural Engineering Ltd | Professional & scientific | 2026 |
| JPS Event Consultancy Ltd. | Arts & recreation | 2011 |
| Jpsd Properties Limited | Real estate | 2014 |
| JPT 2 Limited | Wholesale & retail | 1946 |
| JPW Scaffolding (South West) Limited | Construction | 2019 |
| JR Carpentry (Devon) Ltd | Construction | 2021 |
| JR Optical Services Limited | Wholesale & retail | 2014 |
| JRC Consulting Engineers Limited | Professional & scientific | 2017 |
| Jrdl UK Ltd | Wholesale & retail | 2017 |
| JRL Developments Devon Ltd | Real estate | 2016 |
| JS Cars Exeter Ltd | Wholesale & retail | 2015 |
| JS Landa Properties Limited | Real estate | 2026 |
| JS Roofing SW Ltd | Construction | 2025 |
| JS South West Ltd | Financial services | 2026 |
| JSB Gardening and Handy MAN Services Ltd | Households | 2022 |
| Jscc Services Limited | Administrative & support | 2019 |
| JSE Clarence Limited | Real estate | 2021 |
| JSH Capital Limited | Other services | 2017 |
| JSK Couriers Ltd | Transport & logistics | 2022 |