| Island Spirit C.I.C. | Administrative & support | 2012 |
| Itel Limited | Information & communication | 2009 |
| IVY House Creamery Limited | Wholesale & retail | 2007 |
| IVY House Farm Limited | Agriculture & fishing | 2017 |
| J & G Upshall Transport Limited | Transport & logistics | 2002 |
| J and a Barter Properties Limited | Real estate | 2017 |
| J B Kerr Stone Repair & Conservation Services Ltd | Construction | 2015 |
| J Infinity Ltd | Wholesale & retail | 2026 |
| J Taylor Roofing Services South West Limited | Construction | 2022 |
| J W Aquisitions Ltd | Real estate | 2014 |
| J Witt Limited | Wholesale & retail | 2021 |
| J-Type Audio Ltd | Wholesale & retail | 2024 |
| J.C. Joinery Limited | Manufacturing | 1996 |
| J.F. Padwick & Co Electrical Limited | Construction | 1973 |
| J.R. Harding & Sons (Frome) Limited | Transport & logistics | 1975 |
| Jack Hudson Ltd | Arts & recreation | 2019 |
| Jackdaws (Coach House) Limited | Real estate | 2001 |
| Jackdaws Educational Trust | Arts & recreation | 1994 |
| Jahor Group Ltd | Financial services | 2025 |
| Jailmake Limited | Manufacturing | 2014 |
| JAM Tomorrow Productions Limited | Administrative & support | 2020 |
| Jamanda Holdings Limited | Health & social care | 2016 |
| Jamanda Properties Ltd | Real estate | 2021 |
| James Brown Limited | Arts & recreation | 2012 |
| James Joyce Limited | Arts & recreation | 2011 |
| James Lock Limited | Professional & scientific | 2026 |
| James Morrison Catering Ltd | Hospitality | 2015 |
| James White Transport Ltd | Transport & logistics | 2014 |
| Jamie Mcelwain Web Design Ltd. | Information & communication | 2017 |
| Jamie Molloy Ltd. | Professional & scientific | 2023 |
| Janus Stone Limited | Real estate | 2026 |
| Jason Malone Digital Ltd | Professional & scientific | 2020 |
| Jason Samosa Ltd | Information & communication | 2026 |
| Jatox Limited | Professional & scientific | 2014 |
| Jay-El Ltd | Professional & scientific | 2025 |
| Jaymex Limited | Information & communication | 2018 |
| Jazz Tyres Limited | Wholesale & retail | 2016 |
| JB Recycling Engineer Ltd | Manufacturing | 2021 |
| JD Property Management and Development Limited | Real estate | 2025 |
| JDS Toys & Games Limited | Wholesale & retail | 2005 |
| Jeevitha Convenience Ltd | Wholesale & retail | 2025 |
| Jellywatt Renewables Ltd | Professional & scientific | 2025 |
| Jessica Weeks Treglown Limited | Professional & scientific | 2020 |
| JF MOT Centre Limited | Wholesale & retail | 2010 |
| JFR Flooring Ltd | Administrative & support | 2019 |
| JHM Consulting Ltd | Professional & scientific | 2012 |
| JJN Publishing Ltd | Information & communication | 2021 |
| JL Wine Consultancy Limited | Professional & scientific | 2017 |
| Jljs Construction Ltd | Construction | 2023 |
| Jljs Properties Ltd | Real estate | 2025 |
| JM Fencing & Landscaping Ltd | Administrative & support | 2020 |
| JM Leisure Investments Ltd | Hospitality | 2024 |
| JMH Workshop Limited | Manufacturing | 2020 |
| JMJ 72 Ltd | Financial services | 2024 |
| JO Berryman Studio Limited | Other services | 2008 |
| JO Byron Fundraising Limited | Professional & scientific | 2015 |
| Joanie Films Ltd | Information & communication | 2018 |
| JOB Centre Limited | Administrative & support | 2008 |
| Joel Whalley Property Estates Ltd | Real estate | 2025 |
| John Darville Limited | Administrative & support | 2015 |
| John Shepherd Ltd | Education | 2014 |
| John Yerbury Property Developments Limited | Real estate | 1999 |
| Johnny Szymanski Limited | Wholesale & retail | 2024 |
| JON Betts Tattoos & Prints Limited | Arts & recreation | 2019 |
| Jonathan Bayliss Surveyors Ltd | Professional & scientific | 2011 |
| Jonathan Tibbs Woodworks Ltd | Administrative & support | 2018 |
| Jones Production Services Ltd | Arts & recreation | 2025 |
| Josh Holland Transport Ltd | Transport & logistics | 2026 |
| JPF Built Heritage Limited | Professional & scientific | 2012 |
| JPG Construction SW Ltd | Construction | 2022 |
| JPS Civil Engineering Ltd | Construction | 2014 |
| JTA Services Southwest Ltd | Water & waste | 2024 |
| Jump UP and Kiss ME Ltd | Wholesale & retail | 2026 |
| Juncta Limited | Information & communication | 2026 |
| Juniper Lane Limited | Real estate | 2025 |
| Junkan Limited | Information & communication | 2026 |
| Juntos Media Ltd | Professional & scientific | 2026 |
| Just a Chance Limited | Other services | 2009 |
| Just Grab Ltd | Water & waste | 2014 |
| JW Accountancy (SW) Limited | Professional & scientific | 2022 |
| JY Interiors Ltd | Construction | 2023 |
| K C Brown Builders Limited | Construction | 1994 |
| K S Welling Limited | Wholesale & retail | 2022 |
| K Taylor Commercial Vehicle Services Ltd | Wholesale & retail | 2004 |
| K W Brake and SON Limited | Agriculture & fishing | 2008 |
| K. Gregory Construction Ltd | Construction | 2010 |
| K. W. Edwards Limited | Construction | 2002 |
| K2 (Wells) Limited | Construction | 2013 |
| Kaay Investments Limited | Real estate | 2023 |
| Kabulee Spice Limited | Hospitality | 2023 |
| Kaiasm Ltd | Professional & scientific | 2010 |
| Kaiketsu Property Limited | Real estate | 2018 |
| Kaju Massala Limited | Hospitality | 2023 |
| Kaland Events Limited | Hospitality | 2025 |
| Kally Consulting Ltd | Administrative & support | 2023 |
| Kamila Kaim Limited | Health & social care | 2011 |
| Kando AV Ltd | Professional & scientific | 2025 |
| Kate Downey Art Limited | Arts & recreation | 2017 |
| Kavicare Limited | Health & social care | 2015 |
| KB Movement & Therapy Ltd | Education | 2018 |