| J a Aldridge Ltd. | Construction | 2023 |
| J B Wilkinson Prop Master Limited | Real estate | 2016 |
| J D Pearce Limited | Real estate | 1993 |
| J Doyle Carpentry Ltd | Construction | 2021 |
| J Holland Plumbing and Heating Ltd | Construction | 2021 |
| J Straker, Chadwick & Sons Limited | Professional & scientific | 2010 |
| J W Property and Garden Maintenance Ltd | Construction | 2026 |
| J&N Civils Ltd | Construction | 2019 |
| Jacobear Limited | Construction | 2025 |
| Jake Crockett Construction Ltd | Construction | 2024 |
| JAM Ceramics Ltd | Construction | 2025 |
| James & Field Ltd | Health & social care | 2019 |
| James and Slater Developments Limited | Other services | 2017 |
| Jarrett Partners Limited | Professional & scientific | 2014 |
| Jasmine Nails 68 Ltd | Other services | 2024 |
| JC Moulding Limited | Manufacturing | 2014 |
| JD Formwork Limited | Construction | 2016 |
| JD Hockey Services Ltd | Construction | 2025 |
| JD Morgan Education Limited | Education | 2023 |
| JEL Construction & Surveying Ltd. | Construction | 2024 |
| Jenkins Legal Services (Trading AS JLS) Limited | Administrative & support | 2012 |
| Jerboa Media Ltd | Information & communication | 2014 |
| Jessica Pycroft Limited | Professional & scientific | 2023 |
| Jestell Limited | Construction | 2013 |
| JJ Agriculture Limited | Financial services | 2022 |
| JJ Electrical (Sussex) Limited | Construction | 2016 |
| JK Risk Management Ltd | Financial services | 2025 |
| JL Financial Planning Ltd | Financial services | 2018 |
| JL Wealth Management Ltd | Financial services | 2018 |
| Jlmtherapy Limited | Other services | 2024 |
| JLS & HMS Holdings Limited | Professional & scientific | 1990 |
| JLS & HMS Stores Limited | Real estate | 1990 |
| JM Clinical Research Ltd | Professional & scientific | 2024 |
| JM Jets Ltd | Administrative & support | 2024 |
| JMR 2000 Limited | Real estate | 2014 |
| Jmrmc Ltd | Extraterritorial | 2018 |
| John O'Sullivan & Sons,Limited | Real estate | 1921 |
| Jones and SON Build Group Limited | Construction | 2025 |
| Jono Jones Ltd | Arts & recreation | 2021 |
| Joolz Properties Ltd | Real estate | 2019 |
| Jordans Surfacing Contractors Ltd | Construction | 2024 |
| Jordans Surfacing Ltd | Construction | 2017 |
| Joshua Tree Services Ltd | Agriculture & fishing | 2020 |
| JP Independent Financial Advisers Ltd | Financial services | 2019 |
| JRC Electrical Services Ltd | Construction | 2018 |
| JSP Accountancy Ltd | Professional & scientific | 2021 |
| JTM Group Holdings Ltd | Financial services | 2026 |
| JTM Property Ltd | Real estate | 2026 |
| Judd Brothers Holdings Limited | Financial services | 2021 |
| Judd Brothers Limited | Wholesale & retail | 2021 |
| Just Flats Limited | Real estate | 2015 |
| JV Storage LLP | | 2015 |
| K and M Hill Limited | Real estate | 2016 |
| K'Cal Dietetics Limited | Health & social care | 2019 |
| Kaan NAZ Ltd | Real estate | 2026 |
| Kabyn Ltd | Professional & scientific | 2020 |
| Kahve Catering & Entertainment Ltd | Hospitality | 2018 |
| Kara (Burghfield) Limited | Manufacturing | 2007 |
| Kasauli Ltd | Professional & scientific | 2013 |
| KDJ Property Development Limited | Construction | 2018 |
| Keep Abergavenny Warm CIC | Health & social care | 2025 |
| Keith Price Garages Limited | Wholesale & retail | 1986 |
| Kelho Developments Limited | Construction | 2012 |
| Kelkeochicks Ltd | Hospitality | 2021 |
| KH & JK Services Ltd | Wholesale & retail | 2020 |
| Kids Cafe Abergavenny Ltd | Hospitality | 2024 |
| KIM Balaskas Limited | Other services | 2013 |
| Kimax Estates Limited | Construction | 2005 |
| Kimax Ventures Limited | Construction | 2023 |
| Kingdom Come (Abergavenny) Ltd | Arts & recreation | 2024 |
| Kingdom Seating Limited | Manufacturing | 1981 |
| Kingsley CIS Limited | Information & communication | 2017 |
| Kinvara Homes Limited | Construction | 2009 |
| Kipper's Kabs Ltd | Transport & logistics | 2017 |
| Kirby 123 Limited | Hospitality | 2016 |
| Kitup Limited | Wholesale & retail | 2021 |
| Kopec Ltd | Construction | 2005 |
| L a T Hospitality Limited | Hospitality | 2016 |
| L.B.H. Transport Services Limited | Information & communication | 1972 |
| L.J. Cook & Sons Limited | Wholesale & retail | 1987 |
| LA Petite Fleur Ltd | Wholesale & retail | 2022 |
| Ladybirds at Llanvihangel Ltd | Education | 2009 |
| Lains Consultancy Ltd | Professional & scientific | 1999 |
| Lamia Corporate Vehicle Management Limited | Wholesale & retail | 2006 |
| Land Solutions (South) Ltd | Construction | 2012 |
| Landsdown Properties Ltd | Households | 2018 |
| Landtec Surveys Limited | Administrative & support | 2006 |
| Lanes Garage & Recovery Services Ltd | Wholesale & retail | 2024 |
| Lanes Garage (Abergavenny) Limited | Wholesale & retail | 2018 |
| Lanes Recovery (Gloucester) Limited | Wholesale & retail | 2026 |
| Lazthai Ltd | Hospitality | 2023 |
| Lbir Ltd | Health & social care | 2023 |
| LD2 Developments Ltd | Real estate | 2021 |
| Leah Care Services Ltd | Health & social care | 2019 |
| Lean Structures Ltd | Professional & scientific | 2020 |
| Leeder Homes & Investment Ltd | Real estate | 2026 |
| Lesbirel Property Investments Limited | Real estate | 2017 |
| Lester Group Holdings Limited | Financial services | 2025 |
| Lester Medical Limited | Health & social care | 2010 |
| Lester Oncology Limited | Health & social care | 2016 |