| Jmdn Media Limited | Information & communication | 2019 |
| JME Accounts & Payroll Ltd | Professional & scientific | 2017 |
| JMG Assets Group Ltd | Real estate | 2025 |
| JMG Homestores Ltd | Wholesale & retail | 2014 |
| JMP International Ltd | Wholesale & retail | 2025 |
| Jmrukdigitalstore Ltd | Wholesale & retail | 2025 |
| JMS Breakers Ltd | Water & waste | 2014 |
| JMS Renovation Ltd | Construction | 2024 |
| Jmscards Limited | Wholesale & retail | 2021 |
| Jnbn Services Ltd | Financial services | 2026 |
| JNM Engineering Ltd | Professional & scientific | 2006 |
| JNP Cloud Limited | Other services | 2021 |
| JNP Homes Limited | Real estate | 2025 |
| Jobmerger Support Services Ltd | Health & social care | 2019 |
| Jodlowski International Ltd | Professional & scientific | 2026 |
| Jodor Ltd | Other services | 2018 |
| Joeddy Limited | Health & social care | 2022 |
| Joedeen Limited | Wholesale & retail | 2025 |
| Johal Ventures Ltd | Financial services | 2021 |
| Johdo Services Ltd | Information & communication | 2023 |
| John & Jeff's LLP | | 2023 |
| John Bliss Limited | Wholesale & retail | 2003 |
| John Charles Homes Limited | Real estate | 2013 |
| John COX Consulting Ltd | Professional & scientific | 2024 |
| John Hill Building Contractors Limited | Construction | 2013 |
| John Keen Limited | Wholesale & retail | 2016 |
| John Marshall Ltd | Professional & scientific | 2023 |
| John Mediapro Ltd | Information & communication | 2023 |
| John Price Roofing Contractors Limited | Construction | 2020 |
| John Smalley Associates Ltd | Professional & scientific | 2020 |
| JOHN6MEDIA Limited | Wholesale & retail | 2020 |
| Johnson Renovations Limited | Construction | 2002 |
| Johnson Skip Hire Ltd | Water & waste | 2023 |
| Joint Maintenance Limited | Construction | 2019 |
| Jolema Housing Group Limited | Real estate | 2024 |
| Jolly Good Car Spares Ltd | Wholesale & retail | 2008 |
| Jolly Pursuit Ltd | Information & communication | 2018 |
| Jomo Property Ltd | Real estate | 2025 |
| Jonathan Harris Studio Glass Limited | Manufacturing | 2000 |
| Jones Platforms Limited | Professional & scientific | 2023 |
| Jonny Kendrick Leadership Coaching & Consultancy Ltd | Professional & scientific | 2025 |
| Jonyrah Construct Ltd | Real estate | 2020 |
| Joseph Heer Homes Limited | Construction | 2024 |
| Josmat Healthcare Limited | Health & social care | 2025 |
| Joul Properties Limited | Real estate | 2023 |
| Jovac Ltd | Other services | 2024 |
| Jovid Community Housing CIC | Real estate | 2026 |
| Jovid Ltd | Real estate | 2018 |
| Joy in a Box Ltd | Wholesale & retail | 2017 |
| JP Cornerstone Ltd | Construction | 2026 |
| JP Fruits Limited | Wholesale & retail | 2008 |
| JP Gearbox Limited | Wholesale & retail | 2019 |
| JP Storage Solutions Ltd | Manufacturing | 2022 |
| JPF Care Solutions Ltd | Health & social care | 2021 |
| JPW Scoop 6 Club Limited | Arts & recreation | 2017 |
| JR Andre Ltd | Arts & recreation | 2021 |
| JR Lettings Ltd | Real estate | 2018 |
| JR13 Holdings Limited | Financial services | 2020 |
| JRM Holdings Limited | Wholesale & retail | 2008 |
| JRO Mechanical Services Ltd | Manufacturing | 2017 |
| JSB Electrical (Telford) Ltd | Construction | 2025 |
| JSC Cleaning Ltd | Administrative & support | 2026 |
| Jsem Solutions Limited | Professional & scientific | 2023 |
| JSH Haulage Ltd | Transport & logistics | 2024 |
| JSJ Management Consulting Limited | Professional & scientific | 2013 |
| JSS Trans Limited | Transport & logistics | 2023 |
| Jssdent Ltd | Health & social care | 2023 |
| JT Castings Limited | Manufacturing | 2009 |
| JT Developments (Midlands) Limited | Construction | 2016 |
| JT Heating Services (Shropshire) Ltd | Construction | 2020 |
| JT Safety Projects Limited | Construction | 2020 |
| JT Tech Solutions Ltd | Information & communication | 2025 |
| JU Retailers Ltd | Wholesale & retail | 2024 |
| JUA Properties Limited | Real estate | 2023 |
| Jugaar Ltd | Wholesale & retail | 2023 |
| Juice LAB Plus Ltd | Wholesale & retail | 2023 |
| Jules Convenience Limited | Wholesale & retail | 2005 |
| Julia Weston Lettings & Co Limited | Real estate | 2008 |
| Julie's Shines Limited | Administrative & support | 2018 |
| Junction 70 Ltd | Information & communication | 2022 |
| Jungle HR Ltd | Professional & scientific | 2008 |
| Jungleland (UK) Ltd | Arts & recreation | 2012 |
| Junie Ltd | Health & social care | 2015 |
| Juniper Tree Computing Limited | Information & communication | 2007 |
| Just Computer Technology Limited | Other services | 2019 |
| Just Kreative Events Ltd | Hospitality | 2018 |
| Just Sign UP Limited | Wholesale & retail | 2016 |
| Justbagzz Ltd | Wholesale & retail | 2021 |
| JUSTBMW24-7 Limited | Other services | 2016 |
| Justiacore Limited | Information & communication | 2025 |
| JVR Developments Ltd | Construction | 2021 |
| JW & SH Enterprises Limited | Construction | 2015 |
| JW RVS Limited | Administrative & support | 2024 |
| Jwilberforce Limited | Health & social care | 2015 |
| Jwilco Limited | Health & social care | 2025 |
| J’S Anatomy Ltd | Extraterritorial | 2024 |
| K & C Property Management Limited | Real estate | 2017 |
| K & S Plantscapes Limited | Administrative & support | 2021 |
| K and N Care Solutions Ltd | Professional & scientific | 2026 |
| K B Decorating Ltd | Construction | 2020 |