| J1BARBER Ltd | Other services | 2025 |
| J1MMY Limited | Extraterritorial | 2020 |
| J26@M62 Limited | Real estate | 2019 |
| J3 JAL Limited | Financial services | 2021 |
| J4CK Ltd | Extraterritorial | 2015 |
| J4COB Limited | Extraterritorial | 2018 |
| J4SON Limited | Extraterritorial | 2017 |
| JAC ALL Investments Limited | Administrative & support | 2023 |
| Jack Brilleaux Ltd | Professional & scientific | 2022 |
| Jack Morgan Construction Ltd | Construction | 2025 |
| Jack Pearce Daniels Consulting Ltd | Information & communication | 2013 |
| Jackie Lincoln Associates Limited | Professional & scientific | 2011 |
| Jackson Foxx Limited | Extraterritorial | 2025 |
| Jackson Street Apartments Ltd | Households | 2012 |
| Jacob Bradley Trading Company Limited | Wholesale & retail | 2025 |
| Jacqueline Boole Sculptural Ceramics LLP | | 2026 |
| Jacqui Hall Limited | Professional & scientific | 2025 |
| Jaden Limited | Extraterritorial | 2012 |
| JAE Patrick Investments Limited | Real estate | 2024 |
| JAE Property Solutions Limited | Real estate | 2025 |
| Jaff Properties Ltd | Real estate | 2019 |
| Jake Anthony Limited | Professional & scientific | 2008 |
| Jakie Limited | Extraterritorial | 2013 |
| Jakob Oliver Limited | Professional & scientific | 2019 |
| JAM1E Limited | Extraterritorial | 2020 |
| James Allen Enterprises Ltd | Transport & logistics | 2025 |
| James Bentham Farrier Limited | Arts & recreation | 2025 |
| James Brown Catering Ltd. | Hospitality | 2014 |
| James Carson Construction Group Ltd | Construction | 2020 |
| James Coleman Logistics Ltd | Transport & logistics | 2023 |
| James D Whitaker Graphic Design Ltd | Professional & scientific | 2023 |
| James Frank Limited | Wholesale & retail | 2015 |
| James S. Brayshaw Limited | Hospitality | 1964 |
| James Spencer Estates & Co Limited | Real estate | 1997 |
| James T Rule Ltd | Professional & scientific | 2019 |
| James Thompson Consulting Spofforth Limited | Information & communication | 2017 |
| James Wall Associates Limited | Information & communication | 2006 |
| James Wilby Holdings Limited | Real estate | 1977 |
| James Wood (Automotive Refinishers) Ltd | Wholesale & retail | 2011 |
| Jamil Malik Consultancy Services Limited | Professional & scientific | 2026 |
| Jandl Prestige Properties Ltd | Construction | 2025 |
| Jane Caress Limited | Health & social care | 2012 |
| Jane Hill Ltd | Professional & scientific | 2020 |
| Jane Katherine Houghton Ltd | Professional & scientific | 2018 |
| Jane Wood Ltd | Professional & scientific | 2026 |
| Janes Allen Enterprises Ltd | Transport & logistics | 2025 |
| Janie Wilson Candles Limited | Wholesale & retail | 2014 |
| Janine KOT (JK) Recruitment Advisory Services Limited | Professional & scientific | 2015 |
| JAP UK Holdings Ltd | Professional & scientific | 2026 |
| JAR Capital Group Limited | Wholesale & retail | 2023 |
| Jardel Leisure Ltd | Administrative & support | 2019 |
| Jarfull Limited | Wholesale & retail | 2017 |
| JARV1S Limited | Extraterritorial | 2020 |
| Jarvis Investments | Financial services | 2019 |
| Jarvis Pentelow Limited | Wholesale & retail | 2024 |
| Jarvis Roach Limited | Extraterritorial | 2025 |
| Jarvis Spencer Limited | Extraterritorial | 2025 |
| Jason Beresford Limited | Information & communication | 2017 |
| Jason Pink Limited | Extraterritorial | 2026 |
| Jason Proudley (Haulage) Ltd | Transport & logistics | 2015 |
| Jasper Fenimore Limited | Extraterritorial | 2025 |
| Jasper Yorke Limited | Wholesale & retail | 2022 |
| Jawa Steel & Grain Ltd | Manufacturing | 2025 |
| Jazzy B Productions Limited | Arts & recreation | 2024 |
| JB Cool Trade Ltd | Wholesale & retail | 2019 |
| JB Dentures Limited | Health & social care | 2018 |
| JB Padel Courts UK Ltd | Construction | 2024 |
| JB Printing Limited | Manufacturing | 2025 |
| JB Retail Solutions Ltd | Professional & scientific | 2013 |
| JBE (UK) Limited | Real estate | 2005 |
| JBF Property Limited | Real estate | 2016 |
| Jbshealth Ltd | Health & social care | 2024 |
| JC Robinson Properties Ltd | Real estate | 2019 |
| Jchu Limited | Real estate | 2020 |
| JCT Groundworks Limited | Construction | 2022 |
| JD Property & Lets Ltd | Real estate | 2020 |
| Jd's Hot Honey Ltd | Wholesale & retail | 2021 |
| JDH Technical Services Limited | Manufacturing | 2014 |
| JDM Growth Consultancy Ltd | Professional & scientific | 2026 |
| JDR DESIGN-3D Ltd | Manufacturing | 2023 |
| JDS Independent Technical Services Ltd | Construction | 2001 |
| Jeff Parris Limited | Professional & scientific | 2010 |
| Jego (Harrogate) Limited | Administrative & support | 2017 |
| JEH Planning Limited | Professional & scientific | 2019 |
| Jelly Accounts Ltd | Professional & scientific | 2018 |
| Jelly and Bean Limited | Information & communication | 2004 |
| Jelly Properties Ltd | Real estate | 2020 |
| Jellyfish Technologies Ltd | Information & communication | 2024 |
| Jelme Ltd | Administrative & support | 2025 |
| Jennie Bullock Children's Therapy Limited | Education | 2017 |
| Jennings Properties Ltd | Hospitality | 2022 |
| Jennyfield Barbers Ltd | Other services | 2021 |
| Jennygee Healthcare Services Limited | Health & social care | 2019 |
| Jenron Limited | Extraterritorial | 2026 |
| Jensch & Jensch Consulting Ltd | Professional & scientific | 2025 |
| Jenti Property Limited | Real estate | 2026 |
| Jered Sorkin Music Limited | Information & communication | 2009 |
| Jeremy Allott Decorators Ltd | Construction | 2019 |
| Jeremy Bridgeman Hairdressing Limited | Other services | 2009 |
| Jeremy Charlton Ltd | Health & social care | 2015 |