| Innis Suntime Company Limited(The) | Hospitality | 1983 |
| INOV8IONS Ltd | Information & communication | 2026 |
| Insightful Solutions Limited | Health & social care | 2009 |
| Inspirio Limited | Information & communication | 2006 |
| Instant Access Europe Limited | Wholesale & retail | 2018 |
| Internet Centre Limited | Extraterritorial | 2012 |
| Internet Communications (Services) Limited | Information & communication | 2021 |
| Interplan Imaging Ltd | Health & social care | 2010 |
| Introvice Ltd | Information & communication | 2017 |
| Intu Sport Limited | Wholesale & retail | 2016 |
| ISO Certification Limited | Professional & scientific | 2017 |
| Iteq Electrical & Solar Limited | Construction | 2007 |
| It’S Your Lucky Day Competitions Ltd | Arts & recreation | 2025 |
| J & a Consulting Limited | Information & communication | 1997 |
| J D B Electrical Ltd | Construction | 2013 |
| J Green Property Management Limited | Real estate | 2007 |
| J K W Prints Limited | Wholesale & retail | 2020 |
| J Wilson Group Limited | Construction | 2025 |
| J. Bascombe Contractors Limited | Agriculture & fishing | 1983 |
| J.K.L.(Enterprises) Limited | Construction | 2004 |
| JAB Motor Company Limited | Wholesale & retail | 2015 |
| Jacdor Investments Limited | Construction | 2014 |
| Jacek Express Transport Ltd | Transport & logistics | 2015 |
| Jackson Insurance Brokers LLP | | 2012 |
| Jacqueline Jones Limited | Extraterritorial | 2021 |
| James Brooks Snooker Club Limited | Arts & recreation | 1980 |
| James Scott Carpentry Ltd | Construction | 2023 |
| Jane Portman & Associates Ltd | Education | 2019 |
| Jass Studios Ltd | Arts & recreation | 2015 |
| JAW Group Limited | Real estate | 1998 |
| JAY Grannum LP | | 2026 |
| Jaylo's Boutique Limited | Wholesale & retail | 2011 |
| JB Properties (Cheshire) Ltd | Real estate | 2017 |
| JC Electrics & Renewables Ltd | Construction | 2024 |
| JCB Trades Ltd | Manufacturing | 2021 |
| Jcct Services Ltd | Real estate | 2023 |
| JD & Partners Ltd | Wholesale & retail | 2021 |
| JDB Electrical Contractors Ltd | Construction | 2022 |
| JDS Accountants Limited | Professional & scientific | 2024 |
| JEA Homes Limited | Real estate | 2022 |
| Jehb Consulting | Financial services | 2018 |
| Jess Albone Creations Limited | Hospitality | 2026 |
| JH Cladding Ltd | Construction | 2019 |
| Jigsaw Debt Management Ltd | Extraterritorial | 2010 |
| JIN Holdings Ltd | Real estate | 2025 |
| JJB Building Limited | Professional & scientific | 2018 |
| Jjjs Catering Ltd | Hospitality | 2025 |
| JKL Limited | Administrative & support | 1997 |
| JLB Automotive (South) Ltd | Wholesale & retail | 2024 |
| JLJ Catering Ltd | Hospitality | 2026 |
| JMC Estates Limited | Real estate | 2022 |
| JMF Accounting Limited | Professional & scientific | 2002 |
| JMT Holdings South Ltd | Financial services | 2025 |
| JOB Done Painting and Decorating Ltd | Construction | 2022 |
| John Connor Consulting Ltd | Professional & scientific | 2025 |
| John James Roofing Limited | Construction | 2006 |
| Joy Ferndown Taal Ltd | Hospitality | 2015 |
| Joyzo Limited | Information & communication | 2014 |
| Jpmh Holdings Ltd | Construction | 2021 |
| JR Construction (Dorset) Ltd | Construction | 2023 |
| JR Electrical (Dorset) Limited | Construction | 2015 |
| JR Property’S.North Limited | Real estate | 2021 |
| JSL Solutions Group Ltd | Construction | 2025 |
| JTH Consulting Ltd | Administrative & support | 2021 |
| JTM Financial Services Ltd | Financial services | 2004 |
| Juicy Shakes and Bakes Limited | Hospitality | 2018 |
| Julia's Caff Ltd | Hospitality | 2015 |
| Julian Escott Financial Services Ltd | Financial services | 2011 |
| Julias Caff Sandbanks Ltd | Hospitality | 2026 |
| Jurassic Particles Ltd | Wholesale & retail | 2025 |
| Jurassic RIB Rides Ltd | Administrative & support | 2022 |
| Justpadeluk Ltd | Information & communication | 2025 |
| K and B Installations West Moors Ltd | Construction | 2023 |
| K W S Cook Transport Limited | Transport & logistics | 2010 |
| Kaarbon Technology Ltd | Professional & scientific | 2012 |
| Kaleidoscope Design Limited | Real estate | 1997 |
| Karbowiak Holdings Ltd | Real estate | 2015 |
| Karen Miller-Ward Limited | Wholesale & retail | 2002 |
| Karsberg's Fish & Chips Ltd | Hospitality | 2012 |
| Kazys Narbutas Consulting Ltd | Professional & scientific | 2019 |
| KDC International Limited | Financial services | 2021 |
| Keen Notes Limited | Education | 2025 |
| Keith Bryant (Goldsmiths) Limited | Manufacturing | 2002 |
| Kelowna Developments Limited | Real estate | 1986 |
| KFB Consultancy Limited | Professional & scientific | 2009 |
| Kingfisher Care Limited | Wholesale & retail | 2002 |
| Kingsbury Building Ltd | Construction | 2026 |
| Kingston PTM Limited | Financial services | 2001 |
| Kinson Kebabs Limited | Hospitality | 2018 |
| Kirkham Carpentry Contractors Limited | Other services | 1996 |
| Kirkham Software Limited | Information & communication | 2019 |
| Kisacik 27 Ltd | Other services | 2025 |
| Kitchen Transformations & Design Limited | Construction | 2003 |
| KJC Catering Ltd | Hospitality | 2024 |
| KMT Management Services Limited | Professional & scientific | 2018 |
| KMW Consultants Limited | Professional & scientific | 2022 |
| Kris Nilsson Craft Limited | Manufacturing | 2016 |
| KS Media Limited | Professional & scientific | 2015 |
| Kushti BOK | Health & social care | 2009 |
| Kyra's Pet Services Ltd | Other services | 2024 |