| Jainam International UK Ltd | Wholesale & retail | 2022 |
| JAL Compliance Limited | Information & communication | 2016 |
| Jamal Altai Limited | Health & social care | 2010 |
| James Chaney Consulting Limited | Professional & scientific | 2026 |
| James George Investments Limited | Real estate | 2016 |
| James Kent Limited | Information & communication | 2000 |
| Jane’S Healthcare Ltd | Health & social care | 2024 |
| Jaquets Court Residents Association Limited | Administrative & support | 1965 |
| Jason Lakin Limited | Professional & scientific | 2020 |
| JAY Brooks Limited | Professional & scientific | 2001 |
| Jay's Plumbing & Heating Ltd | Construction | 2017 |
| Jaya Retail Ltd | Wholesale & retail | 2023 |
| Jayjay Creative LLP | | 2025 |
| JB Childcare Limited | Health & social care | 2026 |
| JC Building & Decorating Limited | Construction | 2017 |
| JCS Business Analytics Ltd | Professional & scientific | 2020 |
| JD Admin Solutions Limited | Administrative & support | 2014 |
| Jdpd Consultancy Limited | Financial services | 2024 |
| JDS Mortgages Limited | Professional & scientific | 2026 |
| JE Medical Associates Ltd. | Health & social care | 2018 |
| Jean-Philippe Guegan Limited | Professional & scientific | 2018 |
| JEE Property Holdings Limited | Financial services | 2021 |
| JEE Resco Limited | Real estate | 2021 |
| JEG Electrical Ltd | Construction | 2024 |
| JEM Communications Limited | Other services | 2024 |
| Jenko Scaffolding Ltd | Construction | 2021 |
| Jensicca Property Development Ltd | Real estate | 2017 |
| JFK Services BTL Limited | Real estate | 2021 |
| JIG Patel Ltd | Health & social care | 2010 |
| Jjbc Limited | Professional & scientific | 2021 |
| JJP Double Glazing Ltd | Construction | 2023 |
| Jkaoa Ltd | Wholesale & retail | 2022 |
| JLG Decor Ltd | Construction | 2025 |
| JM Direct Ltd | Wholesale & retail | 2024 |
| JMF Badminton Academy Ltd | Education | 2022 |
| JMH CAD Design Limited | Information & communication | 2014 |
| Jmpa Management Ltd | Construction | 2024 |
| Jmuzik Records Ltd | Information & communication | 2022 |
| JND Design Studio Ltd | Professional & scientific | 2025 |
| Joanjoan Ltd | Information & communication | 2018 |
| Jocksteene Holdings Ltd | Real estate | 2026 |
| Jocular Services Limited | Professional & scientific | 2023 |
| Joel Worsley Construction Ltd | Construction | 2023 |
| John Chappell Limited | Construction | 2013 |
| John Roney Taxi Services Limited | Transport & logistics | 2013 |
| Jolly's Limited | Other services | 2019 |
| Joma Media Ltd | Arts & recreation | 2014 |
| Joma Productions Ltd | Arts & recreation | 2014 |
| Jonathan Payne Consulting Limited | Professional & scientific | 2022 |
| Jones Mckee Limited | Professional & scientific | 2021 |
| Jordan Rogers Ltd | Other services | 2025 |
| Joseph Bespoke Interiors Ltd | Construction | 2020 |
| Joy Designs Ltd. | Other services | 2000 |
| Joy Zarine Ltd | Administrative & support | 2015 |
| Joyful Star Day Nursery Ltd | Education | 2015 |
| JRM Systems Limited | Administrative & support | 2014 |
| JS Capital Holdings Limited | Real estate | 2026 |
| JSG Enterprises Limited | Financial services | 2002 |
| JSK Partitions Ltd | Construction | 2020 |
| JTG Heating Company Limited | Construction | 2026 |
| Jubilee Way Residents Association Limited | Households | 1985 |
| Just Fascias (S.E.) Ltd | Construction | 2011 |
| Just Scaffolding Ltd | Construction | 2019 |
| Just Simple DR Ltd | Real estate | 2021 |
| JW Lighting Ltd | Construction | 2014 |
| JW Pipe Services Limited | Construction | 2017 |
| JWC Electrical Solutions Ltd | Construction | 2016 |
| K E Wells Solutions Ltd | Information & communication | 2026 |
| K-Crab Services Ltd | Professional & scientific | 2019 |
| K. J. Heating & Plumbing Limited | Construction | 2008 |
| K.L. Harvey Project Management Limited | Administrative & support | 2016 |
| K2 Horizons Limited | Real estate | 2026 |
| K3 (YKA) Investments Limited | Real estate | 2025 |
| Kaaa Construction Ltd | Construction | 2025 |
| Kadambas Limited | Information & communication | 2018 |
| Kaleidoscope International Emea Ltd | Professional & scientific | 2025 |
| Kals Investments Limited Partnership | | 2009 |
| Kamko Electrical Ltd | Construction | 2015 |
| Katson Haven Properties Limited | Real estate | 2025 |
| Kays Modeling Agency Commercial Advertising Limited | Hospitality | 2025 |
| KBG Digital Ltd | Information & communication | 2025 |
| KC Event Hire Ltd | Administrative & support | 2023 |
| KCM Events and Conferences Ltd | Administrative & support | 2025 |
| Kdan Homes Ltd | Real estate | 2023 |
| KDS Medicare Limited | Wholesale & retail | 2004 |
| Keane Electrical (Kent) Ltd | Construction | 2013 |
| Keane Electrical Nationwide Ltd | Construction | 2018 |
| Keith R. Gough Limited | Financial services | 2003 |
| Kekou Events Ltd | Hospitality | 2024 |
| Kent Electrical Installations Ltd | Construction | 2009 |
| Kent Heating & GAS Services Limited | Construction | 2019 |
| Kent Maintenance & Building Services Ltd | Construction | 2021 |
| Kent Microbars Ltd | Hospitality | 2024 |
| Kent Ventilation Ltd | Construction | 2015 |
| Kentec Draughting Services Limited | Construction | 1991 |
| Kentish Stone Ltd | Construction | 2014 |
| Kents Refurbishments Limited | Other services | 2014 |
| Kepal Engineering Limited | Professional & scientific | 2024 |
| Kev's Ices Limited | Hospitality | 2025 |
| Keycharge Limited | Real estate | 1995 |