| Interflight Technical Services Limited | Manufacturing | 2013 |
| Interfurb UK Ltd | Construction | 2024 |
| International Pipe Freezing Association Limited | Extraterritorial | 1999 |
| International Surveying Network (Group) Ltd | Administrative & support | 2020 |
| Interoperability (UK) Limited | Professional & scientific | 2014 |
| Investmentleap Limited | Information & communication | 2019 |
| Invicta Military-Vehicle Preservation Society Limited | Information & communication | 2002 |
| Ionic Stonework and Restoration Ltd | Construction | 2019 |
| IP Entertainment Ltd | Professional & scientific | 2024 |
| Ipdp Properties Limited | Real estate | 2015 |
| Iprint Manage Limited | Manufacturing | 2018 |
| Isamaxi Ltd | Real estate | 2020 |
| IT Foods Limited | Hospitality | 2009 |
| IT Infrastructure Management Limited | Information & communication | 2011 |
| IT Must BE a Sign Limited | Manufacturing | 2020 |
| IT Services Project Management Limited | Information & communication | 2014 |
| IT Techs (Kent) Limited | Information & communication | 2010 |
| It's ALL About U Ltd | Other services | 2010 |
| It's Modern Sports Ltd | Arts & recreation | 2025 |
| Italian Interiors Limited | Professional & scientific | 2001 |
| J & M Developments (London) Limited | Construction | 2014 |
| J & T Accountancy Services Ltd | Professional & scientific | 2024 |
| J D H Building Services Limited | Professional & scientific | 2021 |
| J MCB Make UP Ltd | Administrative & support | 2024 |
| J Miko Logistics Limited | Construction | 2013 |
| J R Leisure Rentals Ltd | Administrative & support | 2021 |
| J R Westerham Ltd | Wholesale & retail | 2021 |
| J Wilson Projects Ltd | Construction | 2025 |
| J&B Building Contractors Limited | Construction | 2023 |
| J&T Home Care Services Ltd | Administrative & support | 2025 |
| J.Court & Sons (Norwood) Limited | Financial services | 2018 |
| J.H. Powell Limited | Administrative & support | 2003 |
| J.S. Office Environments Limited | Extraterritorial | 2007 |
| J.S. Seating Limited | Wholesale & retail | 1972 |
| J2J Holdings Limited | Financial services | 2017 |
| Jacob's Ladder Limited | Wholesale & retail | 2013 |
| Jagech Consulting Limited | Professional & scientific | 2012 |
| Jalme Property Limited | Real estate | 2020 |
| James Millard (Hildenborough) Limited | Real estate | 1999 |
| James Millard (Westerham) Limited | Real estate | 2013 |
| Jason Metals Limited | Wholesale & retail | 2019 |
| Jaxon Property Ltd | Real estate | 2021 |
| JB Bakers Ltd | Construction | 2026 |
| JB Cleaning London & Kent Limited | Administrative & support | 2025 |
| JCP Building Contractors Ltd | Construction | 2026 |
| JD Capital Solutions Ltd | Financial services | 2025 |
| JDH Autos Ltd | Wholesale & retail | 2015 |
| JDW Comms Ltd | Construction | 2023 |
| Jeanne Daubie Limited | Professional & scientific | 2019 |
| Jeevans Burgers Ltd | Hospitality | 2022 |
| Jeevs Catering Ltd | Hospitality | 2025 |
| Jeks Advisory Services Limited | Professional & scientific | 2017 |
| Jennifer Harty Ltd | Other services | 2021 |
| Jetms Completions Ltd | Manufacturing | 2008 |
| JGC Sportsturf Maintenance Ltd | Arts & recreation | 2011 |
| Jhrs Limited | Construction | 2007 |
| Jimjam Properties Ltd | Real estate | 2026 |
| JJ Wilde Cornice Ltd | Manufacturing | 2022 |
| Jj&Ma Ltd | Administrative & support | 2026 |
| JKE Vehicle Cleaning Limited | Administrative & support | 2026 |
| JL Properties Chislehurst Ltd | Real estate | 2022 |
| JL Watches Ltd | Wholesale & retail | 2022 |
| JLT Property Group Ltd | Real estate | 2023 |
| Jmatias Holdings Ltd | Administrative & support | 2023 |
| Jmbw Solutions Ltd | Information & communication | 2022 |
| Jmfc Consulting Limited | Professional & scientific | 2021 |
| Jmvdk Limited | Arts & recreation | 2022 |
| Jnav Ltd | Wholesale & retail | 2024 |
| JO Knows Food Ltd | Hospitality | 2021 |
| Joal HB Limited | Hospitality | 2026 |
| John Alan Estate Agents Limited | Real estate | 1999 |
| John Charles Holdings Ltd | Real estate | 2025 |
| John Driscoll Photography Limited | Professional & scientific | 2018 |
| Jojohnsonconsulting Ltd | Administrative & support | 2018 |
| Joro Ltd | Real estate | 2025 |
| Jose Zevallos Ltd | Administrative & support | 2026 |
| JP Hart Plumbing & Heating Limited | Construction | 2013 |
| JPI Brueton Limited | Construction | 2011 |
| JPL Integrated Solutions Ltd | Information & communication | 2016 |
| JPS Contractors Limited | Construction | 1996 |
| Jpwtransport Ltd | Transport & logistics | 2023 |
| JR BIM Solutions Ltd | Professional & scientific | 2022 |
| JRB Electrical Services Ltd | Construction | 2016 |
| JRB Electrical Solutions Ltd | Construction | 2023 |
| JSL Holdings Limited | Financial services | 2019 |
| JT Search Ltd | Administrative & support | 2026 |
| JTL Property Co Ltd | Real estate | 2022 |
| Jtspar Properties Limited | Real estate | 2025 |
| JTW Surveys Limited | Construction | 2008 |
| Jude Broadcast Ltd | Information & communication | 2024 |
| Julie Tushingham Reputation & Business Coach Ltd | Health & social care | 2020 |
| Junebry Management Ltd | Other services | 2022 |
| Jupitarise Ltd | Wholesale & retail | 2025 |
| Just Balancing the Books Ltd | Administrative & support | 2019 |
| Just Construction Recruitment Ltd | Administrative & support | 2012 |
| Just Figures Limited | Professional & scientific | 2008 |
| Just Tickittyboo Ltd | Administrative & support | 2019 |
| JWS Alloys Ltd | Wholesale & retail | 2022 |
| JWS Development & Residential Ltd | Households | 2024 |
| JWS Plumbing & Heating Services Ltd | Construction | 2019 |