| Jeljuxon Limited | Professional & scientific | 2015 |
| Jeljuxon Management LLP | | 2021 |
| Jeljuxon Properties Ltd | Real estate | 2025 |
| JEN Projects Ltd | Construction | 2025 |
| Jezards Limited | Construction | 2004 |
| JGA Sounds Limited | Information & communication | 2007 |
| JGB Training Limited | Professional & scientific | 2008 |
| JIB Limited | Other services | 1990 |
| JIM and Jakes Services Ltd | Water & waste | 2025 |
| JJ Mason UK Ltd | Information & communication | 2026 |
| Jjgaplumbing&Heating Ltd | Construction | 2026 |
| JKW Digital Health Consulting Ltd | Information & communication | 2023 |
| JLJ Legal Limited | Professional & scientific | 2018 |
| Jmproperties(Uk) Ltd | Real estate | 2022 |
| John Taylor Projects Ltd | Professional & scientific | 2014 |
| Johnson O'Neill Limited | Hospitality | 2025 |
| Jones and Miles Ltd | Real estate | 2024 |
| Jones Construct Limited | Construction | 2023 |
| Jonesea Ltd | Other services | 2020 |
| Joseph Azagury (London) Limited | Wholesale & retail | 2002 |
| Joseph Azagury Limited | Extraterritorial | 2005 |
| Joston Services Ltd | Administrative & support | 2011 |
| Jpec Lofts Limited | Construction | 2024 |
| JR Car Spares Limited | Wholesale & retail | 2007 |
| JRC Innovation Limited | Wholesale & retail | 2011 |
| JSC Construction Services Ltd | Construction | 2023 |
| JSM Technology Solutions Limited | Information & communication | 2018 |
| Jubell Properties Limited | Real estate | 2024 |
| Julie Drummond Consultancy Services Ltd | Administrative & support | 2024 |
| Just K Engineering Ltd | Construction | 2013 |
| Justeng Limited | Administrative & support | 2015 |
| JWO Lift Services Limited | Construction | 2015 |
| JYM Freaks Limited | Wholesale & retail | 2019 |
| Jymsym Limited | Administrative & support | 1999 |
| K Fawcett Ltd | Professional & scientific | 2026 |
| K J Carpentry & SON Limited | Construction | 2016 |
| K P S Investments Ltd | Wholesale & retail | 1996 |
| K-Dog Creative Limited | Arts & recreation | 2013 |
| Kamau Investment Ltd | Real estate | 2018 |
| Kaptur Software Ltd | Information & communication | 2023 |
| Karahan Property Ltd | Real estate | 2020 |
| Karatas Properties Group Ltd | Real estate | 2021 |
| Karpick Ltd | Construction | 2021 |
| Kars Group Ltd | Information & communication | 2023 |
| Katie Evans Limited | Other services | 2012 |
| KAY Liberty Limited | Administrative & support | 2019 |
| KAY Zenith Limited | Administrative & support | 2024 |
| Kaya Care and Supported Living CIC | Administrative & support | 2024 |
| Kaylou-Weezy Limited | Professional & scientific | 2015 |
| KBM Electrical Engineering Ltd | Professional & scientific | 2014 |
| KC Assist Limited | Professional & scientific | 2018 |
| Keenfold Limited | | 1978 |
| Keigen Ltd | Energy | 2019 |
| Keirankai Carpentry Ltd | Manufacturing | 2019 |
| Keith Penton Limited | Extraterritorial | 2011 |
| Keletech Limited | Information & communication | 2011 |
| Keliso Holdings Limited | Financial services | 2026 |
| Kelwood Contracts Ltd | Construction | 2021 |
| Kemseg Consulting Ltd | Information & communication | 2006 |
| Kenmore Sloane Recruit Ltd | Administrative & support | 2019 |
| Kent Artificial Grass Limited | Administrative & support | 2016 |
| Kent Coast Properties Limited | Real estate | 2024 |
| Kent Construct Ltd | Construction | 2025 |
| Kent New Build Windows Ltd | Construction | 2021 |
| Kent Porsche Specialist Ltd | Wholesale & retail | 2013 |
| Kent Property Management Ltd | Real estate | 2024 |
| Kent Van Centre Ltd | Wholesale & retail | 2025 |
| Kentish Building Projects Management Limited | Construction | 2017 |
| Kentish Property Services Limited | Construction | 2017 |
| Kentmobilecatering Limited | Hospitality | 2022 |
| Kerr's Ground Services Ltd | Administrative & support | 2025 |
| Keyaim Recruitment Limited | Administrative & support | 2022 |
| Keycraft Auto Locksmiths Limited | Professional & scientific | 2021 |
| KG Coffee Beans Limited | Wholesale & retail | 2017 |
| KG Stores Nine Ltd | Wholesale & retail | 2025 |
| Khainos Homes Limited | Real estate | 2025 |
| KHP Country Ltd | Extraterritorial | 2012 |
| KHP Lettings Ltd | Real estate | 2023 |
| KHP Residential Ltd | Extraterritorial | 2012 |
| Kian Medics Limited | Health & social care | 2022 |
| KIH Services Limited | Financial services | 2015 |
| Kikishines Jilbaabs & Abayas Ltd | Wholesale & retail | 2022 |
| Kimber-Allen UK Limited | Manufacturing | 2005 |
| Kings Hill Properties (South East) Ltd | Real estate | 2007 |
| Kingsnorth Court Residents Association (1987) Limited | Households | 1987 |
| Kingswood Project Management Limited | Construction | 2007 |
| Kith & KIN Training Ltd | Health & social care | 2013 |
| KJ Business Group Ltd | Construction | 2024 |
| Kj&S Ltd | Hospitality | 2015 |
| KJS Asset Management Ltd | Manufacturing | 2022 |
| Kkidz Media Limited | Information & communication | 2010 |
| KLR Occupational Therapy Limited | Health & social care | 2017 |
| KM Collective Limited | Real estate | 2026 |
| KM Developments South East Limited | Real estate | 2026 |
| KMD GAS Installations Ltd | Construction | 2011 |
| Kmgfencing Ltd | Administrative & support | 2025 |
| KO Electrical Services Ltd | Construction | 2026 |
| KOI Carp UK Limited | Wholesale & retail | 2008 |
| Kompleet Limited | Administrative & support | 2021 |
| Kovai Holdings Limited | Information & communication | 2021 |