| Jibjab Associates Ltd | Real estate | 2013 |
| Jibjab Capital Limited | Real estate | 2003 |
| JJ Surveying Limited | Professional & scientific | 2009 |
| JK Structure Limited | Wholesale & retail | 2000 |
| Jkiwl Consulting Ltd | Professional & scientific | 2026 |
| JM Gilchrist Consultancy Ltd | Professional & scientific | 2019 |
| Joamella LLP | | 2024 |
| Joeman Technical Services Limited | Construction | 2013 |
| John Aldridge Consultancy Ltd | Professional & scientific | 2019 |
| John Hannant Plumbing and Engineering Services Ltd | Construction | 2005 |
| John Huntley (Petersfield) Limited | Wholesale & retail | 1996 |
| John Jenkins & Sons Limited | Wholesale & retail | 1956 |
| John Sheaff Limited | Professional & scientific | 2002 |
| Jonathan Frye's Plumbing and Heating Ltd | Construction | 2024 |
| Jones & Young Limited | Financial services | 2021 |
| Jouknow Limited | Professional & scientific | 2025 |
| JS Hospitality Ltd | Hospitality | 2023 |
| JTG Limited | Households | 2022 |
| Judge Inc Limited | Information & communication | 2025 |
| Juiced Apps Ltd | Information & communication | 2026 |
| Julia Newton Consultancy Limited | Public administration | 2024 |
| Jumelia Ltd | Professional & scientific | 2014 |
| Juno Development Group Ltd | Construction | 2022 |
| Jupiter Fitting Services Ltd | Construction | 2026 |
| Just About Managing Limited | Professional & scientific | 2003 |
| JW Workspace Limited | Administrative & support | 2016 |
| K G C Construction Ltd | Construction | 2014 |
| K.E. Page Limited | Administrative & support | 1974 |
| KAJ Forbes Consulting Limited | Professional & scientific | 2023 |
| Kaluma Travel Limited | Hospitality | 2003 |
| KAT Kirsty Armstrong Training Limited | Professional & scientific | 2016 |
| Kate Forman Designs Limited | Wholesale & retail | 2002 |
| Kate Maria Languages Ltd | Education | 2020 |
| Kate Tarry Ltd | Professional & scientific | 2021 |
| Katewatson Limited | Other services | 2018 |
| Kathryn Page Interiors Ltd | Wholesale & retail | 2018 |
| Kati Whitaker Productions Ltd | Information & communication | 2014 |
| Keeler Productions Limited | Information & communication | 2018 |
| Kemloc Developments Ltd | Construction | 2011 |
| Kent Capital Finance Ltd | Financial services | 2024 |
| Kestrel Construction Services Ltd | Construction | 1997 |
| Kettlebrook Construction Limited | Construction | 2013 |
| KEW Computers (Holdings) Limited | Professional & scientific | 1998 |
| KEW Computers Limited | Information & communication | 1998 |
| Kewvisum Limited | Information & communication | 2014 |
| Kiklo Spaces Limited | Transport & logistics | 2020 |
| Kingspan Light + Air (UK & Ireland) Limited | Construction | 1994 |
| Kingswell Asset Group Ltd | Wholesale & retail | 2025 |
| Kirby Solway Limited | Administrative & support | 2004 |
| Kistebena Ltd | Professional & scientific | 2026 |
| Kitchen and Bathroom Solutions Ltd | Construction | 2018 |
| Kittermaster Consultancy Limited | Professional & scientific | 2003 |
| KJC Business Consultancy Limited | Information & communication | 2016 |
| Knowmad Limited | Information & communication | 2020 |
| Knox-Crawford Corporation Limited | Other services | 1989 |
| Koala Systems Limited | Information & communication | 1994 |
| Kopays Limited | Information & communication | 2022 |
| Koru Property Lettings Limited | Real estate | 2018 |
| Kosmos Recruitment Limited | Administrative & support | 2014 |
| KR1 a Ltd | Construction | 2025 |
| KR1 Investments Ltd | Real estate | 2018 |
| Kryptonite Storage Limited | Transport & logistics | 2018 |
| KT & Partners Ltd | Professional & scientific | 2012 |
| Kubopay Limited | Financial services | 2018 |
| KVM Create Limited | Manufacturing | 2022 |
| Kynance QS Services Limited | Professional & scientific | 2022 |
| Kyrix Ltd | Professional & scientific | 2025 |
| L Audsley Roofing Ltd | Construction | 2016 |
| L&K Nails Ltd | Other services | 2025 |
| L'Organiq Ltd | Manufacturing | 2019 |
| LA Ciel Ltd | Construction | 2019 |
| LA Petite Ferme Limited | Professional & scientific | 2022 |
| LA Piazzetta Ltd | Hospitality | 2007 |
| Lagain Holdings Limited | Financial services | 2025 |
| Lamb & Newt Ltd | Wholesale & retail | 2020 |
| Lambart and Browne Limited | Administrative & support | 2010 |
| Lambart and Browne Procurement Limited | Extraterritorial | 2019 |
| Lamparts Limited | Extraterritorial | 1994 |
| Landlord Academy Limited | Other services | 2020 |
| Landlord Consultants UK Limited | Real estate | 2025 |
| Langley Alexander Limited | Wholesale & retail | 2022 |
| Langrish House Limited | Hospitality | 1998 |
| Langrish Park Limited | Real estate | 2017 |
| Lanzante Automotive Ltd | Manufacturing | 2024 |
| Lanzante Holdings Limited | Financial services | 2026 |
| Lanzante Limited | Wholesale & retail | 1988 |
| Lanzante Motorsports Ltd | Extraterritorial | 2025 |
| Lanzante Properties Limited | Real estate | 2026 |
| Lanzante Service Limited | Wholesale & retail | 2020 |
| Lanzante Storage Limited | Transport & logistics | 2023 |
| Large Properties Limited | Hospitality | 2016 |
| Last Looks Facilities Ltd | Administrative & support | 2021 |
| Lavender Hill Flower Company Limited | Wholesale & retail | 2016 |
| Lawrence Assets Ltd | Real estate | 2019 |
| LDZ Designs Limited | Other services | 2016 |
| Leading Health Limited | Professional & scientific | 2016 |
| Leaflet Distribution Direct Ltd | Information & communication | 2014 |
| Leafon Ltd | Professional & scientific | 2016 |
| Lemon Computing Limited | Information & communication | 1999 |
| Lennon Films Limited | Information & communication | 2008 |