| JOB Accomm Limited | Administrative & support | 2019 |
| JOE Baker Consultancy Limited | Professional & scientific | 2012 |
| John C Hunter & Co Limited | Professional & scientific | 2012 |
| John Ross & SON Limited | Wholesale & retail | 2002 |
| John Rush Services Limited | Administrative & support | 2007 |
| Johnsco Limited | Professional & scientific | 2006 |
| Johnson Logistics Ltd | Real estate | 2012 |
| Jolt Media Limited | Extraterritorial | 2018 |
| Jonathan Charles Bespoke Limited | Manufacturing | 2024 |
| Jones Boatyard Ltd | Manufacturing | 1970 |
| Jonney Gates Limited | Administrative & support | 2010 |
| Jordan H Real Estate Ltd | Real estate | 2023 |
| JP Building Ltd | Construction | 2020 |
| JPH Steelworks (Holdings) Limited | Financial services | 2024 |
| JPH Steelworks Limited | Manufacturing | 2005 |
| JPK Cattran Limited | Financial services | 2013 |
| JS Law Limited | Professional & scientific | 2002 |
| JSL Legal Services Limited | Professional & scientific | 2005 |
| JSP (Charlwood) Limited | Real estate | 2018 |
| JSP 64BR Limited | Real estate | 2025 |
| JSP DRY Cleaning & Laundry Limited | Other services | 2015 |
| JSP Streatham Limited | Real estate | 2025 |
| JSP Supplies Limited | Wholesale & retail | 2021 |
| JSP Topco Limited | Financial services | 2025 |
| JSP Witney Limited | Real estate | 2025 |
| JTC Residential Ltd | Households | 2023 |
| JTC Roofing & Cladding Limited | Construction | 2023 |
| Juno Organics Limited | Other services | 2018 |
| Jupiter Workshops Property UK Ltd | Financial services | 2024 |
| JUS Desserts (ST Ives) Ltd | Wholesale & retail | 2003 |
| Just SO Property Limited | Real estate | 2011 |
| JWB International Search Limited | Administrative & support | 2013 |
| JWH Developments Limited | Construction | 2026 |
| K & M Lighting Services Limited | Manufacturing | 2011 |
| K & T Chapman Driving Services Ltd | Transport & logistics | 2017 |
| K and M Bespoke Ltd | Manufacturing | 2024 |
| K B H Investments Limited | Real estate | 2022 |
| K D Hair Design Limited | Other services | 2014 |
| K K Barbershop Ltd | Other services | 2023 |
| K Lugg Consultancy Limited | Professional & scientific | 2023 |
| K&N Smart Technologies Ltd | Wholesale & retail | 2025 |
| K.R.C.Quality Rubber Mouldings Limited | Professional & scientific | 1967 |
| KA Taxis Ltd | Transport & logistics | 2025 |
| Kace Consulting Ltd | Construction | 2025 |
| Kade Nova Limited | Real estate | 2026 |
| Kade Vertex Limited | Construction | 2026 |
| Kadiriler Ltd | Hospitality | 2024 |
| Kaleidocart Limited | Wholesale & retail | 2025 |
| Kankar Limited | Hospitality | 2012 |
| Kappa Projects Ltd | Construction | 2025 |
| Kappa Ventures Limited | Manufacturing | 2022 |
| Karda Interiors & Facades Ltd | Construction | 2018 |
| Karen Wardley Limited | Financial services | 2019 |
| Karenza Court Residents Limited | Households | 1998 |
| Katy Poore Estate Agents Ltd | Real estate | 2024 |
| Keebunga Company Limited | Wholesale & retail | 2009 |
| Keepsafe Security (UK) Limited | Administrative & support | 1994 |
| Keepsafe Security Limited | Professional & scientific | 2004 |
| Kernow Self Drive Boats Ltd | Administrative & support | 2015 |
| Kerry Arnold Property Search Ltd | Real estate | 2020 |
| Key Change Ltd | Arts & recreation | 2025 |
| Key Financial Wealth Management Ltd | Financial services | 2010 |
| Keyhole Property Group Ltd | Real estate | 2026 |
| KF Flat Roofing Ltd | Construction | 2025 |
| KFP Consulting Limited | Professional & scientific | 2021 |
| Kfwm Holdings Limited | Financial services | 2019 |
| Khaani Takeaway Limited | Hospitality | 2025 |
| Kiddles Coaches Ltd | Transport & logistics | 2003 |
| Kimber and Kimber Ltd | Professional & scientific | 2026 |
| KIN Collective Recruitment Ltd | Administrative & support | 2024 |
| King Alfred (Sports) Limited | Other services | 1975 |
| Kingra Fleetcare Services Limited | Wholesale & retail | 2025 |
| Kingra Properties Limited | Real estate | 2024 |
| Kingscal Roofing Ltd | Construction | 2016 |
| Kingston Projects Limited | Construction | 2019 |
| Kirt Ltd | Professional & scientific | 2017 |
| Klemetric Displays Limited | Wholesale & retail | 1971 |
| Klink Productions Limited | Arts & recreation | 2014 |
| KM PM by Kandm Bespoke Limited | Information & communication | 2025 |
| Konnect Logistics Services Limited | Transport & logistics | 2022 |
| Koparion Limited | Financial services | 2020 |
| Kor.Deli Ltd | Hospitality | 2021 |
| Korten Limited | Construction | 1964 |
| KPM Carpentry & Build Ltd | Construction | 2021 |
| KPR Property Management Services Ltd | Real estate | 2015 |
| Kro.No Pictures Ltd | Information & communication | 2014 |
| Kulinarium Limited | Hospitality | 2024 |
| L Falkner Ltd | Wholesale & retail | 2022 |
| L&M Maintenance Ltd | Manufacturing | 2026 |
| L. a. Searle Estates Ltd | Real estate | 2026 |
| Lakeland Brewing Company Limited | Administrative & support | 2003 |
| Lakeside Medical Supplies Ltd | Health & social care | 2025 |
| Lancaster Lounge Ltd | Wholesale & retail | 2023 |
| Lancaster Property Developments Ltd | Real estate | 2026 |
| Lanmark Associates Ltd | Professional & scientific | 2017 |
| Lark Arts Ltd | Arts & recreation | 2023 |
| Laserstead Limited | Other services | 2013 |
| Lastic Consulting Limited | Information & communication | 1991 |
| Lawton Engineering Limited | Professional & scientific | 2025 |
| LDM Build Ltd | Construction | 2020 |