| Interface Devices Ltd | Information & communication | 1984 |
| Interface Manufacturing Limited | Manufacturing | 1999 |
| Interface Meteovue Limited | Extraterritorial | 2003 |
| Interface Precision Engineering Limited | Manufacturing | 2011 |
| Interface Sheet Metal & Paint Limited | Manufacturing | 2002 |
| Ionut Alex Ltd | Transport & logistics | 2019 |
| Ipgi Limited | Transport & logistics | 2015 |
| Irend Limited | Construction | 2015 |
| Ironlatch Estates Limited | Construction | 2023 |
| IT Assist UK Ltd | Information & communication | 2026 |
| IT Education Hastings Limited | Information & communication | 2025 |
| J G Nutley Limited | Information & communication | 2013 |
| J R Property Limited | Real estate | 2000 |
| J Sinclair Plumbing and Heating Limited | Construction | 2023 |
| J&A FRONT2BACK Ltd | Administrative & support | 2025 |
| J&D Southern Property 2 Ltd | Real estate | 2024 |
| J&D Southern Property Ltd | Real estate | 2021 |
| J&S Homes South East Ltd | Real estate | 2026 |
| J&Y Limited | Health & social care | 2012 |
| J1EPC. Limited | Professional & scientific | 2020 |
| JAH Property Group Ltd | Real estate | 2025 |
| JAH Services Group Limited | Construction | 2025 |
| JAI Shiri Krishna Limited | Hospitality | 2023 |
| James DE RIN Management Ltd | Information & communication | 2021 |
| Jamie Mccormick Hair Ltd | Other services | 2018 |
| Jarrett Costing Services Ltd | Professional & scientific | 2008 |
| Jarvie Holdings Limited | Hospitality | 2017 |
| Jasmine Way RTM Company Limited | Households | 2008 |
| JAW Dropping Ltd | Professional & scientific | 2020 |
| JAY Properties Ltd | Real estate | 2024 |
| JB Estates (FH) Limited | Households | 2025 |
| JCM Plant Services Ltd | Construction | 2024 |
| JD Hub Ltd | Information & communication | 2023 |
| Jeffery Cloakroom Ltd | Wholesale & retail | 2025 |
| Jelen Ltd | Hospitality | 2014 |
| Jerk & Bean Afro-Caribbean Restaurant Ltd | Hospitality | 2026 |
| Jibsfromrisk Limited | Wholesale & retail | 2026 |
| Jireh a K Jones Ltd | Health & social care | 2021 |
| JJ Venturist Limited | Wholesale & retail | 2023 |
| JJB Living Ltd | Real estate | 2026 |
| JJD Home Healthcheck Limited | Construction | 2014 |
| JLH Entertainment Limited | Hospitality | 2021 |
| Jlwebb Ltd | Hospitality | 2023 |
| JOE Joes Chicken & Ribs Ltd | Hospitality | 2020 |
| John Reynolds Ltd | Professional & scientific | 2003 |
| Johnnys Daily Mart Ltd | Wholesale & retail | 2025 |
| Joint Connection Ltd | Wholesale & retail | 2024 |
| Joji Skin Care Limited | Manufacturing | 2016 |
| JRJ Property Investments Ltd | Real estate | 2023 |
| JRM Merchandising Limited | Wholesale & retail | 2014 |
| JRM Promotions Limited | Professional & scientific | 2014 |
| JRM Racing Ltd | Arts & recreation | 2010 |
| Jsbt Property Limited | Real estate | 2013 |
| JSP Optometry Ltd | Health & social care | 2021 |
| Juegos DE Sueños Limited | Information & communication | 2024 |
| Just Josh Media Ltd | Information & communication | 2025 |
| Just Studios Limited | Information & communication | 2023 |
| JV Property Hub Limited | Real estate | 2021 |
| JW Rail Services Limited | Professional & scientific | 2019 |
| K & D International (UK) Limited | Education | 2003 |
| K and S 52 Limited | Health & social care | 2007 |
| K J Butchers Guevara Limited | Financial services | 2014 |
| K Sales Limited | Wholesale & retail | 2021 |
| K&E Medical Ltd | Health & social care | 2025 |
| K&M Angells 8 Ltd | Construction | 2024 |
| K-Aia Technical Solutions Ltd | Information & communication | 2026 |
| K.T.A.D Taxi Ltd | Transport & logistics | 2026 |
| K2 Refrigeration Ltd | Hospitality | 2023 |
| Kalo Property Group Ltd | Real estate | 2023 |
| Katail Services Ltd | Health & social care | 2022 |
| Kenrith Court RTM Company Ltd | Households | 2006 |
| Kept for Life Limited | Wholesale & retail | 2021 |
| Ketsuboshi Ltd | Information & communication | 2025 |
| Khadija Investments Ltd | Real estate | 2021 |
| Khalids Kitchen Ltd | Hospitality | 2021 |
| KIA Davies Ltd | Wholesale & retail | 2025 |
| Kidman Electrical Ltd | Construction | 2019 |
| Kiisa Ltd | Information & communication | 2019 |
| Kilmur Ventures Ltd | Professional & scientific | 2025 |
| Kind Hearts Support Service Ltd | Health & social care | 2025 |
| Kinect Digital Ltd | Information & communication | 2021 |
| Kingdom Futures Limited | Financial services | 2013 |
| Kings Healthcare Advisors Limited | Administrative & support | 2025 |
| Kings Valley Pictures Limited | Information & communication | 2021 |
| Kinmount Consulting Limited | Professional & scientific | 2015 |
| Kinsau House Limited | Households | 2021 |
| Kipling County Carriage Driving Group RDA | Health & social care | 2009 |
| KLS Global Ltd | Information & communication | 2014 |
| KM Event Management Limited | Administrative & support | 2015 |
| Knight & Davey Ltd | Administrative & support | 2018 |
| Knight Accountants Limited | Professional & scientific | 2006 |
| Knight Invest LLP | | 2016 |
| Koar-Ip Solutions Ltd | Information & communication | 2025 |
| Koenders Wealth Management Ltd | Financial services | 2018 |
| Kstarr Consultancy Ltd | Professional & scientific | 2023 |
| Kurt J. Lesker Company Limited | Manufacturing | 1989 |
| L & J Data Solutions Ltd | Information & communication | 2022 |
| L & J Property Lettings Limited | Real estate | 2021 |
| L a Charles Contracts Ltd | Construction | 2008 |
| L a S Retail Limited | Wholesale & retail | 2024 |