| J & R Bucher | | 1996 |
| J & S Grimmer Builders Limited | Construction | 2007 |
| J G Wang & Co. Ltd | Professional & scientific | 2009 |
| J Presley Restoration Ltd | Construction | 2008 |
| J R L Scaffolding Limited | Construction | 2003 |
| J. & J. Howlett (Garage) Limited | Real estate | 1979 |
| J. Briggs Builders Limited | Construction | 2007 |
| J.C.S.Hi-Torque Limited | Manufacturing | 1964 |
| J.E.B. Technologies Limited | Manufacturing | 1972 |
| J.S.T. (U.K.) Limited | Manufacturing | 1982 |
| J.Smallridge & Co Limited | Health & social care | 2015 |
| J.T.Pegg & Sons Limited | Manufacturing | 1958 |
| J.W. Engineering (Bury ST. Edmunds) Limited | Manufacturing | 1981 |
| Jackamans Limited | Professional & scientific | 2005 |
| Jackson Civil Engineering Limited | Construction | 2007 |
| Jackson Civils Limited | Construction | 2003 |
| Jackson Frameworks Limited | Extraterritorial | 2003 |
| Jaik Properties Limited | Real estate | 2019 |
| Jaina Parmar Consulting Ltd | Information & communication | 2022 |
| Jalto Limited | Professional & scientific | 2023 |
| James Electrical Ltd | Construction | 2007 |
| James Hogg Estate Agents Limited | Professional & scientific | 2007 |
| Jasmine Enterprise Software Services Ltd | Information & communication | 2007 |
| Jason Finch Limited | Manufacturing | 2002 |
| Jayrest Interiors Limited | Manufacturing | 2002 |
| JC Print and Packaging Ltd | Administrative & support | 2026 |
| JCA Online Ltd | Other services | 2004 |
| Jemstone Home Solutions Ltd | Transport & logistics | 2026 |
| Jenna Hall Counselling Ltd | Other services | 2020 |
| Jeremy Ladd Plumbing & Heating Services Limited | Construction | 2006 |
| Jetset Dreams Limited | Information & communication | 2022 |
| JHR Decorators Ltd | Construction | 2026 |
| JIM Rankin Engineering Services Limited | Professional & scientific | 1998 |
| JIO Avanzado Limited | Arts & recreation | 2023 |
| Jj's Watches and Antiques Ltd | Wholesale & retail | 1989 |
| JKM Property Ltd | Real estate | 2021 |
| JKS Holistic Living Ltd | Health & social care | 2025 |
| JMJ Financial Limited | Arts & recreation | 2002 |
| JNY Software Ltd | Information & communication | 2026 |
| JOE Harmonics Ltd | Manufacturing | 2025 |
| John Danby Racing Limited | Manufacturing | 2002 |
| John David Barber Ltd | Wholesale & retail | 2024 |
| John Hutchings Services Limited | Administrative & support | 2002 |
| John Oakes & Partners | | 1987 |
| John Skelly (Fish) Limited | Wholesale & retail | 2003 |
| John Sturman Construction Limited | Construction | 2005 |
| John W Younger Limited | Construction | 2008 |
| John, Hilary & Co. (Holdings) Limited | Professional & scientific | 1987 |
| John,Hilary & Co.(Insurance)Limited | Financial services | 1965 |
| Jolo Stays Ltd | Real estate | 2024 |
| JP Chick & Partners Limited | Professional & scientific | 2003 |
| JS Carpentry & Construction Ltd | Manufacturing | 2020 |
| Julie & Co Homes Limited | Real estate | 2023 |
| Just Dify Ltd | Other services | 2019 |
| K Artus Holdings Ltd | Financial services | 2024 |
| K Button Limited | Manufacturing | 2005 |
| K C Heating Limited | Construction | 2004 |
| K Dossett Limited | Construction | 2003 |
| K M Mckenzie Book-Keeping Services Limited | Professional & scientific | 2003 |
| K.C. Paving & Construction Ltd | Construction | 2017 |
| K.W. Franks Shipping Limited | | 1984 |
| K108 Ventures Limited | Professional & scientific | 2023 |
| Kagitals Technologies Limited | Professional & scientific | 2025 |
| Kaizen Bonsai Limited | Wholesale & retail | 2006 |
| Kaly Limited | Wholesale & retail | 2024 |
| Kalyan Properties Ltd | Real estate | 2023 |
| Kanto Media Ltd | Information & communication | 2017 |
| Karar Burgers Ltd | Hospitality | 2023 |
| Karma Curry Ltd | Manufacturing | 2022 |
| Kaska Group Ltd | Financial services | 2026 |
| Kaska Investments Ltd | Financial services | 2026 |
| Kaska Properties Ltd | Real estate | 2026 |
| Kays Fruit VEG and Florist Ltd | Wholesale & retail | 1996 |
| KBC Education Ltd | Education | 2024 |
| Kbda Associates Limited | Information & communication | 2025 |
| KC Property & Rentals Ltd | Real estate | 2024 |
| KC Property Partners Ltd | Real estate | 2023 |
| Keane Property Ltd | Real estate | 2024 |
| Keebee Optical Ltd | Health & social care | 2023 |
| Keep Calm SRL Ltd | Information & communication | 2025 |
| Keith White Limited | Wholesale & retail | 2004 |
| Kelaya Living Ltd | Wholesale & retail | 2019 |
| Kelly Creates Limited | Wholesale & retail | 2025 |
| KEN Grime & SON Limited | Construction | 2002 |
| Kenworth Associates Europe Limited | Financial services | 1999 |
| Kerseys Limited | Professional & scientific | 1995 |
| Keslerlab Ltd | Wholesale & retail | 2025 |
| Kessingland Garage and MOT Centre Limited | Wholesale & retail | 2003 |
| Kestra Group Ltd | Construction | 2022 |
| Key to Your Stay Ltd | Extraterritorial | 2023 |
| Keyways the Locksmiths Limited | Wholesale & retail | 2000 |
| Kibbles Mill Ltd | Wholesale & retail | 2012 |
| Kieo Studio Limited | Information & communication | 2022 |
| Kimera Group Limited | Professional & scientific | 2024 |
| Kimera Property Limited | Real estate | 2025 |
| Kinflaredecor Ltd | Wholesale & retail | 2026 |
| Kingdom Bridge Investments Ltd | Real estate | 2024 |
| Kintok Limited | Professional & scientific | 1999 |
| Kitchencraft Studios Limited | | 1981 |
| Kite Opticians Limited | Health & social care | 2003 |