| Isle of Wight Fuels Limited | Wholesale & retail | 2012 |
| Isolux Limited | Manufacturing | 2007 |
| Istore Inc Ltd | Other services | 2012 |
| IT MAX Limited | Information & communication | 2004 |
| Italian Premises Limited | Real estate | 2002 |
| Itop Limited | Information & communication | 2006 |
| Iucn Coin Ltd | Agriculture & fishing | 2022 |
| IVY House Residents Association Limited | Administrative & support | 1976 |
| Ivydrive Holdings Ltd | Construction | 1984 |
| Izzy UK Limited | Construction | 2001 |
| J & L Building & Maintenance Contracts Limited | Construction | 2007 |
| J & L Scaffolding Limited | Construction | 2000 |
| J & W Properties Limited Liability Partnership | | 2004 |
| J C Investments Ltd | Real estate | 1998 |
| J Duncombe Limited | Construction | 2003 |
| J Lewis (Auto Electrical) Limited | Wholesale & retail | 2005 |
| J P B Leisure Limited | Hospitality | 1991 |
| J R Roofing Limited | Construction | 2004 |
| J Sapphirah Limited | Wholesale & retail | 2003 |
| J. & M. Nixon Printers Limited | Manufacturing | 1975 |
| J. Dixon Associates Ltd. | Professional & scientific | 2004 |
| J. R. Homecare Limited | Wholesale & retail | 1979 |
| J.A. & A.Property Investments Limited | Real estate | 1959 |
| J.K (Vehicle Hire) Limited | Manufacturing | 2005 |
| J.Murphy Developments Limited | Construction | 2002 |
| J.W. Walker & Sons Limited | Manufacturing | 1972 |
| Jabss Utilities Limited | Administrative & support | 2024 |
| Jackman Enterprises Limited | Construction | 1998 |
| Jagmar Enterprise Ltd | Real estate | 2023 |
| Jaldi Technology Ltd | Information & communication | 2021 |
| James Murray Lettings Limited | Real estate | 2024 |
| James Saynor Ltd | Information & communication | 2002 |
| James Strivens Electrical Limited | Construction | 2016 |
| Janelle Accounting Limited | Professional & scientific | 1995 |
| Jays Properties Limited | Construction | 1975 |
| Jazdc Limited | Information & communication | 2003 |
| JCJ Accounting Services Limited | Professional & scientific | 2007 |
| Jermellnithonealtarverstore Ltd | Wholesale & retail | 2025 |
| Jersey Landscapes Limited | Other services | 2003 |
| Jessica Cosmetics International Limited | Professional & scientific | 1992 |
| JET Boot Labs Limited | Information & communication | 2004 |
| JF SUB Ltd | Hospitality | 2019 |
| Jfb-Fiza LLP | | 2022 |
| Jitterbug Coffee Co Ltd | Hospitality | 2023 |
| JK Groundwork Services Limited | Construction | 2021 |
| JK Specs Ltd | Wholesale & retail | 2017 |
| Jkmarbay Ltd | Manufacturing | 2021 |
| JKR Engineering Ltd | Construction | 2021 |
| JKS Contracts Limited | Construction | 2007 |
| JL Fruit Limited | Wholesale & retail | 2008 |
| Jmcs Engineering Ltd | Professional & scientific | 2021 |
| JMT Designs Limited | Arts & recreation | 2003 |
| John Archer Limited | Information & communication | 2004 |
| John Connor GAS Services Limited | Construction | 2003 |
| John DIX Consulting Ltd | Professional & scientific | 2004 |
| John FOY Limited | Wholesale & retail | 2003 |
| John Galvin Ltd | Professional & scientific | 2002 |
| John Gladstone of London Limited | Extraterritorial | 2006 |
| John H James (International) Limited | | 1986 |
| John Keen (Tring Transport) Limited | Construction | 1975 |
| John Mcgovern Construction Limited | Construction | 1985 |
| John Michael Properties Ltd | Real estate | 2005 |
| Johne & Reilhofer (U.K.) Limited | Professional & scientific | 1980 |
| Johnson Ellis Limited | Construction | 2007 |
| Johnsons Creative Ltd | Administrative & support | 2010 |
| Johnston and Mathers Associates Limited | Arts & recreation | 2002 |
| Joint (EOT Trustee) Limited | Financial services | 2025 |
| Jokkey Limited | Transport & logistics | 2023 |
| JON Etchells Consulting Limited | Professional & scientific | 2003 |
| Jonathan Hunt Limited | Real estate | 2003 |
| Jones & Farrow Limited | Construction | 2006 |
| Jones and Sons Environmental Sciences Limited | Professional & scientific | 2005 |
| Jonny Baba Limited | Other services | 2003 |
| Joseph Oliver Marketing Limited | Financial services | 2003 |
| Joseph Rochford Gardens Limited | Agriculture & fishing | 1974 |
| Joydesioux Ltd | Wholesale & retail | 2022 |
| JP Percussion Limited | Wholesale & retail | 2021 |
| JPL Accountants Ltd | Professional & scientific | 2007 |
| Jppm Services Limited | Professional & scientific | 2002 |
| JSH Environmental Products Ltd. | Manufacturing | 1998 |
| JTG Agencies Limited | Wholesale & retail | 2005 |
| Judgeupper Limited | Real estate | 1988 |
| Juice Research Limited | Professional & scientific | 2002 |
| Jumanji - Home, Pet & Gardening Ltd | Wholesale & retail | 2025 |
| Just Art Limited | Wholesale & retail | 1993 |
| Just Finder Ltd | Information & communication | 2023 |
| Jvtm Limited | Real estate | 2025 |
| Jvtm Property Management Co Ltd | Real estate | 2025 |
| JWF Flooring Limited | Construction | 2000 |
| K & a Productions Limited | Arts & recreation | 1995 |
| K K Electrical Limited | Construction | 2007 |
| K P Recycling Limited | Professional & scientific | 2006 |
| K V B Architects Limited | Professional & scientific | 2003 |
| K Walsh Electrical Services Limited | Construction | 2003 |
| K&K 49 Limited | Financial services | 2021 |
| K.B. Builders Limited | Construction | 2002 |
| K.P. Waste Company Limited | Water & waste | 1995 |
| K2 Trading Limited | Wholesale & retail | 2003 |
| KAI Distribution Centre Limited | Professional & scientific | 2001 |
| Kaked Ltd | Health & social care | 2013 |