| JMB Electrical (UK) Limited | Construction | 2017 |
| JMC Consultancy Group Ltd | Professional & scientific | 2026 |
| JMD Group Private Ltd | Wholesale & retail | 2025 |
| JME Nautica Ltd | Manufacturing | 2025 |
| JMF Biotech Consulting Limited | Professional & scientific | 2021 |
| JMG Composites Ltd | Manufacturing | 2023 |
| Jmgr Property Investments Ltd | Real estate | 2025 |
| Jmmi Co., Ltd | Other services | 2021 |
| JMP Developments Limited | Professional & scientific | 1999 |
| Jmpm Investments Limited | Extraterritorial | 2010 |
| Jmstevens Ltd | Construction | 2021 |
| JMT Cambridge Ltd Ltd | Hospitality | 2025 |
| JNJ Virgo Services Limited | Real estate | 2014 |
| JNO Hope Limited | Health & social care | 2013 |
| JNR Systems Limited | Information & communication | 2015 |
| JNS Group Ltd | Financial services | 2024 |
| JNS Innovation Ltd | Professional & scientific | 2009 |
| JO Alexander Limited | Wholesale & retail | 2005 |
| JO Hedley Consulting Ltd | Professional & scientific | 2023 |
| JO Mills Consulting Limited | Professional & scientific | 2016 |
| Joan LAB Equipment Co., Ltd | Extraterritorial | 2016 |
| Joanna Kudryńska Unltd | Professional & scientific | 2019 |
| Joao Alarcon Ltd | Manufacturing | 2023 |
| Joao Andrade Ltd | Manufacturing | 2025 |
| Jobay Music Ltd | Information & communication | 2018 |
| Jobjar Ltd | Administrative & support | 2020 |
| Jobrite Landscaping Ltd | Administrative & support | 2007 |
| Jodael Advanced Materials Ltd | Manufacturing | 2026 |
| Joden International Ltd | Extraterritorial | 2014 |
| JOE Jackson Homes Limited | Construction | 2024 |
| Joe's Auto Locksmith Ltd | Wholesale & retail | 2025 |
| Joe's Auto Tuning Ltd | Wholesale & retail | 2026 |
| Joel Gustafsson Consulting Limited | Professional & scientific | 2020 |
| Joelin Limited | Administrative & support | 2012 |
| John Balliol Court (Residents) Limited | Households | 1998 |
| John Fast Ltd | Manufacturing | 2024 |
| John Foster Fine Art Ltd | Wholesale & retail | 2012 |
| John Gaunt Pump Supplies Limited | Wholesale & retail | 1999 |
| John Huntingdon's Charity | Other services | 2007 |
| John Kirk Building & Construction Ltd | Construction | 2024 |
| John Mcgregor Ltd | Arts & recreation | 2002 |
| John Mcnamara Consulting Limited | Professional & scientific | 2010 |
| John Mortimer Property Management Limited | Professional & scientific | 1990 |
| John Neill Carpenter Ltd | Construction | 2025 |
| John Roman Properties Limited | Real estate | 2014 |
| Johnson Architects Limited | Professional & scientific | 2012 |
| Johnson Avenue Management Company Limited | Households | 2004 |
| Johnson Brothers (Redditch) Limited | Transport & logistics | 1955 |
| Johnson Heating and Plumbing Limited | Construction | 2003 |
| Johnsonsharpe Limited | Professional & scientific | 2022 |
| Join Homecare Ltd | Health & social care | 2022 |
| Joint Analytics Limited | Manufacturing | 2017 |
| Joint Colleges Nursery (Cambridge) Limited(The) | Education | 1980 |
| Joint Inspection Group Limited | Information & communication | 2002 |
| JOMAR2001-AVIA Ltd | Manufacturing | 2024 |
| JON & Bash Ltd | Other services | 2024 |
| JON Hearn Lighting Technician Limited | Professional & scientific | 2025 |
| JON Removals Ltd | Transport & logistics | 2025 |
| JON Tilston Ltd | Professional & scientific | 2020 |
| JON Wells Design Limited | Professional & scientific | 2004 |
| Jona Holdings Ltd. | Other services | 2023 |
| Jonatas Rossi Consulting Ltd | Information & communication | 2019 |
| Jonathan Kerby Limited | Administrative & support | 2004 |
| Jonathan Law Limited | Information & communication | 2019 |
| Jonathan Wheeler Consultancy Limited | Professional & scientific | 2021 |
| Jones Publishing Limited | Professional & scientific | 2008 |
| Jones Silva Ltd | Manufacturing | 2026 |
| Jonson's Connections Limited | Professional & scientific | 2014 |
| Jonyu Property Limited | Real estate | 2019 |
| Joogee Group Limited | Information & communication | 2021 |
| Jorbagreenlandsolutions Ltd | Construction | 2026 |
| Jord Surveys Ltd | Professional & scientific | 2023 |
| Jorgar Ltd | Construction | 2005 |
| Joroi Limited | Financial services | 2022 |
| Joseph Heap & Sons Limited | Professional & scientific | 1982 |
| Joseph Heap Property Limited | Real estate | 2003 |
| Joseph Lewis & Co Limited | Real estate | 2025 |
| Joseph Mcmanniman Ltd | Construction | 2006 |
| Josh Curtis Music Ltd | Arts & recreation | 2025 |
| Josh K FAY Ltd | Information & communication | 2018 |
| Joshiverse Ltd | Professional & scientific | 2026 |
| Joshua Aviation Ltd | Manufacturing | 2025 |
| Joshua Hosrey Ltd | Wholesale & retail | 2026 |
| Jost Music Limited | Arts & recreation | 2019 |
| JOT Flying Services Ltd | Education | 2021 |
| Joud Ltd | Hospitality | 2026 |
| Journai Ltd | Information & communication | 2024 |
| Journal for Social Innovation Limited | Information & communication | 2025 |
| Journey HR Limited | Administrative & support | 2010 |
| Jowish Co., Ltd | Wholesale & retail | 2025 |
| Joy FAN Jewelry Co., Limited | Wholesale & retail | 2024 |
| Joyful Dolphin Swim Ltd | Health & social care | 2014 |
| Joyful YI XIN Limited | Administrative & support | 2025 |
| Joyglobal International Holdings Ltd | Professional & scientific | 2015 |
| Joymatrix Limited | Information & communication | 2024 |
| Joyray International Corp. Limited | Professional & scientific | 2010 |
| Joystays Property Ltd | Real estate | 2026 |
| Joystone Property Ltd | Real estate | 2025 |
| Jozaca Co | Professional & scientific | 2016 |
| JP Arbitrage Ltd | Wholesale & retail | 2026 |