| Janire Properties Ltd | Real estate | 2021 |
| Jason Farrow VFX Ltd | Information & communication | 2017 |
| Jasper Property Investment Limited | Real estate | 2018 |
| Jate Advisory Limited | Professional & scientific | 2026 |
| Javens Design Ltd | Construction | 2017 |
| JB Combustion Limited | Construction | 2016 |
| JB Innovation Consulting Limited | Administrative & support | 2019 |
| JB Investor Relations Ltd | Professional & scientific | 2019 |
| JC Global Trading Ltd | Wholesale & retail | 2018 |
| JCL Global Trading Ltd | Wholesale & retail | 2022 |
| JCR PR Limited | Professional & scientific | 2011 |
| JDB Locations Limited | Construction | 2016 |
| Jdcsi Solutions Limited | Professional & scientific | 2004 |
| JDS HR Services Limited | Professional & scientific | 2016 |
| Jdsk Holdings Ltd | Financial services | 2024 |
| Jdsk Property Ltd | Real estate | 2024 |
| JEM Childcare Recruitment Limited | Administrative & support | 2024 |
| Jemtob Limited | Professional & scientific | 2016 |
| JENB2 Limited | Real estate | 2024 |
| Jenkins Studio Ltd | Arts & recreation | 2015 |
| Jerome Solutions Ltd | Professional & scientific | 2012 |
| Jerry Chen Construction Ltd | Construction | 2018 |
| JFB Group Ltd | Real estate | 2025 |
| JFS Groundworks Ltd | Construction | 2021 |
| JFS Landscapes Ltd | Administrative & support | 2015 |
| JH Strategic Consulting Limited | Professional & scientific | 2016 |
| Jintro Limited | Professional & scientific | 2018 |
| JK Mortgage Brokers Ltd | Financial services | 2025 |
| Jlint Limited | Professional & scientific | 2014 |
| JLM (Design) Ltd | Professional & scientific | 2017 |
| JLN Flooring Ltd | Construction | 2022 |
| Jlrc Global Ltd | Wholesale & retail | 2022 |
| Jlsvr Ltd | Health & social care | 2014 |
| JM9AUTO Ltd | Wholesale & retail | 2022 |
| Jmast Consulting Ltd | Administrative & support | 2016 |
| Jmcsherry Consulting Ltd | Professional & scientific | 2025 |
| JMQ Recruitment Limited | Administrative & support | 2015 |
| Jnfinance (UK) Limited | Real estate | 2018 |
| JNJ Enterprise Limited | Health & social care | 2023 |
| JO FRY PR Limited | Professional & scientific | 2019 |
| JOD Projects Ltd | Construction | 2021 |
| John Drew Limited | Professional & scientific | 2014 |
| John Spriggs Ltd | Hospitality | 2020 |
| John Williams & Co Limited | Professional & scientific | 2019 |
| Jolie Enterprises Limited | Professional & scientific | 2021 |
| Jolliffe Property Investments Ltd | Real estate | 2023 |
| Joseph James Contractors Limited | Construction | 2024 |
| Joshua Lewis Carpentry & Construction Ltd | Manufacturing | 2021 |
| JP Equity Holdings Limited | Financial services | 2025 |
| Jppp Ventures Ltd | Wholesale & retail | 2023 |
| JPT Finance Limited | Administrative & support | 2014 |
| JPW Interims Limited | Professional & scientific | 2012 |
| JRL Bute Limited | Professional & scientific | 2021 |
| JRP Nominees Limited | Professional & scientific | 2015 |
| JT Biokinetics Limited | Health & social care | 2018 |
| JT Interestate Limited | Real estate | 1999 |
| Jtcunningham Consulting Ltd | Information & communication | 2019 |
| Jubilee Mansions Freehold (Peterborough) Limited | Real estate | 2014 |
| Jude Breeze Consulting Limited | Information & communication | 2021 |
| Juha Ltd | Professional & scientific | 2005 |
| Juha.Co.Uk Limited | Wholesale & retail | 2005 |
| Julia Castelli Lifestyle Management Ltd | Wholesale & retail | 2019 |
| Jumbo Maintenance Limited | Construction | 2001 |
| Juniper Court Management (Sutton) Limited | Households | 1973 |
| Just Annuities Limited | Professional & scientific | 2004 |
| Just ASK Miffy Limited | Administrative & support | 2023 |
| Just Cosec Ltd | Administrative & support | 2009 |
| Just Direct Limited | Professional & scientific | 2016 |
| Just Equity Release Limited | Professional & scientific | 2004 |
| Just Group PLC | Professional & scientific | 2013 |
| Just Protection Limited | Extraterritorial | 2007 |
| Just RE 1 Limited | Financial services | 2015 |
| Just RE 2 Limited | Financial services | 2015 |
| Just Retirement (Holdings) Limited | Financial services | 2004 |
| Just Retirement Finance PLC | Professional & scientific | 2014 |
| Just Retirement Group Holdings Limited | Financial services | 2009 |
| Just Retirement Limited | Financial services | 2004 |
| Just Retirement Management Services Limited | Administrative & support | 2003 |
| Just Retirement Money Limited | Financial services | 2015 |
| Just Retirement Nominees Limited | Professional & scientific | 2004 |
| Just Retirement Solutions Limited | Professional & scientific | 2016 |
| Jwhs Holdings Limited | Financial services | 2024 |
| K J Robins Ltd | Agriculture & fishing | 2022 |
| K M Parsonage Limited | Financial services | 2015 |
| K P J Inns Limited | Hospitality | 2004 |
| K R Savidge Plumbing & Heating Limited | Construction | 2011 |
| K2 Veterinary Referrals Limited | Professional & scientific | 2013 |
| KA Architectural Limited | Professional & scientific | 2017 |
| Kabod Enterprises Limited | Professional & scientific | 2023 |
| KAI DI (Erith) Ltd | Hospitality | 2017 |
| Kams Trading Post Limited | Wholesale & retail | 2025 |
| Kandi Reigate Ltd | Wholesale & retail | 2024 |
| Kane Paterson Consulting Limited | Information & communication | 2025 |
| Kane Paterson Limited | Information & communication | 2016 |
| Karb Retail Limited | Wholesale & retail | 2025 |
| Karima's Gardens Ltd | Administrative & support | 2021 |
| Karob Consulting Limited | Professional & scientific | 2017 |
| Kash Ventures Ltd | Real estate | 2004 |
| Kashfam Limited | Wholesale & retail | 2019 |
| Kate Lukas Eventing Ltd | Arts & recreation | 2007 |