| Jia's Garden Ltd | Hospitality | 2021 |
| Jifi Ltd | Transport & logistics | 2025 |
| Jigg FM UK Limited | Construction | 2018 |
| Jigsaw Interior Solutions Limited | Construction | 2019 |
| Jimmy Taylor Limited | Wholesale & retail | 2012 |
| Jishliyaana Ltd | Real estate | 2023 |
| JJ Business Limited | Information & communication | 2014 |
| JJ Fire Safety Systems Limited | Construction | 2006 |
| Jj.Darkoh Ltd. | Information & communication | 2016 |
| JJR Accounting & Taxation Ltd | Professional & scientific | 2018 |
| JJZ Electrical Ltd | Construction | 2019 |
| JK Electrical Installations Ltd | Construction | 2019 |
| JK Fast Couriers Ltd | Transport & logistics | 2021 |
| JK Pearl Ltd | Health & social care | 2021 |
| JK Project Consult Limited | Professional & scientific | 2025 |
| JK Psychology Services Limited | Health & social care | 2016 |
| JKH Plumbing and Heating UK Ltd | Construction | 2025 |
| JKN Construction Ltd | Construction | 2018 |
| JL Holding Enterprise Ltd | Professional & scientific | 2016 |
| JL Performance Sales Ltd | Wholesale & retail | 2023 |
| JL Strategic Communications Limited | Information & communication | 2016 |
| JLR Heating Services Ltd | Construction | 2023 |
| JLU Group Limited | Professional & scientific | 2024 |
| JM Engineering & Controls Ltd | Professional & scientific | 2017 |
| JM Monroe Limited | Wholesale & retail | 2022 |
| JM Properties Group Limited | Real estate | 2025 |
| JM PS Digital Ltd | Information & communication | 2026 |
| JM Steam Engineering Ltd | Professional & scientific | 2019 |
| JMA Solutions Ltd | Construction | 2026 |
| Jmaty Cleaning Services Ltd | Administrative & support | 2024 |
| JMF Electrical Limited | Construction | 2022 |
| JMG Home Improvements Ltd | Construction | 2026 |
| Jmichell Limited | Administrative & support | 2013 |
| JML Management Services Limited | Professional & scientific | 2024 |
| JMP Curzon Electrical Services Limited | Construction | 2009 |
| JMP Logistics Ltd | Transport & logistics | 2019 |
| JMP Sealants Limited | Construction | 2023 |
| Jmrh Holdings Limited | Financial services | 2016 |
| JMS Automotive Ltd | Financial services | 2014 |
| JNC Transportation Ltd | Transport & logistics | 2016 |
| JNG Sourcing Ltd | Administrative & support | 2024 |
| JNJ Properties Ltd | Real estate | 2023 |
| JNK Limited | Information & communication | 2015 |
| JNP Group Consulting Engineers Limited | Professional & scientific | 2016 |
| JNP Group Holding Limited | Financial services | 2021 |
| JNP Plastering & Construction Ltd | Construction | 2015 |
| Jo-Ondot-Delivereez Ltd | Transport & logistics | 2018 |
| Jo-Ondot-Jobz Limited | Administrative & support | 2023 |
| JOE Vaughan Consultancy Limited | Professional & scientific | 2018 |
| John Biggam Ltd | Professional & scientific | 2014 |
| John Burrows Surveying Services Ltd | Other services | 2017 |
| John C Benjamin Limited | Administrative & support | 1998 |
| John Dennis 4X4 Limited | Wholesale & retail | 2011 |
| John Lawford Building Services Limited | Construction | 2002 |
| John Mitch Ltd | Real estate | 2021 |
| John Mooney Investigative Services Limited | Administrative & support | 2012 |
| John Vial Limited | Other services | 2015 |
| John Vial Services Ltd | Professional & scientific | 2015 |
| John W Bramall Limited | Health & social care | 2005 |
| John's Parcel Services Ltd | Transport & logistics | 2026 |
| Johnjameslandandproperty Ltd | Administrative & support | 2011 |
| Johnny Grey Limited | Construction | 1999 |
| Johnston Baker LP | | 2006 |
| Joiner & SON Builders Ltd | Construction | 2023 |
| Joint Medical Solutions Limited | Health & social care | 2013 |
| Jojema African Store Ltd | Hospitality | 2010 |
| Jonanet Property Ltd | Real estate | 2026 |
| Jones Ferguson Properties Ltd | Real estate | 2025 |
| Jonquil Services Limited | Information & communication | 2006 |
| Jordans Jewellers Limited | Other services | 1995 |
| Jordans Mews Freehold Company Limited | Households | 2015 |
| Joseph Benjamin Marquees Limited | Administrative & support | 2010 |
| Joseph Jameson Evans Limited | Professional & scientific | 2006 |
| Jott Limited | Professional & scientific | 2005 |
| Joubert Trading Limited | Professional & scientific | 2015 |
| Journeyswith Ltd | Administrative & support | 2022 |
| Joy Care Solutions Ltd | Health & social care | 2025 |
| Joy Limited | Wholesale & retail | 2005 |
| Joy Partners CIC | Health & social care | 2026 |
| Joyce Media Production Ltd | Information & communication | 2026 |
| Joyce Property Investments Ltd | Real estate | 2025 |
| Joycemediagroup Ltd | Information & communication | 2024 |
| Joyglen Ltd | Administrative & support | 2019 |
| JP Design & Build Ltd | Construction | 2026 |
| JPB Electrical Contractors Ltd | Construction | 2021 |
| Jpbh Consulting Limited | Information & communication | 1998 |
| JPJ Properties Enterprise Ltd | Real estate | 2023 |
| JPP Commerce Ltd | Wholesale & retail | 2025 |
| JPR96PROPERTY Ltd | Real estate | 2026 |
| JPS Homes Limited | Real estate | 2003 |
| JPW Bespoke Carpentry Limited | Manufacturing | 2026 |
| JR Plumbing & Heating Solutions Ltd | Construction | 2016 |
| JR Property Legacy Ltd | Construction | 2025 |
| JR Winters Ltd | Construction | 2021 |
| JRT Preservations Ltd | Construction | 2024 |
| JS and Sons Properties Ltd | Real estate | 2022 |
| JS Digital Solutions Ltd | Professional & scientific | 2025 |
| JSH Carpentry & Building Ltd | Construction | 2017 |
| JSK Technologies Limited | Information & communication | 2012 |
| JSL Carpentry Ltd | Manufacturing | 2019 |