| Jianway Ltd | Information & communication | 2004 |
| Jiao Ltd | Information & communication | 2024 |
| Jigger Muddle Shake PUB Group Limited | Hospitality | 2019 |
| Jigsaw Access Financial Advice Ltd | Financial services | 2003 |
| Jigsaw Arts Berkhamsted LLP | | 2025 |
| Jigsaw Capital Limited | Administrative & support | 2017 |
| Jigsaw P1 LLP | | 2019 |
| JIM Denning Ltd | Professional & scientific | 2026 |
| Jimeba Ltd | Wholesale & retail | 2026 |
| Jint Property Limited | Real estate | 2022 |
| JIO Services Limited | Information & communication | 2009 |
| Jirtec Ltd | Information & communication | 2023 |
| JJ Matharu Holiday LET Ltd | Hospitality | 2024 |
| JJB Communications Limited | Professional & scientific | 2018 |
| Jjchoong Consulting Ltd | Professional & scientific | 2014 |
| Jjrm Flooring Ltd | Construction | 2023 |
| JJS Todd Ltd | Health & social care | 2025 |
| Jjvv Ltd | Professional & scientific | 2025 |
| JK Goalkeeping Limited | Arts & recreation | 2025 |
| JK Response Services Ltd | Other services | 2021 |
| JKL Tribe Limited | Information & communication | 2018 |
| JKR Motorglass Limited | Wholesale & retail | 2020 |
| JL Contractors Ltd | Construction | 2019 |
| JL Dennis Ltd | Professional & scientific | 2019 |
| JL Global Investments Ltd | Real estate | 2025 |
| Jlgb Tech Limited | Wholesale & retail | 2022 |
| JLL Coaching Ltd | Education | 2024 |
| Jltg Designs Ltd | Manufacturing | 2026 |
| JM Events Group Ltd | Arts & recreation | 2026 |
| JM HR Consulting Limited | Extraterritorial | 2015 |
| JM Plumbing Services Limited | Construction | 2015 |
| JME ST Albans Limited | Hospitality | 2023 |
| Jmhwc Limited | Professional & scientific | 2024 |
| JNP Medical Technologies Limited | Manufacturing | 2022 |
| JO Couchman Limited | Professional & scientific | 2016 |
| JO Underhill Ltd | Information & communication | 2025 |
| Joana Technologies Limited | Information & communication | 2024 |
| Joanna DAI Limited | Administrative & support | 2016 |
| Joanna Lauder Ltd | Administrative & support | 2013 |
| Joanna Taylor Ltd | Professional & scientific | 2024 |
| Jobu London Limited | Other services | 2019 |
| Joda-Hauz Limited | Real estate | 2019 |
| Jogeye Limited | Information & communication | 2025 |
| Johansson Toxin Free Living Ltd | Wholesale & retail | 2025 |
| John Jameson Limited. | Real estate | 1962 |
| John Pudney Holdings Limited | Financial services | 2009 |
| John Sisk & SON Limited | Construction | 1985 |
| John Somerville Sculptures Limited | Wholesale & retail | 2025 |
| John Standing Limited | Transport & logistics | 2009 |
| John the Butcher Limited | Wholesale & retail | 2015 |
| John Vercoe Limited | Professional & scientific | 2014 |
| Johnston Organisational Consulting Ltd | Professional & scientific | 2021 |
| Joint Property Investments (UK) Limited | Households | 2020 |
| Jointers ANG Ltd | Construction | 2015 |
| Jolie Store Ltd | Wholesale & retail | 2023 |
| Jolivr Investing Limited | Financial services | 2024 |
| Jolly Sailor ST Albans Ltd | Hospitality | 2025 |
| Jonathan FOY Limited | Professional & scientific | 2019 |
| Jorn Technologies Limited | Information & communication | 2011 |
| Joseph Edwards Baritone Ltd | Arts & recreation | 2021 |
| Josh Lamonaca Consultancy Limited | Professional & scientific | 2025 |
| Josh Plaut Ltd | Health & social care | 2015 |
| Joshua Lamonaca Ltd | Financial services | 2019 |
| Jotat Ltd | Construction | 2021 |
| Joyce Group Limited | Construction | 2016 |
| Joyful Stevens Ltd | Information & communication | 2026 |
| JP Consultants Ltd | Information & communication | 2025 |
| JP Management Exclusive Ltd | Information & communication | 2024 |
| JP Mitchell Consulting Limited | Professional & scientific | 2010 |
| JP Yates Limited | Other services | 2023 |
| JPA Furniture Limited | Extraterritorial | 2018 |
| JPA Workspaces Limited | Extraterritorial | 2021 |
| Jpinvcats Tslc I LLP | | 2021 |
| JPR Studio Ltd | Professional & scientific | 2023 |
| JR Welch Solutions Ltd | Information & communication | 2025 |
| JS Data Solutions Limited | Professional & scientific | 2008 |
| JS Golf Services Ltd | Wholesale & retail | 2012 |
| JS Props Services Ltd | Information & communication | 2014 |
| JS Restylez Limited | Construction | 2020 |
| JS2 Health Limited | Public administration | 2023 |
| Jsbeekay (UK) Ltd | Extraterritorial | 2015 |
| JSM Ventures Ltd | Information & communication | 2023 |
| JSS Property Holdings Ltd | Real estate | 2021 |
| JST Developments Limited | Real estate | 2020 |
| JT Event Truck Limited | Transport & logistics | 2016 |
| JTC Training Ltd | Other services | 2015 |
| JTD Associates Ltd | Professional & scientific | 2014 |
| JTS Roofing & Guttering Ltd | Construction | 2025 |
| Juan & Juan Ltd | Wholesale & retail | 2021 |
| JUB Capital Ltd | Financial services | 2013 |
| Judd Consulting (UK) Ltd | Professional & scientific | 2009 |
| Judge 3D Limited | Administrative & support | 2005 |
| Judica Ltd | Public administration | 2024 |
| Juggernaut Software Solutions Ltd | Information & communication | 2022 |
| Juju Beauty Care Ltd | Wholesale & retail | 2014 |
| Jules Construction Services Limited | Construction | 2019 |
| Julia Boston Antiques Ltd | Wholesale & retail | 2018 |
| Jumla RVP I LP | | 2021 |
| Jumla RVP II LP | | 2022 |
| Jungle Services Limited | Construction | 2025 |