| Jenadi Limited | Health & social care | 2018 |
| Jennings & Stollery Limited | Construction | 2003 |
| Jensen Beauty Aesthetics Ltd | Other services | 2025 |
| Jerdonn Services Ltd | Health & social care | 2025 |
| Jerivia Support Services Ltd | Health & social care | 2025 |
| Jerros International Limited | Information & communication | 2019 |
| Jesse Wren Limited | Transport & logistics | 2016 |
| Jessica Betts Limited | Other services | 2014 |
| Jessica Ferrari-Wells Nutrition Limited | Health & social care | 2023 |
| Jessica Mescall Casting Ltd | Arts & recreation | 2025 |
| Jesslar Holdings Limited | Financial services | 2016 |
| Jessop Plumbing and Heating Limited | Construction | 2014 |
| Jesterino Ltd | Wholesale & retail | 2025 |
| JET SET Bites Ltd | Hospitality | 2023 |
| Jethen House Ltd | Education | 2022 |
| Jewels and Antiques UK Limited | Wholesale & retail | 2013 |
| JEX Shoes Limited | Wholesale & retail | 2017 |
| JF Naija Kitchen Limited | Hospitality | 2026 |
| JF Sports Limited | Information & communication | 2012 |
| Jfbco Ltd | Professional & scientific | 2025 |
| JFF Consultancy Limited | Information & communication | 2025 |
| JGS Notary Limited | Professional & scientific | 2023 |
| JH Acquisitions Ltd | Professional & scientific | 2023 |
| JH Sales Ltd | Wholesale & retail | 2025 |
| Jhas Accountancy Ltd | Extraterritorial | 2009 |
| Jheelan Associates Limited | Professional & scientific | 2004 |
| Jhei Properties Limited | Real estate | 2020 |
| JHL Timber Ltd | Wholesale & retail | 2021 |
| Jhmorgancolchester Ltd | Professional & scientific | 2025 |
| JHS Investment Limited | Real estate | 2018 |
| Jiggins Environmental Ltd | Water & waste | 2015 |
| Jigsaw Investments Ltd | Construction | 2021 |
| Jildos Limited | Transport & logistics | 2021 |
| JIM Carter Photography Ltd | Information & communication | 2021 |
| JIM Davies Productions Limited | Information & communication | 2014 |
| Jimbos Pukka Pints Ltd | Hospitality | 2020 |
| Jimmy Jewell Limited | Extraterritorial | 2009 |
| Jimson Tyres Limited | Wholesale & retail | 2015 |
| Jinxy Jane Limited | Wholesale & retail | 2017 |
| JIO Ventures Limited | Construction | 2016 |
| JIR5 Global Limited | Information & communication | 2016 |
| Jireh Holdings Ltd | Financial services | 2023 |
| Jireh Meals Limited | Hospitality | 2025 |
| Jitters Limited | Wholesale & retail | 2003 |
| JJ & Sons Entertainments Limited | Hospitality | 2017 |
| JJ Courier Contractors Limited | Transport & logistics | 2021 |
| JJ Lennox Properties Ltd | Real estate | 2024 |
| JJ Woods Electrical Ltd | Construction | 2024 |
| JJD Investments Limited | Construction | 2013 |
| JJD Roofing & Building Contractors Ltd | Construction | 2026 |
| JJG Properties Management Limited | Real estate | 2022 |
| JJM (East Anglia) Limited | Real estate | 2016 |
| Jjnl Leisure Ltd | Arts & recreation | 2025 |
| Jjnl Limited | Other services | 2025 |
| JJR Nevada Ltd | Extraterritorial | 2022 |
| JK Digital Ltd | Wholesale & retail | 2026 |
| JK Electrical & Building Services Ltd | Construction | 2015 |
| JK Gems Ltd | Wholesale & retail | 2017 |
| JK News Ltd | Wholesale & retail | 2018 |
| Jk&S Consult Limited | Construction | 2019 |
| JKG Premier Ltd | Wholesale & retail | 2021 |
| JKI Holdings Limited | Financial services | 2021 |
| JKI Investments Limited | Real estate | 2015 |
| JKJ Surveys Limited | Professional & scientific | 2016 |
| Jkmkroofcoating Limited | Construction | 2025 |
| JKR Party Productions Ltd | Arts & recreation | 2025 |
| JKV Accounting Services Ltd | Professional & scientific | 2015 |
| JL & JA Ltd | Wholesale & retail | 2025 |
| JL at Golden Hair & Beauty Limited | Other services | 2023 |
| JL Physio Limited | Other services | 2021 |
| JLA Products Ltd | Wholesale & retail | 2022 |
| JLB Group Ltd | Construction | 2024 |
| JLD Scaffolding Limited | Construction | 2025 |
| JLF Scaffolding Ltd | Construction | 2025 |
| JLM Property Management Ltd | Real estate | 2021 |
| JM Construction and Building Limited | Construction | 2022 |
| JM Dwellings (Essex) Ltd | Real estate | 2024 |
| JM Kurkiewicz Managment Limited | Manufacturing | 2023 |
| JM Training Ltd | Other services | 2020 |
| JMB Devco Limited | Construction | 2026 |
| JMG Quality Management Ltd | Administrative & support | 2009 |
| JMJ Architectural Design Ltd | Professional & scientific | 2023 |
| JMJ Compliance Ltd | Professional & scientific | 2025 |
| JMK Assessors Ltd | Financial services | 2018 |
| JML Construction Ltd | Construction | 2025 |
| JMM Construction Limited | Information & communication | 2014 |
| JMM Transport Ltd | Transport & logistics | 2016 |
| JMS Carpentry and Building Services Ltd | Construction | 2023 |
| JMS Facilities Ltd | Administrative & support | 2006 |
| JMT AS Ltd | Professional & scientific | 2017 |
| JN Consulting & Finance Ltd | Professional & scientific | 2023 |
| JN Management Barn Limited | Real estate | 2025 |
| JN Massage & Recovery Centre Limited | Other services | 2024 |
| JNL Plastering Ltd | Construction | 2026 |
| JNL Solutions Ltd | Wholesale & retail | 2018 |
| JO Mitchell Limited | Administrative & support | 2017 |
| Joaliya Publishing Ltd | Information & communication | 2023 |
| Joanna Clark Limited | Real estate | 2010 |
| Joanna Green Art Ltd | Arts & recreation | 2026 |
| Joanne Kelly Legal Limited | Financial services | 2024 |