| JAG Homes Limited | Construction | 2005 |
| Jaggarage Ltd | Wholesale & retail | 2020 |
| Jaiden Mitchell TM Ltd | Public administration | 2025 |
| Jaisa Ltd | Health & social care | 2022 |
| Jaja Bings Ltd | Hospitality | 2022 |
| JAK Engineering Design Services Ltd | Professional & scientific | 2025 |
| JAK Property and Maintenance Ltd | Construction | 2024 |
| Jakab Trans Ltd | Transport & logistics | 2018 |
| Jakash Marketing and Design Ltd | Professional & scientific | 2023 |
| Jake Allert Holdings Ltd | Financial services | 2024 |
| Jake Jaggers TM Ltd | Public administration | 2024 |
| Jake's Adventures Petcare Ltd | Agriculture & fishing | 2019 |
| Jakeecom Limited | Wholesale & retail | 2024 |
| Jakon Consultancy & Development Ltd | Hospitality | 2025 |
| Jakto Excavations Ltd | Construction | 2025 |
| JAL Legal Ltd | Professional & scientific | 2015 |
| JAM FAM One Ltd | Construction | 2024 |
| JAM JAR Property Investments Limited | Real estate | 2021 |
| JAM Master Ltd | Wholesale & retail | 2026 |
| JAM Property Solutions Ltd | Real estate | 2016 |
| JAM Refinishing Supplies Limited | Wholesale & retail | 2026 |
| Jamar Truck Ltd | Transport & logistics | 2015 |
| Jambojimbo Limited | Professional & scientific | 2025 |
| James Andrew Interiors Ltd | Wholesale & retail | 2014 |
| James Bond Events Limited | Administrative & support | 2026 |
| James Dorrin TM Ltd | Public administration | 2025 |
| James Flint Boxing Ltd | Arts & recreation | 2025 |
| James Hall Property Services Limited | Real estate | 2017 |
| James Lowe Graphic Design Limited | Professional & scientific | 2019 |
| James Martin & Associates Ltd. | Professional & scientific | 2014 |
| James Morton TM Ltd | Other services | 2022 |
| James Motor Company (Yorks) Limited | Wholesale & retail | 2019 |
| James Parker TM Ltd | Public administration | 2025 |
| James Property (Doncaster) Limited | Real estate | 2024 |
| James Raban Ltd | Wholesale & retail | 2022 |
| James Rajah Limited | Administrative & support | 2018 |
| James Rilett Construction Ltd | Construction | 2018 |
| James Ruane & Sons (Seeds) Limited | Professional & scientific | 1962 |
| James Ruane & Sons (Yorks) Holdings Limited | Wholesale & retail | 1938 |
| James Smith Construction Ltd | Construction | 2015 |
| James Solutions Ltd | Real estate | 2024 |
| James Taylor 92 Ltd | Construction | 2023 |
| James Usher & SON Limited | Wholesale & retail | 1941 |
| James Watson (Scaffolding) Limited | Construction | 2007 |
| JAMES123 Limited | Wholesale & retail | 2026 |
| JAMES123LIMITED Ltd | Professional & scientific | 2026 |
| JAMESLUKE1 Ltd | Public administration | 2019 |
| James` Barber Shop Limited | Other services | 2003 |
| Jamfadkemadex Limited | Hospitality | 2026 |
| Jamie & Khloe Ltd | Public administration | 2022 |
| Jamie Godfrey Ltd | Wholesale & retail | 2013 |
| Jamie Mcdonnell Enterprises Ltd | Administrative & support | 2011 |
| Jamie Smith TM Ltd | Public administration | 2024 |
| Jamil Farooq TM Ltd | Public administration | 2024 |
| Jamison Food and Wine Ltd | Wholesale & retail | 2022 |
| JAN Kucyk Ltd | Transport & logistics | 2014 |
| Jan&M Groundwork Limited | Construction | 2018 |
| Jandelmarket Ltd | Information & communication | 2025 |
| Jane Needham Ltd | Professional & scientific | 2012 |
| Jane Price-Stephens Interior Design Ltd | Administrative & support | 2009 |
| Jania Hairs World Ltd | Other services | 2026 |
| Janitor Services Ltd | Administrative & support | 2025 |
| JAP Enterprise's Ltd | Administrative & support | 2023 |
| Japin Ltd | Information & communication | 2022 |
| Jardin DE Flores Ltd | Professional & scientific | 2018 |
| Jaricol Properties Limited | Real estate | 2002 |
| JARO82 Ltd | Transport & logistics | 2015 |
| Jartrans Ltd | Transport & logistics | 2013 |
| Jarwik Ltd | Wholesale & retail | 2019 |
| JAS Civils Ltd | Construction | 2025 |
| JAS Digitech Limited | Information & communication | 2016 |
| JAS Dream Homes Ltd | Real estate | 2021 |
| JAS Engineering Ltd | Professional & scientific | 2018 |
| Jask Media Ltd | Professional & scientific | 2019 |
| Jasmine Croft Limited | Households | 2025 |
| Jasmine Developments Ltd | Construction | 2020 |
| Jasmine Doncaster Limited | Administrative & support | 2015 |
| Jasmine Moon Properties Limited | Real estate | 2026 |
| Jason Clark Limited | Other services | 2004 |
| Jason Healthcare Ltd | Health & social care | 2023 |
| Jason Major Delivery Ltd | Transport & logistics | 2026 |
| Jason Parkin Tiling Limited | Construction | 2011 |
| Jason Sohal Limited | Transport & logistics | 2023 |
| Jason Whiteley Limited | Professional & scientific | 2023 |
| Jatk Investments Ltd | Real estate | 2026 |
| Jatt AI Transport Ltd | Transport & logistics | 2026 |
| Jatts Services Ltd | Construction | 2024 |
| Jatts Solutions Support Ltd | Construction | 2025 |
| Java Developments Limited | Construction | 2020 |
| Javea Consultancy Ltd | Professional & scientific | 2024 |
| JAW Dental Limited | Health & social care | 2025 |
| Jayne Daines Limited | Other services | 2007 |
| Jaysters Catering Bawtry Limited | Hospitality | 2011 |
| Jaytec Limited | Professional & scientific | 2025 |
| Jazanne Arts Community Interest Company | Arts & recreation | 2017 |
| Jazz Shop Limited | Wholesale & retail | 2024 |
| JB & DM Property Investments Limited | Real estate | 2023 |
| JB Coatings Ltd | Construction | 2023 |
| JB Contracting Services Limited | Construction | 2025 |
| JB Gestalt Psychotherapy Ltd | Health & social care | 2026 |