| JJ Starlight Care Ltd | Public administration | 2018 |
| JJ Titan Limited | Professional & scientific | 2013 |
| JJI Paving Ltd | Construction | 2019 |
| JJL Design and Build Limited | Construction | 2004 |
| JJL Group Holdings Limited | Administrative & support | 2022 |
| JJM Assets Limited | Real estate | 2022 |
| JJN Craft Bar Ltd | Hospitality | 2019 |
| JJT Construction LLP | | 2023 |
| Jjttransport Ltd | Transport & logistics | 2026 |
| JK Panels Limited | Manufacturing | 2016 |
| Jkamazon Ltd | Wholesale & retail | 2023 |
| JKM Brickwork & Construction Ltd | Construction | 2010 |
| JKT Homes Limited | Real estate | 2025 |
| JL Renewable Solutions Ltd | Administrative & support | 2025 |
| JLI Enquirers Limited | Financial services | 2011 |
| JLK Workshop Products Ltd | Administrative & support | 2016 |
| JLO UK Trading Ltd | Wholesale & retail | 2024 |
| JLR Paint Solutions Ltd | Wholesale & retail | 2022 |
| Jltx Distribution Limited | Wholesale & retail | 2023 |
| Jlwbmedia Limited | Information & communication | 2023 |
| JM Fencing & Landscapes Ltd | Administrative & support | 2026 |
| JMA Catering Limited | Hospitality | 2019 |
| JME Enterprises Limited | Administrative & support | 2018 |
| JME Site Management Services Ltd | Construction | 2015 |
| JMJ Ltd | Construction | 2022 |
| JMN Convenience Limited | Extraterritorial | 2024 |
| Jmnl Benefits Limited | Financial services | 2017 |
| JN Ecommmerce Limited | Wholesale & retail | 2025 |
| JNA Hospitality Limited | Hospitality | 2025 |
| Joand Lettings Ltd | Real estate | 2024 |
| Joanne Dews Aesthetics Limited | Other services | 2018 |
| Joanne Mcmillan Care Ltd | Health & social care | 2025 |
| Joanne's Hair and Beauty Limited | Other services | 2017 |
| Jobmove Worldwide Limited | Administrative & support | 2016 |
| John Charles Limited | Administrative & support | 2020 |
| John Fowler Locomotives Limited | Extraterritorial | 2004 |
| John Harrhy & Sons Limited | Hospitality | 1990 |
| John Hodson & Sons Ltd | Manufacturing | 2017 |
| John the Butcher (Tamworth) Ltd | Wholesale & retail | 2020 |
| John Thomlinson Gardening Service Ltd. | Administrative & support | 2003 |
| Johnston Group Ltd | Financial services | 2025 |
| Joined UP Holdings Limited | Financial services | 2023 |
| Joined UP Words Limited | Professional & scientific | 2019 |
| Jojo Property Rentals Limited | Real estate | 2026 |
| Jokonyas Limited | Health & social care | 2016 |
| Jones & Egan Estates Holdings Limited | Professional & scientific | 2015 |
| Jones & Egan Estates Limited | Real estate | 2015 |
| Jones-Mcneill Restaurants Limited | Hospitality | 2018 |
| Jopla II Limited | Financial services | 2021 |
| Jopla III Limited | Financial services | 2023 |
| Jopla Limited | Financial services | 2018 |
| Jopla Racing Limited | Arts & recreation | 2023 |
| Josefsen Project Management Ltd | Extraterritorial | 2018 |
| Josephs Rentals & Retail Limited | Other services | 2021 |
| Josh Gain Consulting Limited | Professional & scientific | 2024 |
| Josh Stanton Racing & Events Limited | Arts & recreation | 2019 |
| Joyem Limited | Wholesale & retail | 2024 |
| JP Healthcare Recruitment Limited | Administrative & support | 2025 |
| JPB Property Holdings Ltd | Real estate | 2020 |
| JPH Signs Ltd | Professional & scientific | 2019 |
| JPR Group Services Ltd | Administrative & support | 2025 |
| JPR Logistics Ltd | Transport & logistics | 2020 |
| JPS Scaffold Limited | Construction | 2017 |
| JPW Contracts Ltd | Professional & scientific | 2025 |
| JR Motorcycles W&S Ltd | Wholesale & retail | 2025 |
| JR Williams Properties Ltd | Real estate | 2023 |
| JRB Rural Services Ltd | Agriculture & fishing | 2026 |
| JRD Partitions Limited | Construction | 2023 |
| JRP Transport Ltd | Transport & logistics | 2013 |
| JRW Design & Build Limited | Construction | 2007 |
| JSG Holdings Limited | Financial services | 2017 |
| JSH Healthcare Ltd | Health & social care | 2025 |
| JSK Plant Hire Limited | Administrative & support | 2019 |
| JSM 2026 Limited | Wholesale & retail | 2026 |
| JSP Logistics Ltd | Transport & logistics | 2017 |
| JSP Trading Group Limited | Wholesale & retail | 2025 |
| JT Paving Ltd | Construction | 2024 |
| JT Training & Assessment Ltd | Education | 2023 |
| JTF Wireless Limited | Wholesale & retail | 2012 |
| Jtwi Ltd | Wholesale & retail | 2021 |
| Judith & Co Recruitment Limited | Administrative & support | 2026 |
| Jungle Versatile Indoor Play Ltd | Arts & recreation | 2014 |
| Just ADD Guests Limited | Hospitality | 2021 |
| Just Chillin Limited | Administrative & support | 2023 |
| Just Geoff Limited | Professional & scientific | 2022 |
| Just Haulage Ltd | Transport & logistics | 2026 |
| Justguys Limited | Other services | 1995 |
| Juval Trans Limited | Transport & logistics | 2026 |
| Juxtaposition Architecture Birmingham Commercial Ltd | Professional & scientific | 2024 |
| Juxtaposition Architecture Birmingham Limited | Professional & scientific | 2023 |
| JV Construct and Design Limited | Construction | 2021 |
| JVJ Auto Services Ltd | Wholesale & retail | 2024 |
| JW Property Recruitment Limited | Administrative & support | 2025 |
| JWL Design Group Ltd | Manufacturing | 2026 |
| JWL Engineering Limited | Manufacturing | 2009 |
| Jworwood Limited | Manufacturing | 2024 |
| Jwpm Limited | Financial services | 2022 |
| K & D Construction Limited | Construction | 2010 |
| K & K Andrews Limited | Administrative & support | 2018 |
| K & L Lane Consultancy Ltd | Construction | 2024 |