| J. Smith Metals Limited | Water & waste | 1984 |
| J. Watson & Sons Limited | Water & waste | 2008 |
| J. Wilkinson Electrical Limited | Construction | 2004 |
| J.A Enterprise 24/7 Ltd | Transport & logistics | 2018 |
| J.A.B. Property (Midlands) Ltd | Real estate | 2017 |
| J.A.C.T Automotive Security Solutions Ltd | Wholesale & retail | 2025 |
| J.B. (Europe) Limited | Real estate | 1997 |
| J.C.A. Construction Limited | Construction | 2005 |
| J.D. Marketing & Industrial Services Limited | Professional & scientific | 1974 |
| J.E.M Professional Limited | Professional & scientific | 2011 |
| J.L.F Trading Limited | Other services | 2026 |
| J.N. Dairies Limited | Wholesale & retail | 1996 |
| J.N.Dairies Processing Limited | Extraterritorial | 2011 |
| J.O.Obomwan Transport Limited | Transport & logistics | 2017 |
| J.R. Wooddisse and Company Limited | Health & social care | 1960 |
| J.S Dhaliwal Electrical Services Ltd | Construction | 2025 |
| J.S Logistical Services Ltd | Transport & logistics | 2022 |
| J.S.D Delivery Service Ltd | Transport & logistics | 2024 |
| J.S.M. Properties Limited | Real estate | 1984 |
| J.S.Park Homes Ltd | Construction | 2021 |
| J.T Gray Theatre Scrub Ltd | Health & social care | 2023 |
| J.W. Green Swimming Pools Limited | Construction | 1980 |
| J.W.R. Consultancy Limited | Information & communication | 2001 |
| J1 Concrete Pumps Limited | Construction | 2016 |
| J1HOME Designs Limited | Construction | 2025 |
| J4M Security Services UK Ltd | Wholesale & retail | 2022 |
| J84 Limited | Real estate | 2021 |
| JA Griffin Consultancy Ltd | Information & communication | 2023 |
| Jaabx Ltd | Wholesale & retail | 2026 |
| Jaap Transport Ltd | Transport & logistics | 2022 |
| Jaarc Ltd | Wholesale & retail | 2004 |
| JAB Groundworks Limited | Construction | 2021 |
| Jabill Travels and Tours Limited | Hospitality | 2022 |
| JAC Healthcare Limited | Health & social care | 2006 |
| JAC Precision Engineering Limited | Manufacturing | 2005 |
| Jack Brookes & Co Limited | Real estate | 1937 |
| Jack Moody Logistics Limited | Transport & logistics | 2015 |
| Jack UK Limited | Manufacturing | 2005 |
| Jackson Forklift Limited | Wholesale & retail | 1984 |
| Jackson's of Shifnal Limited | Wholesale & retail | 2014 |
| Jackys Global Ltd | Professional & scientific | 2026 |
| Jacob Brown Consultancy Limited | Health & social care | 2016 |
| Jacob L Properties Ltd | Real estate | 2025 |
| Jacob Logistics Groups Ltd | Transport & logistics | 2025 |
| Jacob's Table Ltd | Hospitality | 2025 |
| Jacobs Electrical Ltd | Construction | 2026 |
| Jacobs Healthcare Ltd | Health & social care | 2019 |
| Jacorn Specialist Carpentry and Joinery Ltd | Construction | 2008 |
| Jacques Abbe Group Ltd | Wholesale & retail | 2019 |
| Jadaro Ltd | Wholesale & retail | 2014 |
| Jade Garden (Midlands) Ltd | Hospitality | 2017 |
| Jade House Wolverhampton Limited | Hospitality | 2024 |
| Jady's Events & Rentals Ltd | Administrative & support | 2025 |
| Jafsal Limited | Wholesale & retail | 2014 |
| Jafsat Solutions Ltd | Information & communication | 2019 |
| Jagaur Limited | Administrative & support | 2019 |
| Jagga Limited | Information & communication | 2018 |
| Jaggu Transport Ltd | Transport & logistics | 2018 |
| Jagjot Transport Ltd | Administrative & support | 2017 |
| Jagoptics Ltd | Health & social care | 2022 |
| Jagpal Studio Limited | Information & communication | 2025 |
| Jags Grab Ltd | Transport & logistics | 2026 |
| Jagsa Ltd | Real estate | 2025 |
| Jaguar Tools Limited | Wholesale & retail | 2009 |
| Jaguar Transport Limited | Transport & logistics | 2020 |
| Jaguar Tyre Services Ltd | Wholesale & retail | 2017 |
| Jahasoft Ltd | Information & communication | 2023 |
| Jahima Limited | Real estate | 2022 |
| JAI Bains Properties Limited | Real estate | 2018 |
| JAI Sharda Disposables N Hardware Ltd | Wholesale & retail | 2024 |
| Jaidan Homes Limited | Real estate | 2016 |
| Jaikaar Ltd | Financial services | 2024 |
| Jainaba's Boutique Ltd | Wholesale & retail | 2020 |
| Jaivant Patel Company CIC | Arts & recreation | 2020 |
| Jaiya Pharma Supplies Ltd | Wholesale & retail | 2023 |
| Jakhu Apna Food Wholesale Ltd | Wholesale & retail | 2023 |
| Jakhu Builder Ltd | Construction | 2019 |
| Jakhu Estates Ltd | Real estate | 2023 |
| Jakhu Ltd | Real estate | 2016 |
| Jalcon Ltd | Transport & logistics | 2024 |
| JAM & Company Limited | Wholesale & retail | 2011 |
| JAM Property Maintenance Limited | Real estate | 2024 |
| JAM Staffing Solutions (London) Ltd | Extraterritorial | 2021 |
| JAM Staffing Solutions (Midlands) Ltd | Extraterritorial | 2021 |
| JAM Staffing Solutions Ltd | Administrative & support | 2021 |
| Jamcom Supply Limited | Other services | 2019 |
| James & Huntley (Homecraft) Limited | Manufacturing | 1994 |
| James and Huntley Limited | Real estate | 1971 |
| James Cole Agencies Limited | Professional & scientific | 2012 |
| James David Homes Limited | Real estate | 2022 |
| James Gregory Financial Limited | Financial services | 2013 |
| James Gregory Properties Limited | Real estate | 2016 |
| James Rose Homes Limited | Real estate | 2021 |
| James Willis Coaching Ltd | Education | 2023 |
| James Willis Golf Ltd | Wholesale & retail | 2021 |
| Jamfred Ltd | Health & social care | 2021 |
| Jamie Cope Hair Limited | Other services | 2019 |
| Jamil Prestige Motors Ltd | Wholesale & retail | 2024 |
| Jamilla Strand Ltd | Administrative & support | 2020 |
| Jamrood Limited | Professional & scientific | 2024 |