| J & S Goodman Ltd | Health & social care | 2016 |
| J a G Precision Limited | Manufacturing | 2018 |
| J a Neale Ltd | Professional & scientific | 2025 |
| J Alexander Consulting Limited | Professional & scientific | 2025 |
| J and B Links Limited | Construction | 2026 |
| J and M Roofing and Scaffolding Ltd | Construction | 2023 |
| J Betson Electrical Ltd | Construction | 2024 |
| J C Pursehouse Ltd | Agriculture & fishing | 2023 |
| J D Drainage Ltd | Water & waste | 2024 |
| J Daniels Building Ltd | Construction | 2019 |
| J F Ratcliff Farms Limited | Agriculture & fishing | 2019 |
| J F Smit 2 Ltd | Health & social care | 2022 |
| J Farmer Property Services Ltd | Manufacturing | 2026 |
| J Flatt Contracting Ltd | Agriculture & fishing | 2024 |
| J H Commercial Vehicle Services Ltd | Wholesale & retail | 2026 |
| J J M Tools Ltd | Wholesale & retail | 2015 |
| J J Patrick Limited | Information & communication | 2019 |
| J K Mayes Plumbing and Heating Limited | Construction | 2015 |
| J Kelsall Accountants Ltd | Professional & scientific | 2025 |
| J Macclinton Ltd | Hospitality | 2018 |
| J P Ladell Limited | Construction | 2001 |
| J Pedalboards Ltd | Manufacturing | 2025 |
| J R Aesthetics Gants Hill Ltd | Other services | 2018 |
| J R Elliott Ltd | Construction | 2010 |
| J S Location Services Limited | Information & communication | 2024 |
| J Simpson (Financial Management) Ltd | Professional & scientific | 2011 |
| J T Developments (Oswestry) Limited | Construction | 2016 |
| J Whelan Property Holdings Ltd | Real estate | 2023 |
| J&D Design Ltd | Professional & scientific | 2017 |
| J&H Bespoke Stays Ltd | Real estate | 2025 |
| J&J Builders London Ltd | Other services | 2024 |
| J&J Construction Heritage Ltd | Construction | 2024 |
| J&L Sanders Haulage Limited | Transport & logistics | 2012 |
| J&P Cleaning Ltd | Administrative & support | 2024 |
| J&S Accommodation Ltd | Hospitality | 2023 |
| J&T Accounting Limited | Professional & scientific | 2023 |
| J-Circuit Concept Ltd | Hospitality | 2023 |
| J-Dax Limited | Professional & scientific | 2017 |
| J-Sala Ltd. | Wholesale & retail | 2018 |
| J. Doring Limited | Manufacturing | 2024 |
| J. G. Cleaning Service Ltd | Administrative & support | 2009 |
| J. R. Stennett (Holdings) Limited | Financial services | 1990 |
| J.H. Design Services Ltd | Professional & scientific | 2018 |
| J.K.H.Drainage Units Limited | Manufacturing | 1969 |
| J.Karalius Ltd | Transport & logistics | 2025 |
| J.Kilinskas Limited | Transport & logistics | 2026 |
| J.P Vertical Horizon 4K Ltd | Professional & scientific | 2025 |
| J.P. Jesty Engineering Limited | Manufacturing | 2003 |
| J.R.Lee Consultants Limited | Professional & scientific | 2021 |
| J.W. Palmer Properties Limited | Real estate | 1965 |
| J3 Horizon Homes Ltd | Real estate | 2023 |
| J3N4KD Limited | Transport & logistics | 2017 |
| JA Mechanical & Electrical Ltd | Manufacturing | 2024 |
| JA3L Ltd | Wholesale & retail | 2025 |
| JAB Logistic Support Ltd | Transport & logistics | 2025 |
| Jabberwock Communications Ltd | Information & communication | 2019 |
| Jabu Designs Limited | Information & communication | 2011 |
| Jacara Property Ltd | Real estate | 2021 |
| Jack Alexander Ltd. | Wholesale & retail | 2021 |
| Jack Saint Ltd | Information & communication | 2022 |
| Jack Stephenson Btlp Ltd | Construction | 2025 |
| Jack Trading Limited | Wholesale & retail | 2024 |
| Jack's Shack Smokehouse Ltd | Hospitality | 2022 |
| Jacks Hydrogen Ltd | Wholesale & retail | 2026 |
| Jackson Anaesthesia Ltd | Health & social care | 2021 |
| Jackson Build Limited | Construction | 2024 |
| Jackson Cladding Ltd | Construction | 2025 |
| Jackson House Limited | Wholesale & retail | 2003 |
| Jackson Waite (Town & Country) Ltd. | Real estate | 2013 |
| Jackson Windows Holdings Limited | Financial services | 2026 |
| Jackson Windows Limited | Construction | 2026 |
| Jacqui Bourne Ltd | Professional & scientific | 2025 |
| Jacwil Ltd | Real estate | 2018 |
| Jagelo Haulage Limited | Transport & logistics | 2019 |
| Jagfitness Ltd | Wholesale & retail | 2017 |
| Jagjeet Holdings Ltd | Wholesale & retail | 2026 |
| Jagoapp Ltd | Information & communication | 2025 |
| Jahco (Battersea) Limited | Real estate | 2023 |
| Jahco Finance Limited | Financial services | 2017 |
| Jahco Investments Limited | Financial services | 2022 |
| Jahco Limited | Financial services | 2015 |
| Jajja Sells Ltd | Wholesale & retail | 2023 |
| Jakaya Ltd | Professional & scientific | 2024 |
| Jake Smith Limited | Construction | 2003 |
| JAM Analytics Limited | Professional & scientific | 2023 |
| JAM JAR Theatre Company CIC | Arts & recreation | 2024 |
| JAM Jewellery Agency Ltd | Wholesale & retail | 2024 |
| Jama Optics Ltd | Health & social care | 2019 |
| James Allum Plastering Limited | Construction | 2003 |
| James C Holding Ltd | Other services | 2026 |
| James John Ltd | Professional & scientific | 2021 |
| James Nicholl Consultant LLP | | 2013 |
| James Reinman Marine Limited | Manufacturing | 1997 |
| James Waters Limited | Construction | 2003 |
| Jamila Lions Limited | Real estate | 2025 |
| Jamison Consulting Limited | Professional & scientific | 2018 |
| Jamjar Storage Ltd | Wholesale & retail | 2021 |
| Jamrock Restaurant & Bar Limited | Hospitality | 2008 |
| Jamsparkx Limited | Construction | 2019 |
| Jane Cappleman Interior Design Limited | Administrative & support | 2012 |