| Jewels Property Limited | Real estate | 2026 |
| JF Site Services Ltd | Construction | 2020 |
| JHS Healthcare and Aesthetics Limited | Health & social care | 2025 |
| Jigsaw Associates Limited | Professional & scientific | 2024 |
| Jigsaw Curated Events Ltd | Other services | 2026 |
| Jigsaw Holdings and Investments Ltd | Financial services | 2025 |
| Jigsaw Property Services (WM) Ltd | Real estate | 2021 |
| Jimmy JO Ltd | Wholesale & retail | 2022 |
| Jimmy Trims BH Ltd | Other services | 2018 |
| Jimmy Trims OW Ltd | Other services | 2018 |
| Jimmys House Limited | Real estate | 2014 |
| Jinnaga Ltd | Wholesale & retail | 2018 |
| Jitro Administration Ltd. | Financial services | 2013 |
| Jiyas Closet Ltd | Wholesale & retail | 2026 |
| JJE Supermarket Limited | Wholesale & retail | 2019 |
| Jjflick Ltd | Hospitality | 2022 |
| JKS Business Ltd | Real estate | 2022 |
| JL Electrical Ltd | Construction | 2023 |
| JLH Construction Midlands Ltd | Construction | 2024 |
| JLH Holdings and Investments Ltd | Financial services | 2024 |
| JLR Care Services Ltd | Health & social care | 2022 |
| JLS Holdings and Investments Ltd | Financial services | 2024 |
| JLS Installations Ltd | Construction | 2021 |
| JLV Global Ltd | Wholesale & retail | 2025 |
| Jlxem Limited | Wholesale & retail | 2022 |
| JM Engineering Midlands Ltd | Construction | 2024 |
| JM Property Trowbridge Ltd | Construction | 2025 |
| Jmcl Ltd | Real estate | 2025 |
| JMJ Recruitment Ltd | Education | 2022 |
| Jmm-Driver Limited | Transport & logistics | 2024 |
| Jmmr Limited | Manufacturing | 2008 |
| JMS Ground Services UK Ltd | Financial services | 2018 |
| JNI Barber Limited | Other services | 2025 |
| JNR Refurbs Ltd | Construction | 2024 |
| Jo&Jacob Services Limited | Health & social care | 2021 |
| Jobeky Drums Limited | Wholesale & retail | 2006 |
| Jobsby Ltd | Administrative & support | 2026 |
| Johannes Ltd | Transport & logistics | 2026 |
| John Buckley(Dudley)Limited | Manufacturing | 1909 |
| John Farney Tarmacadam Contractors Limited | Construction | 2022 |
| John Green Family Butchers Limited | Wholesale & retail | 2003 |
| John L Davis Consultancy Limited | Other services | 2022 |
| John Nolan Facades Limited | Construction | 2014 |
| John Whitehouse Limited | Construction | 2019 |
| Johnsons Consultancy Ltd | Construction | 2025 |
| Joinery & Timber Supplies Limited | Professional & scientific | 2016 |
| Jones & Jones Development Ltd | Real estate | 2019 |
| Jones Biomas Limited | Energy | 2017 |
| Jonge Poerink Limited | Manufacturing | 1964 |
| Joro Global Ltd | Administrative & support | 2025 |
| Josoro Ltd | Information & communication | 2025 |
| Jowett Smith Properties Limited | Real estate | 2017 |
| Joy and Co. Hair Ltd | Other services | 2022 |
| Joybuy Property Ltd | Real estate | 2025 |
| JP Convenience Ltd | Wholesale & retail | 2025 |
| JP Event Safety Ltd | Administrative & support | 2015 |
| JP Investment Group Ltd | Financial services | 2025 |
| JPB Cottages Ltd | Hospitality | 2020 |
| JPC Safety Limited | Administrative & support | 2023 |
| JPH & SON Electrics Limited | Construction | 2025 |
| JPJ Creative Investments Ltd | Financial services | 2019 |
| JPK Housing Ltd | Real estate | 2025 |
| JPS Plumbing Ltd. | Construction | 2009 |
| JRG Eco Electrics Limited | Construction | 2024 |
| Jrputt Holding Limited | Financial services | 2026 |
| JRS Holdings & Investments Ltd | Financial services | 2026 |
| JS Ehhd Holdings Ltd | Financial services | 2026 |
| JS Express Vehicle Movements Limited | Transport & logistics | 2025 |
| JS Invest Holdings Ltd | Real estate | 2021 |
| JSH Packaging Services Limited | Professional & scientific | 2025 |
| JT Autos Midlands Ltd | Wholesale & retail | 2025 |
| JT Civil Engineering Ltd | Construction | 2014 |
| JT Construct Limited | Construction | 2025 |
| Jubilee Court Care Home Limited | Administrative & support | 2017 |
| Jubilee Personnel Services Limited | Administrative & support | 2003 |
| Juke Visuals Limited | Professional & scientific | 2024 |
| Jukes Electrical Services Ltd | Construction | 2026 |
| Jula Finance Ltd | Financial services | 2011 |
| Julie Baker Limited | Health & social care | 2023 |
| Julius Bahn Ltd | Construction | 2013 |
| Jumping Jo's Day Nursery Limited | Health & social care | 2014 |
| Jumpz Ltd. | Administrative & support | 2017 |
| Jungle Jerky Limited | Manufacturing | 2025 |
| Junis Investments Limited | Real estate | 2025 |
| Junool Limited | Professional & scientific | 2026 |
| Jupp Air LLP | | 2002 |
| JUS Care Limited | Health & social care | 2020 |
| Just Have Soul Clothing Limited | Wholesale & retail | 2020 |
| Just Joy Hairdressing Ltd | Other services | 2018 |
| Just US Care Limited | Health & social care | 2016 |
| Jvin Rise Services Limited | Professional & scientific | 2023 |
| JW Business Lending Solutions Limited | Education | 2023 |
| JW Personal Training Holdings Ltd | Financial services | 2024 |
| JW Staircase Specialist Ltd | Construction | 2025 |
| JWB Holdings & Investments Ltd | Financial services | 2026 |
| JWS Repairs Limited | Wholesale & retail | 2010 |
| K & M Homes Limited | Construction | 2006 |
| K & M Partnership Ltd | Wholesale & retail | 2025 |
| K a Catering Limited | Manufacturing | 2017 |
| K Ahmed Consultancy Limited | Professional & scientific | 2010 |