| JJ Accounting and Consultancy Limited | Professional & scientific | 2023 |
| JJ Building Supplies Limited | Wholesale & retail | 2024 |
| JJ Electrical Security Limited | Construction | 2018 |
| JJ Haulage Hiab Ltd | Transport & logistics | 2014 |
| JJB Electrical Ltd | Construction | 2016 |
| JJG Property Development Ltd | Real estate | 2026 |
| JJK Bathrooms Ltd | Construction | 2025 |
| JJKOSI25 Limited | Health & social care | 2017 |
| JK Plumbing & Bathrooms Ltd | Construction | 2022 |
| JK Property Services Ltd | Real estate | 2022 |
| Jkal Properties Limited | Real estate | 2020 |
| JL Prop Developments Ltd | Construction | 2023 |
| JL Real Estate Group Ltd | Real estate | 2025 |
| Jlgm Limited | Real estate | 2024 |
| JLJ Property Limited | Real estate | 2025 |
| JLK Air Conditioning Limited | Construction | 2006 |
| JLN Property Limited | Construction | 2024 |
| JM Installations Ltd | Construction | 2021 |
| JM Roofworks Ltd | Construction | 2014 |
| JMC Construction 4UK Limited | Construction | 2019 |
| Jmjoseph Ltd | Professional & scientific | 2025 |
| JMS Gold Ltd | Wholesale & retail | 2019 |
| JNM Industries Ltd | Real estate | 1995 |
| Joanne Noonan Limited | Real estate | 2010 |
| Jobexa Limited | Information & communication | 2026 |
| JOE Saul-Baylis Ltd | Real estate | 2024 |
| Joeramass Domiciliary Care Limited | Health & social care | 2023 |
| Joeramass Semi Independent Living Ltd | Health & social care | 2022 |
| John Hughes Limited | Arts & recreation | 1996 |
| Johnstone Estates Limited | Real estate | 2023 |
| Johnstone Investments Limited | Real estate | 2019 |
| Joint Equity Limited | Real estate | 2003 |
| Joint Equity Partnership NO 10 LLP | | 2009 |
| Jolly Candy Ltd | Wholesale & retail | 2024 |
| Jonquilles Consulting Ltd | Information & communication | 2015 |
| Joral Ltd | Health & social care | 2016 |
| Jordan V a Services Limited | Manufacturing | 2013 |
| Jorgensen AM Consulting Ltd | Professional & scientific | 2025 |
| Joseph Mydell Limited | Information & communication | 2025 |
| Joseph Services & Solutions Ltd | Transport & logistics | 2011 |
| Jothbel Care Services Limited | Health & social care | 2019 |
| Jounak Complex Care Limited | Health & social care | 2025 |
| Joy Bangla Limited | Hospitality | 2002 |
| Joy Supply Chain Advisors Ltd | Information & communication | 2026 |
| JP Asset Investments Ltd | Financial services | 2023 |
| JP Properties Management Ltd | Real estate | 2021 |
| JP100 Ltd | Households | 2025 |
| Jpbpropertyservices Ltd | Real estate | 2024 |
| JPG Cctv & Electrical Limited | Other services | 2014 |
| JPG Cctv Group Limited | Other services | 2023 |
| JPI Investments Limited | Administrative & support | 2017 |
| JR Recruitment Solutions Limited | Administrative & support | 2024 |
| JRM Fencing Ltd | Construction | 2024 |
| JSG Metals Ltd | Wholesale & retail | 2011 |
| JSN Connect UK Limited | Financial services | 2023 |
| JT Healthcare Solutions Ltd | Other services | 2015 |
| JTT Events Limited | Arts & recreation | 2018 |
| Juma Holding Limited | Financial services | 2025 |
| Jump Design and Print Limited | Manufacturing | 2010 |
| Jump Estates Limited | Real estate | 2016 |
| Jump Group Limited | Information & communication | 2017 |
| Jump Wales Group Ltd | Financial services | 2022 |
| Junction 26 Truck Stop Limited | Wholesale & retail | 2020 |
| JUP Properties Ltd | Real estate | 2021 |
| Jurcom UK Ltd | Wholesale & retail | 2025 |
| Jurichez Limited | Health & social care | 2011 |
| Just Because Care Ltd | Hospitality | 2025 |
| Just Meat & Poultry Ltd | Wholesale & retail | 2019 |
| Just SIM Limited | Information & communication | 2016 |
| Juvetti Limited | Wholesale & retail | 2021 |
| JV Recycling Limited | Water & waste | 2015 |
| JV Shipping Limited | Administrative & support | 2001 |
| JVM Legal Services Limited | Professional & scientific | 2020 |
| JVR Railway Ltd | Construction | 2019 |
| Jvsat Ltd | Construction | 2026 |
| Jycourt Limited | Real estate | 2014 |
| Jyoti Property Group Ltd | Real estate | 2021 |
| K & K UK Marketing Services Ltd | Other services | 2011 |
| K 2 K Developments Limited | Construction | 2013 |
| K&M Commercials Ltd | Wholesale & retail | 2025 |
| K&M Street Food Ltd | Hospitality | 2025 |
| K.R.W. Limited | Hospitality | 2001 |
| K100 Properties Limited | Financial services | 2025 |
| KA Hospitality Limited | Construction | 2024 |
| Kaci Trading Ltd | Wholesale & retail | 2020 |
| Kadir Property Ltd | Real estate | 2025 |
| Kafli Tepe Limited | Education | 2020 |
| Kalvin Tyre Services Limited | Wholesale & retail | 2022 |
| KAM Universal Ltd | Real estate | 2024 |
| Kamal Farms Limited | Agriculture & fishing | 2026 |
| Kamox Resin Ltd | Administrative & support | 2025 |
| Kaner Group UK Ltd | Financial services | 2024 |
| Kaner Hospitality Limited | Hospitality | 2025 |
| Kaner SPV Limited | Real estate | 2024 |
| Kaos Technology Ltd | Professional & scientific | 2019 |
| Karaca Fresh Food Ltd | Wholesale & retail | 2025 |
| Karaca Holding Limited | Financial services | 2025 |
| Karaca IP Limited | Real estate | 2021 |
| Karikuna Ltd | Hospitality | 2023 |
| Karnas Property Services Ltd | Construction | 2021 |