| JAP Performance Parts Limited | Wholesale & retail | 2005 |
| Japan Productions Ltd | Information & communication | 2024 |
| Jarratt Holdings Limited | Professional & scientific | 2016 |
| Jasmin Matharu Limited | Wholesale & retail | 2018 |
| Jason Cundy Sports Limited | Administrative & support | 2010 |
| Jaunelion Limited | Professional & scientific | 2013 |
| Jayanda Ltd | Professional & scientific | 2002 |
| Jaybee TV Limited | Information & communication | 2017 |
| Jayjay Medical Consultants Ltd | Health & social care | 2009 |
| JB Special Effects Ltd | Information & communication | 2019 |
| Jbfox Consultancy Limited | Administrative & support | 2016 |
| JC Digital & Ecom Labs Ltd | Wholesale & retail | 2025 |
| JCB Smart Limited | Wholesale & retail | 2025 |
| JD & JB Property Limited | Real estate | 2019 |
| JD James Limited | Information & communication | 2013 |
| JD Supermarket Limited | Wholesale & retail | 2008 |
| JDJ Investments Ltd | Real estate | 2017 |
| Jean Care Limited | Health & social care | 2021 |
| Jeanette Court Management Company Limited | Households | 2004 |
| Jeat Consulting Limited | Information & communication | 2017 |
| JEE LOK Limited | Hospitality | 2022 |
| JEH Electricians Ltd | Construction | 2019 |
| Jersey Road Osterley Residents Limited | Households | 1995 |
| Jeune Hair & Beauty Clinic Ltd | Other services | 2018 |
| JG9 Services Limited | Professional & scientific | 2018 |
| Jhsmart Limited | Wholesale & retail | 2019 |
| JHW Retail Ltd | Wholesale & retail | 2019 |
| Jibzy Limited | Real estate | 2025 |
| Jijel Hair and Beauty Ltd | Other services | 2016 |
| Jira Consulting Limited | Administrative & support | 2013 |
| JJ Partners & Co Ltd | Administrative & support | 2024 |
| JJR Isaac Properties Ltd | Real estate | 2020 |
| Jlsr Consultancy Ltd | Professional & scientific | 2024 |
| JM Property Consulting Ltd | Construction | 2016 |
| JMS Overseas Education Limited | Professional & scientific | 2020 |
| JMS Real Estate Holdings Limited | Real estate | 2025 |
| JNH IT Consulting Ltd | Information & communication | 2021 |
| JNT Property Limited | Real estate | 2018 |
| Joblinker Ltd | Administrative & support | 2026 |
| Jobreel Limited | Information & communication | 2024 |
| John Dawkins Associates Limited | Professional & scientific | 2015 |
| John TON Ltd | Construction | 2026 |
| JOHN1 1PROPERTIES Ltd | Real estate | 2022 |
| Johnny Gourmet Ltd | Wholesale & retail | 2025 |
| Johnny Moga Ltd | Health & social care | 2016 |
| Johnson Corporation Limited | Other services | 2019 |
| Johnson Research Limited | Professional & scientific | 2017 |
| Joie DE Vivre Accessories Ltd | Wholesale & retail | 2020 |
| Jome Interiors Ltd | Other services | 2022 |
| JON Carter Advisory Services Limited | Professional & scientific | 2025 |
| Josan Construction Services Ltd | Construction | 2018 |
| JP Vision Decors Ltd | Construction | 2022 |
| Jpxjpx Ltd | Administrative & support | 2017 |
| JRJ Vapes Limited | Wholesale & retail | 2010 |
| JS Sekhon Investments Limited | Real estate | 2021 |
| JS Worldwide Limited | Transport & logistics | 2017 |
| JSC STF Ltd | Wholesale & retail | 2024 |
| JSP Consultancy Limited | Professional & scientific | 2012 |
| Jubilee Service Centre Limited | Wholesale & retail | 2010 |
| Julius-Lac Construction Ltd | Construction | 2026 |
| JUS Grow UK Ltd | Agriculture & fishing | 2024 |
| Just Jacks Trading Ltd | Wholesale & retail | 2015 |
| Jvuk Property Ltd | Real estate | 2023 |
| JW Cline Road Limited | Construction | 2015 |
| JW Willesden Limited | Construction | 2014 |
| Jwsuk Limited | Wholesale & retail | 2023 |
| K & M Enterprises Limited | Wholesale & retail | 2010 |
| K D Brothers Ltd | Real estate | 2019 |
| K Wall Construction Limited | Construction | 2016 |
| K&A Delivery Ltd | Wholesale & retail | 2019 |
| K-Square Venture Limited | Real estate | 2023 |
| K2-18 Ltd | Information & communication | 1997 |
| K2P Property Investments Ltd | Real estate | 2018 |
| KA Advisory Co. Limited | Professional & scientific | 2026 |
| Kaamyaab Ltd | Education | 2021 |
| Kaizen Hospitality Ltd | Professional & scientific | 2019 |
| Kakori Ltd | Professional & scientific | 2012 |
| Kalam Consulting Limited | Professional & scientific | 2017 |
| Kalanabha Solutions Private Limited | Information & communication | 2021 |
| Kalcon Ltd | Real estate | 2015 |
| Kamen Pro Ltd | Construction | 2019 |
| Kamsam Properties Ltd | Real estate | 2026 |
| Kanchan Real Estate Ltd | Real estate | 2023 |
| Kannon GAS Ltd | Construction | 2021 |
| Kapoor Brothers Properties Ltd | Real estate | 2017 |
| Kapur Estates Ltd | Real estate | 2020 |
| Kapur Telco Limited | Wholesale & retail | 2018 |
| Karas Investments Ltd | Real estate | 2022 |
| Kardiovaskular Limited | Health & social care | 2013 |
| Karma Blue Ltd | Wholesale & retail | 2022 |
| Karte Parwan Ltd | Hospitality | 2025 |
| KAS Compliance Solutions Limited | Financial services | 2015 |
| Kashap Investments Limited | Real estate | 2021 |
| Kashmiri Inc. Ltd | Professional & scientific | 2024 |
| Kasia Gott Studio Ltd | Professional & scientific | 2022 |
| Kassel Media Ltd | Information & communication | 2019 |
| Kate Stenner Limited | Manufacturing | 2026 |
| Katherine Doyle Limited | Arts & recreation | 2008 |
| Kavi & Amber Properties Ltd | Real estate | 2018 |
| Kavitakhosla Ltd | Administrative & support | 2020 |