| JM Event Hire Limited | Administrative & support | 2022 |
| JMG PVT Ltd | Wholesale & retail | 2021 |
| JMS Developers Ltd | Real estate | 2025 |
| Jnaa Ltd | Information & communication | 2023 |
| JO SFM Ltd | Administrative & support | 2012 |
| Jobtrolley Ltd | Information & communication | 2013 |
| Johal Architectural Fabrications Ltd | Construction | 2009 |
| John Guilding Software Development Ltd | Information & communication | 2022 |
| John Lester Wigs Ltd | Other services | 2023 |
| John Luthers Ltd | Construction | 2013 |
| John Torz Ltd | Construction | 2018 |
| Joizzy Enterprises Ltd | Health & social care | 2023 |
| Jolatech Ltd | Information & communication | 2025 |
| Jonadel Automobiles UK Limited | Wholesale & retail | 2017 |
| Jonce Consulting Limited | Administrative & support | 2012 |
| Josiah GLB Ltd | Construction | 2026 |
| JOT Propertes PVT Limited | Real estate | 2023 |
| Joyce Healthcare Ltd | Health & social care | 2023 |
| Joyfultex Ltd | Health & social care | 2015 |
| JP Berries Ltd | Wholesale & retail | 2025 |
| JPH Facilities and Maintenance Ltd | Construction | 2022 |
| JPS Interiors Limited | Construction | 2012 |
| Jr's Immortal Empire Limited | Other services | 2025 |
| JRJ Solutions Ltd | Construction | 2012 |
| Jsilver Events & Entertainment Ltd | Administrative & support | 2014 |
| Jsilver Events Limited | Administrative & support | 2018 |
| Jssb Investments Ltd | Other services | 2020 |
| Jtst Consultants Limited | Administrative & support | 2013 |
| Jucan Logistics Ltd | Transport & logistics | 2016 |
| Jugg London Limited | Wholesale & retail | 2019 |
| JUK Solutions Limited | Real estate | 2025 |
| Julian Fire Protection Ltd | Other services | 2019 |
| Julie's Little Angels Limited | Education | 2010 |
| Jumla Ltd | Wholesale & retail | 2019 |
| Just Drinks London Ltd | Wholesale & retail | 2021 |
| Just Seafood Ltd | Wholesale & retail | 2024 |
| Justbundleslondon Ltd | Wholesale & retail | 2021 |
| Justyres Ltd | Wholesale & retail | 2018 |
| Jweservices Ltd | Professional & scientific | 2020 |
| JWP London Ltd | Education | 2016 |
| K & R Cleaning Limited | Administrative & support | 2003 |
| K Tutors Limited | Education | 2014 |
| K&A Express Ltd | Transport & logistics | 2019 |
| K&L Carpentry Ltd | Construction | 2022 |
| Kaaf Enterprises Ltd | Wholesale & retail | 2025 |
| Kaaiz Ltd | Wholesale & retail | 2025 |
| Kaami Logistics London Ltd | Transport & logistics | 2026 |
| Kaboat Ltd | Construction | 2024 |
| Kadder Cleaning Services Limited | Construction | 2023 |
| Kagdil TN Ltd | Administrative & support | 2019 |
| Kahnaaf HT Ltd | Transport & logistics | 2022 |
| Kahonoki Properties Ltd | Real estate | 2025 |
| KAI Care Services Ltd | Health & social care | 2014 |
| Kaiconnectionslondon Ltd | Administrative & support | 2016 |
| Kailash Double Glazing Ltd | Manufacturing | 2020 |
| Kald Accountancy Ltd | Professional & scientific | 2025 |
| Kalem Cafe Ltd | Hospitality | 2024 |
| Kalind Ltd | Real estate | 2020 |
| Kalosplus Properties Limited | Real estate | 2022 |
| Kaluk Group Ltd | Construction | 2024 |
| Kamdjo Ltd | Construction | 2019 |
| Kamm Consultants Limited | Information & communication | 2008 |
| Kamshah Limited | Wholesale & retail | 2012 |
| Kane Solutions Ltd | Information & communication | 2021 |
| KAR 25 Limited | Hospitality | 2025 |
| Kara Luna Ltd | Real estate | 2025 |
| Karabosha Ltd | Education | 2013 |
| Kargolink Ltd | Wholesale & retail | 2024 |
| Katella Properties Company Limited | Construction | 1984 |
| Katstan Transport Ltd | Transport & logistics | 2014 |
| KAY GEE Management Limited | Real estate | 2021 |
| Kayamatrix Limited | Information & communication | 2024 |
| Kayjay Consultancy Ltd | Professional & scientific | 2018 |
| Kayk Enterprise Ltd | Other services | 2017 |
| Kays Limited Limited | Health & social care | 2016 |
| Kayzee Treats Ltd | Wholesale & retail | 2022 |
| KAZ Foods Ltd | Wholesale & retail | 2020 |
| Kbrc Associates Limited | Real estate | 2010 |
| KDD Construction Ltd. | Construction | 2012 |
| KDD Motors Ltd | Wholesale & retail | 2022 |
| Kebabish Extra Ltd | Hospitality | 2022 |
| Keeble Group Ltd | Administrative & support | 1951 |
| KEG Line Control Systems Ltd | Administrative & support | 2010 |
| Kemjog Limited | Health & social care | 2016 |
| Kent Regalia Limited | Wholesale & retail | 2025 |
| Keonkay Events Security Ltd | Administrative & support | 2025 |
| Kerilin Ltd | Information & communication | 2010 |
| Kevin Car Sale & HCW Ltd | Wholesale & retail | 2021 |
| Key in Ltd | Other services | 2012 |
| Keystone Educational Services Ltd | Education | 2019 |
| Keystone Property and Development UK Ltd | Real estate | 2024 |
| Kfts Solutions Ltd | Information & communication | 2019 |
| KG Films Production Ltd | Information & communication | 2023 |
| KG Magic Repairs Ltd | Construction | 2016 |
| Kgworkforce Ltd | Construction | 2019 |
| Kharis House Ltd | Hospitality | 2020 |
| Kharis Residential Home Ltd | Health & social care | 2016 |
| Khatija Enterprise Ltd | Transport & logistics | 2024 |
| Khatun Takeaway Ltd | Hospitality | 2025 |
| Khma Properties Limited | Real estate | 2025 |