| ISH Adaptive Agile Solutions Ltd | Manufacturing | 2018 |
| IT International Ltd. | Information & communication | 2016 |
| Ithelptv Ltd | Information & communication | 2020 |
| Iulgil Limited | Transport & logistics | 2018 |
| Ivab Ltd | Financial services | 2020 |
| J & D Flooring Services Ltd | Other services | 2018 |
| J E Earley Detailing Ltd | Construction | 2023 |
| J Professional Builders Limited | Construction | 2020 |
| J T Brannigan Construction Limited | Construction | 2017 |
| J Tesh NRA Limited | Professional & scientific | 2018 |
| J Wong Company Limited | Real estate | 2021 |
| J.A.S Lighthouse Limited | Education | 2014 |
| J.E.N Contract Services Ltd | Construction | 2018 |
| J7 Creative Limited | Professional & scientific | 2012 |
| JAL Jeevan UK Limited | Wholesale & retail | 2024 |
| JAM Golding Ltd | Real estate | 2025 |
| James Dodds Property Services Limited | Real estate | 2025 |
| Japan Core Competence Management Limited | Financial services | 2003 |
| Jato Assets Ltd | Construction | 2020 |
| Jazz Barbers 368 Ltd | Other services | 2026 |
| JBS Environmental Limited | Professional & scientific | 2012 |
| Jbvhomecontracts Ltd | Construction | 2022 |
| JC London Cleaning Services Limited | Administrative & support | 2018 |
| JCH Group Services Ltd | Administrative & support | 2025 |
| JCV Investments Ltd | Real estate | 2025 |
| JD Homes Developments Ltd | Real estate | 2025 |
| JD Homes London Ltd | Construction | 2022 |
| JE Healthcare Ltd | Health & social care | 2022 |
| Jeany Agbakoba Consulting Limited | Health & social care | 2016 |
| Jeneesa Property Ltd | Real estate | 2018 |
| Jervo Leasing Equipments Ltd | Administrative & support | 2024 |
| JH Legal Consulting Ltd | Professional & scientific | 2025 |
| Jilo House Limited | Education | 2021 |
| JK Rocha Services Ltd | Construction | 2022 |
| Jkan Business Solutions Limited | Professional & scientific | 2019 |
| JL Process Engineering Ltd | Professional & scientific | 2019 |
| Jlacs Ltd | Construction | 2025 |
| JLD South Ltd | Construction | 2023 |
| JNY Medical Ltd | Health & social care | 2025 |
| Joe's Heating and Plumbing Ltd | Construction | 2021 |
| Jogan Brewworks Ltd | Wholesale & retail | 2026 |
| JPM Holdings Group Ltd | Financial services | 2026 |
| JRP Security Ltd | Administrative & support | 2019 |
| JS Distribution London Limited | Wholesale & retail | 2024 |
| JSR Security Ltd | Administrative & support | 2024 |
| Jude House Management Company Ltd | Households | 2025 |
| Juice by Design Limited | Professional & scientific | 2002 |
| Junghee Limited | Real estate | 2024 |
| Just Move Mortgages Ltd | Financial services | 2021 |
| Juve Healthcare Ltd | Professional & scientific | 2022 |
| JVA Property Solutions Limited | Real estate | 2017 |
| JX Global Limited | Wholesale & retail | 2020 |
| JYL Consultancy Limited | Real estate | 2016 |
| K Vision Centre Ltd | Wholesale & retail | 2021 |
| Kabanalytics Ltd | Information & communication | 2025 |
| Kabba Conteh Limited | Health & social care | 2022 |
| Kachubira Cleaning Ltd | Administrative & support | 2025 |
| Kainth Management Ltd | Extraterritorial | 2014 |
| Kalin Limited | Construction | 2016 |
| Kalligraafik Ltd | Arts & recreation | 2020 |
| Kams Health Enterprises Limited | Health & social care | 2023 |
| Kanha Solutions Ltd | Professional & scientific | 2016 |
| Karina Patel Ltd | Health & social care | 2015 |
| Kate Hoare Counselling Ltd | Health & social care | 2024 |
| Kay's Homes & Gardens Ltd | Administrative & support | 2020 |
| Keith Savory Mechanical Services Ltd | Construction | 2012 |
| Kelea Contractors Limited | Construction | 2025 |
| Kellys Construction Solutions Ltd | Construction | 2022 |
| Kenet Holding Limited | Financial services | 2017 |
| Kenneth KC Consultancy Limited | Professional & scientific | 2021 |
| Kester Resources Ltd | Construction | 2015 |
| Keynote Consulting Ltd | Professional & scientific | 2025 |
| Keytake Limited | Real estate | 1989 |
| Khalij Food Centre Limited | Wholesale & retail | 2025 |
| Kherani Property Investments Ltd | Real estate | 2019 |
| Kherani Services Limited | Administrative & support | 2018 |
| Kick Central Ltd | Arts & recreation | 2024 |
| Kika Carpentry Ltd | Manufacturing | 2022 |
| Killester Limited | Information & communication | 2023 |
| Kindleworld Ltd | Arts & recreation | 2025 |
| King's Revival Church (Intl) Ministries | Other services | 2012 |
| Kingston Design & Build Ltd | Construction | 2025 |
| Kingston Huan Limited | Professional & scientific | 2012 |
| Kingston Makers Limited | Real estate | 2025 |
| Kinitic Limited | Information & communication | 2008 |
| Kipps & Co Legal Ltd | Professional & scientific | 2020 |
| KIT Hoang Ltd | Information & communication | 2020 |
| KK UK Investments Ltd | Real estate | 2017 |
| Kknp Property Ltd | Real estate | 2021 |
| KL Property Ltd | Real estate | 2019 |
| Klas Projects Limited | Construction | 2019 |
| KLS Data Ltd | Administrative & support | 2014 |
| KMG UK Property Ltd | Real estate | 2024 |
| Knatlus Ltd. | Wholesale & retail | 2024 |
| KNG Resolve Ltd | Construction | 2023 |
| Komodo Consulting Limited | Professional & scientific | 2019 |
| Kompass Racquet Sports Limited | Information & communication | 2025 |
| KOS Solutions Limited | Professional & scientific | 2015 |
| Kovalski Ltd | Wholesale & retail | 2026 |
| KP Plastering Limited | Construction | 2007 |