| JK Scaffolding Services Ltd | Construction | 2020 |
| JM Faboya Ltd | Wholesale & retail | 2025 |
| JMP Plumbing & Electrical Services Ltd | Construction | 2015 |
| JMP Plumbing Services Ltd | Construction | 2016 |
| JMP Property Ventures Ltd | Real estate | 2025 |
| JNL Car Wash Boutique Ltd | Wholesale & retail | 2025 |
| Joel Property Maintenance Ltd | Households | 2023 |
| John Brown & Co Estate Agents Ltd | Real estate | 2021 |
| John Lane Consulting Limited | Construction | 2015 |
| John MAY (Tobacco) | Real estate | 1962 |
| Jolt Consulting Limited | Information & communication | 2010 |
| JON WU Ltd | Health & social care | 2011 |
| Jordan Music Workshops Limited | Education | 2011 |
| Jordanglia Ltd | Professional & scientific | 2014 |
| Josiah Paull DIW Limited | Mining & quarrying | 2026 |
| Josiah Paull Onen Limited | Mining & quarrying | 2026 |
| JPA Plumbing & Heating Services Ltd | Construction | 2008 |
| JPD Technical Services Ltd | Professional & scientific | 2020 |
| JPH Electrics Limited | Construction | 2012 |
| JPL Westwood Consulting Ltd | Health & social care | 2020 |
| JPM Freelance Limited | Administrative & support | 2022 |
| JPN Shipping Ltd | Transport & logistics | 2009 |
| Jrapha Enterprises Ltd | Health & social care | 2010 |
| JRB International Ltd | Health & social care | 2020 |
| JSL D-B Ltd | Public administration | 2016 |
| Jume Ltd | Wholesale & retail | 2025 |
| Junction 7 Consulting Limited | Administrative & support | 2018 |
| Junction 7 Developments Limited | Construction | 2014 |
| Junction 7 Electrical Limited | Administrative & support | 2005 |
| Junction 7 Group Limited | Construction | 2015 |
| Junction 7 Investments Limited | Construction | 2014 |
| Junction 7 Limited | Construction | 2016 |
| Junction 7 Residential Limited | Real estate | 2018 |
| Jung Personal Mastery Ltd | Professional & scientific | 2022 |
| Just Ace T/A Airport Xpress Cars Limited | Transport & logistics | 2020 |
| Just Before Courtship/Marriage (JB4) | Information & communication | 2013 |
| Just Caring Hands Limited | Health & social care | 2019 |
| Just the Ticket Ltd. | Professional & scientific | 2025 |
| Just Worx Ltd | Construction | 2020 |
| Justte Property Limited | Real estate | 2018 |
| Jvhumedical Limited | Health & social care | 2025 |
| K B Lounge Limited | Other services | 2018 |
| K VEG Wholesale Limited | Wholesale & retail | 2006 |
| K Zebu Limited | Wholesale & retail | 2021 |
| K&A Essentials Limited | Wholesale & retail | 2023 |
| K. LAM Executive Support Ltd | Administrative & support | 2026 |
| K.A.L. Snipe Consulting Ltd | Administrative & support | 2025 |
| K.E Broadcast Ltd | Information & communication | 2018 |
| K2 Group Ltd | Real estate | 2020 |
| K2-UK Limited | Information & communication | 2013 |
| Kabod Property Limited | Real estate | 2020 |
| Kadkore Ltd | Real estate | 2021 |
| Kainat Ltd | Wholesale & retail | 2022 |
| Kaip Habitat Limited | Real estate | 2024 |
| Kaizenkin Properties Ltd | Real estate | 2025 |
| Kajetha Limited | Real estate | 2020 |
| Kalai Tech Limited | Information & communication | 2017 |
| Kalogroulis Design Ltd | Professional & scientific | 2007 |
| Kanaga & Kenstein Ltd | Real estate | 2018 |
| Kaniyamiran Ltd | Hospitality | 2026 |
| Kara Dwellings Ltd | Real estate | 2017 |
| Karim Medicare Ltd | Health & social care | 2013 |
| Kaynaya Limited | Households | 2025 |
| Keecraft Ltd | Manufacturing | 2021 |
| Keeley Nursery Limited | Education | 2010 |
| Keemac Construction Limited | Construction | 2013 |
| KEF Partners Limited | Hospitality | 2024 |
| Keitc LLP | | 2019 |
| Keitco Ltd | Real estate | 2018 |
| Keith Contracting UK Limited | Professional & scientific | 2004 |
| Kendora Healthcare Limited | Administrative & support | 2020 |
| Kenitos Coulsdon Ltd | Hospitality | 2024 |
| Kens Electrical & Property Services Limited | Construction | 2009 |
| Kensho Estates Ltd | Real estate | 2021 |
| Kensho Media Limited | Professional & scientific | 2011 |
| Kensho Venture Limited | Financial services | 2024 |
| Keston Project Planning Ltd | Construction | 2026 |
| Keviko Ltd | Information & communication | 2015 |
| Kevin AGS Ltd | Professional & scientific | 2021 |
| Keylinks Serviced Accommodation Ltd | Hospitality | 2019 |
| Keyquest Limited | Real estate | 2023 |
| Keystone Risk Consultancy Limited | Professional & scientific | 2021 |
| Keyview Properties Limited | Real estate | 2015 |
| Kgentertainments Ltd | Other services | 2012 |
| Khawaja Consulting Limited | Professional & scientific | 2024 |
| Khayri Ltd | Wholesale & retail | 2023 |
| KII Ltd | Construction | 2014 |
| KII Properties Ltd | Real estate | 2024 |
| Kimmy Beauty Limited | Wholesale & retail | 2023 |
| Kind Therapy Ltd | Health & social care | 2026 |
| Kingmade Limited | Information & communication | 2021 |
| Kingstonian FC Limited | Arts & recreation | 2002 |
| Kiran Manak Productions Limited | Information & communication | 2025 |
| Kiroro and SON Limited | Other services | 2017 |
| Kishanth Properties Ltd | Real estate | 2020 |
| Kizza Limited | Manufacturing | 2026 |
| KLH Property Services Limited | Construction | 2018 |
| Klobe Ltd | Real estate | 2019 |
| Kloud IO Platform Services Ltd | Information & communication | 2026 |
| KM Barbers Ltd | Other services | 2022 |