| Jp&H Specialists Ltd | Construction | 2022 |
| JPC Projects Ltd | Construction | 2019 |
| Jplife Estates UK Limited | Real estate | 2025 |
| JPM Finance Limited | Financial services | 2023 |
| JR Clean London Limited | Administrative & support | 2025 |
| Jrft Holdings Ltd | Real estate | 2026 |
| Jrsp Home Ltd | Health & social care | 2026 |
| Jsbc Properties Ltd | Real estate | 2019 |
| JTR Security Systems Ltd | Administrative & support | 2015 |
| JTS Holiday Camps Ltd | Education | 2021 |
| Jubilee Landscaping Ltd | Administrative & support | 2022 |
| Judge Venetian Plastering Ltd | Construction | 2025 |
| Juicegrid Limited | Construction | 2025 |
| Julian Storey Aviation Limited | Wholesale & retail | 2013 |
| Julieta Camino Limited | Health & social care | 2025 |
| Jurtrans Translations Ltd | Professional & scientific | 2012 |
| Just East Limited | Transport & logistics | 2022 |
| Just US Girls Global Network Limited | Other services | 2022 |
| JUSTBE4U CIC | Health & social care | 2019 |
| Justice Catering Limited | Hospitality | 2014 |
| Juve Limited | Real estate | 1986 |
| JVG Interiors Limited | Construction | 2017 |
| JXH Developments Limited | Real estate | 2016 |
| K Crozier Heating Limited | Construction | 2015 |
| K J Lennard Limited | Administrative & support | 2010 |
| K Norman Accountancy Solutions Limited | Professional & scientific | 2017 |
| K Stark Ltd | Construction | 2016 |
| K&B Used Cars Sales Limited | Wholesale & retail | 2024 |
| K&G Assets Ltd | Real estate | 2022 |
| K&N International Limited | Professional & scientific | 2024 |
| K.C.P. Computer Services Limited | Information & communication | 1981 |
| K.S.B. Electrical Limited | Construction | 1997 |
| KA Crystal Services Limited | Administrative & support | 2025 |
| Kabashi Holdings Limited | Real estate | 2017 |
| Kaizen AI Limited | Information & communication | 2025 |
| Kalivarathan Global Ventures Ltd | Manufacturing | 2025 |
| Kalomo Limited | Professional & scientific | 2024 |
| Kamilla Jones Ltd | Manufacturing | 2017 |
| Kandi & Co Consultants Ltd | Professional & scientific | 2019 |
| Kandiah Courier Company Ltd | Transport & logistics | 2019 |
| Kanisirin Property Limited | Real estate | 2026 |
| KAP Investment Group Ltd | Real estate | 2025 |
| Kapoor Chemists Limited | Wholesale & retail | 2004 |
| Kaps London Limited | Real estate | 2020 |
| Karakocan Fish & Kebab Ltd | Hospitality | 2024 |
| Karakter Worldwide Ltd | Administrative & support | 2006 |
| Kararo Property Limited | Real estate | 2020 |
| Karim Services Ltd | Administrative & support | 2026 |
| Karli Properties Limited | Real estate | 2022 |
| Kasimpasa Limited | Hospitality | 2026 |
| Kataria Endodontics Ltd | Health & social care | 2018 |
| Kate England Therapy Limited | Health & social care | 2021 |
| Kavatina Limited | Real estate | 1971 |
| Kavi Take Away Limited | Hospitality | 2024 |
| KAY Holdings Ltd | Real estate | 2018 |
| Kayem Media Ltd | Professional & scientific | 2024 |
| Kaylesh Consulting Ltd | Professional & scientific | 2019 |
| KB Motor Services Ltd | Wholesale & retail | 2018 |
| KB Pro Services Ltd | Administrative & support | 2025 |
| KC Courier Express Ltd | Transport & logistics | 2025 |
| KD Film Productions Ltd | Arts & recreation | 2023 |
| KD Traders Ltd | Wholesale & retail | 2023 |
| Keaneys Limited | Construction | 2004 |
| Kearns Actuarial Ltd | Financial services | 2023 |
| Kebab Express Catering Limited | Hospitality | 2025 |
| Kebaby Ltd | Extraterritorial | 2012 |
| Keiki Bakes Ltd | Hospitality | 2025 |
| Keith Brooker Property Services Limited | Construction | 2022 |
| Kekova Food Limited | Hospitality | 2017 |
| Keky Finance & Accounts Ltd | Professional & scientific | 2019 |
| Kelechi Dylan Enterprise Ltd | Construction | 2021 |
| Kelicomp Computing Limited | Information & communication | 1990 |
| Kelly Maternus Ltd | Wholesale & retail | 2024 |
| Kelroi Limited | Information & communication | 2018 |
| Kelvinosagie Ltd | Health & social care | 2019 |
| Kendra Court Residents Limited | Households | 2004 |
| Kendra Freehold Limited | Households | 2022 |
| Kens Autos Godstone Road Limited | Wholesale & retail | 2015 |
| Kens Autos Warlingham Limited | Wholesale & retail | 2014 |
| Kent Estate Mgmt Limited | Real estate | 2019 |
| Keplerware Ltd | Information & communication | 2020 |
| Keralu Ltd | Hospitality | 2020 |
| KEV Sourcing Ltd | Wholesale & retail | 2024 |
| Keval Shah Audio Limited | Information & communication | 2025 |
| Kevan Enterprise Ltd | Hospitality | 2026 |
| Kevin Hewitt Ltd | Information & communication | 2007 |
| Key One Services Ltd | Construction | 2019 |
| Key Shift London CIC | Information & communication | 2024 |
| Keymall Property Management Limited | Households | 1989 |
| Khana Enterprise Ltd | Hospitality | 2025 |
| Khans of London Ltd | Wholesale & retail | 2026 |
| Khiavi Consultancy Ltd | Professional & scientific | 2025 |
| Khoob Properties Ltd | Real estate | 2019 |
| Kibris Amerikan Hastahanesi Limited | Extraterritorial | 2013 |
| Kibris Turk Havayollari Limited | Extraterritorial | 2014 |
| Kidibelete Limited | Manufacturing | 2020 |
| Kids Vogue Stars Ltd | Arts & recreation | 2017 |
| KIE Housing and Support Limited | Hospitality | 2014 |
| Kilian Garden Company Limited | Professional & scientific | 2001 |
| Kinderland Day Nursery Limited | Education | 2003 |