| JD Network Solutions Ltd | Information & communication | 2015 |
| Jdts Consultancy Limited | Professional & scientific | 2025 |
| Jekyll & Hide Ltd | Information & communication | 2024 |
| Jimmy's Kitchen & Catering Limited | Hospitality | 2019 |
| Jimmy's Lahori Dhaba Limited | Hospitality | 2020 |
| Jitha Limited | Information & communication | 2025 |
| Jjjj Ltd | Information & communication | 2023 |
| JL MIC Limited | Wholesale & retail | 2007 |
| JML Electrical Services Ltd | Administrative & support | 2016 |
| JMN Scenery Limited | Information & communication | 2022 |
| JOE Edwards Scenery Ltd | Information & communication | 2015 |
| Joe's Judo Limited | Arts & recreation | 2014 |
| John Miller Upholstery Limited | Other services | 2014 |
| Josy Davis and Associates Limited | Administrative & support | 1989 |
| Jowood Limited | Professional & scientific | 2023 |
| Jrsfx Limited | Information & communication | 2018 |
| Jubilee Centre Developments Limited | Extraterritorial | 2000 |
| Justonemore.Ok Limited | Real estate | 2025 |
| JW Virgo Services Ltd | Professional & scientific | 2023 |
| K a Medical Limited | Health & social care | 2007 |
| K&M Flavours Ltd | Hospitality | 2023 |
| K22 Limited | Information & communication | 2021 |
| Kanchana Productions Limited | Arts & recreation | 1978 |
| Karan Convenience Ltd | Wholesale & retail | 2026 |
| Karian Supply Consulting Ltd | Professional & scientific | 2021 |
| Kathryn Graham Advisory Limited | Administrative & support | 2023 |
| Kaye Cartwright Limited | Construction | 2010 |
| Kean Construction Limited | Manufacturing | 2025 |
| Kelly Close Management Company Limited | Households | 1983 |
| Kershawcopy Ltd | Professional & scientific | 2025 |
| Key Business Systems | | 1994 |
| Key Greens Landscapes Limited | Administrative & support | 2015 |
| Keyframe Creative Ltd | Information & communication | 2015 |
| Keyring Property Ltd. | Real estate | 2021 |
| Killer Sales Growth Limited | Information & communication | 2025 |
| Kingfisher Decking Limited | Administrative & support | 2021 |
| Kingfisher Scenery Ltd | Information & communication | 2019 |
| Kirenology Limited | Health & social care | 2021 |
| KLC Commercial Mortgages Ltd | Financial services | 2025 |
| Klondike Limited | Transport & logistics | 2017 |
| Knights Basketball Academy CIC | Arts & recreation | 2017 |
| Knights Basketball Limited | Education | 2016 |
| Kogitech Limited | Professional & scientific | 2017 |
| KPM Property Services Limited | Construction | 2006 |
| Kroonenburg Capital Ltd | Construction | 2023 |
| KS Teamwear Limited | Wholesale & retail | 2014 |
| Kulkarni Rathore Associates Ltd | Professional & scientific | 2020 |
| Kulkarni Rathore Investments Ltd | Real estate | 2024 |
| L S Displays Limited | Other services | 2008 |
| L.A. Ying Limited | Information & communication | 2015 |
| Lady and the Scruff Limited | Agriculture & fishing | 2024 |
| Lake Edge Investments Ltd | Real estate | 2021 |
| Laragan Testing Limited | Information & communication | 2014 |
| LAS Palmas Estates Limited | Extraterritorial | 1959 |
| Laughing PIG Limited | Professional & scientific | 2006 |
| Laura's Little Design Company Ltd | Administrative & support | 2016 |
| Laysons Limited | Wholesale & retail | 2021 |
| Lazernetworks Limited | Information & communication | 2020 |
| LBS (Staines) Limited | Wholesale & retail | 2003 |
| Leaf Project Management Limited | Professional & scientific | 2015 |
| Legacy Fitness Ltd | Arts & recreation | 2025 |
| Lenfield Group Limited | Construction | 2024 |
| Lenovo Consulting Limited | Information & communication | 2005 |
| LEO Ventures Consultants Ltd | Information & communication | 2025 |
| LGJ Associates Limited | Wholesale & retail | 2018 |
| LGS Tech Limited | Manufacturing | 2014 |
| Library Mews Limited | Administrative & support | 2013 |
| LIE BAO Ltd | Transport & logistics | 2019 |
| Life Events Management Ltd | Administrative & support | 2026 |
| Lincs Processed Metals Ltd | Wholesale & retail | 2025 |
| Lindon Lewis Marine Limited | Wholesale & retail | 1989 |
| Linkbuild Limited | Administrative & support | 2005 |
| Lion Close (Shepperton) Management Company Limited | Professional & scientific | 2004 |
| Little Glam Van Ltd | Other services | 2025 |
| Little Rock Design Limited | Other services | 2015 |
| Littletonsc Ltd | Arts & recreation | 2024 |
| Living Stone Plants (London) Limited | Other services | 2009 |
| LJW Consultancy Limited | Professional & scientific | 2014 |
| LOA Consultants Ltd | Mining & quarrying | 2015 |
| Local Roof Repairs UK Limited | Construction | 2025 |
| Lockside Business Limited | Manufacturing | 2024 |
| Logiclogicmagic Ltd | Professional & scientific | 2019 |
| London & Surrey Care Group Limited | Health & social care | 2020 |
| Lookfar Consulting Limited | Professional & scientific | 2024 |
| Loudman Services Ltd | Administrative & support | 2022 |
| LRD Building Specialists Limited | Construction | 2013 |
| Lscg Holdco Limited | Health & social care | 2019 |
| LSG Electrical Holdings Limited | Financial services | 2025 |
| LTR Services Limited | Construction | 2016 |
| Lucanu Construction Ltd | Construction | 2014 |
| Luda Meridian Ltd | Professional & scientific | 2015 |
| Lumen Learning Trust | Education | 2013 |
| Lumino London Limited | Wholesale & retail | 2024 |
| Lumley Project Services Ltd | Professional & scientific | 2018 |
| Lunardog Limited | Professional & scientific | 2008 |
| LY Technical Services Ltd | Manufacturing | 2015 |
| M & V Consultants Limited | Financial services | 2016 |
| M Bellamy Property Investments Ltd | Real estate | 2020 |
| M I Properties (Sunbury) Limited | Hospitality | 2004 |
| M S Project and Consulting Ltd | Information & communication | 2015 |