| Jose Healthcare Company Limited | Health & social care | 2022 |
| Josh Evans Ltd | Education | 2013 |
| Josh Security Services Ltd | Professional & scientific | 2020 |
| Joy of Taste Ltd | Health & social care | 2010 |
| JPP Aviation Services Ltd | Transport & logistics | 2013 |
| JPS Consulting and Property Ltd | Real estate | 2017 |
| JPS Programming Ltd | Professional & scientific | 2025 |
| JR Events Catering Ltd | Hospitality | 2025 |
| JRB Air Conditioning Limited | Energy | 2024 |
| JS FOX Estates Ltd | Real estate | 2016 |
| Juiced & Squeezed Limited | Hospitality | 2020 |
| Juju Trading Limited | Information & communication | 2014 |
| Jungle Training Limited | Professional & scientific | 2008 |
| Juno Assist Ltd | Transport & logistics | 2024 |
| Just Think Cleaning Ltd | Administrative & support | 2026 |
| Just Transition Limited | Professional & scientific | 2021 |
| Jutla Holdings Ltd | Real estate | 2024 |
| JZ Service Consulting Ltd | Other services | 2012 |
| K Romaniuk Limited | Construction | 2023 |
| K.W.Residents Management Limited | Real estate | 1965 |
| Kaizen Education Services Ltd | Education | 2025 |
| Kajo Hairsalon Limited | Other services | 2009 |
| Kang Business Limited | Construction | 2024 |
| Kartar's Kitchen Ltd | Manufacturing | 2023 |
| Kartar’S Classics Ltd | Wholesale & retail | 2024 |
| Kartfin Automation Limited | Information & communication | 2024 |
| Kasia Bigda Consultancy Limited | Professional & scientific | 2015 |
| Katie Zidie Properties Limited | Real estate | 2022 |
| Katy Stone Ltd | Manufacturing | 2023 |
| Kayleigh Knight Ltd | Other services | 2025 |
| KC and Partners Private Limited | Professional & scientific | 2024 |
| Kdcomputers Ltd | Information & communication | 2020 |
| Keada Sports Limited | Wholesale & retail | 2019 |
| Keay Roofing and Maintenance Services Limited | Construction | 2010 |
| KED S1 Limited | Health & social care | 2021 |
| Keen Accounts Ltd | Professional & scientific | 2010 |
| Kelso Training Ltd | Administrative & support | 2014 |
| Kelvin & Co Ltd | Wholesale & retail | 2012 |
| Kemetyl UK Ltd | Wholesale & retail | 2007 |
| Kendellco Ltd | Professional & scientific | 2022 |
| Kennel Green Management Limited | Households | 1993 |
| Kensington Park Limited | Real estate | 2016 |
| Keston-Bloom Ltd | Information & communication | 2023 |
| Kewbrook Limited | Real estate | 1982 |
| Khadra Management Ltd | Professional & scientific | 2023 |
| Kikko Capybara Ltd | Wholesale & retail | 2025 |
| Kimo Enterprises Limited | Wholesale & retail | 1986 |
| Kinetic Kitchen Ltd | Manufacturing | 2020 |
| King Financial Planning LLP | | 2019 |
| King's Yard Tenants' Association Limited | Households | 1975 |
| Kingfields Solicitors Limited | Professional & scientific | 2015 |
| Kingfisher Ponds Limited | Administrative & support | 2021 |
| Kingfisher Thistle Limited | Professional & scientific | 2023 |
| Kipster Media Limited | Professional & scientific | 2013 |
| Kirk Rice Audit LLP | | 2025 |
| Kirk Rice LLP | | 2010 |
| Kirkstone Conveyancing Ltd | Professional & scientific | 2025 |
| Kitelands Property Limited | Construction | 2017 |
| KJ Norfolk Developments Limited | Construction | 2012 |
| Kjec Ltd | Education | 2017 |
| Kmac Design Ltd | Professional & scientific | 2022 |
| KMM Consultancy Ltd | Real estate | 2023 |
| Knight Sports Therapy Limited | Health & social care | 2026 |
| Knightguard Shop Limited | Wholesale & retail | 2023 |
| Knowle Hill Properties Limited | Real estate | 2000 |
| Knss Ltd | Hospitality | 2011 |
| Komalware Consulting Limited | Information & communication | 2015 |
| Kotoi Ltd | Wholesale & retail | 2021 |
| Kreed Active Limited | Wholesale & retail | 2024 |
| Kushpoint Ltd | Information & communication | 2023 |
| KVA Virtual Assistance Ltd | Administrative & support | 2023 |
| Kymd Consulting Limited | Information & communication | 2013 |
| LA Carpentry London Limited | Professional & scientific | 2021 |
| LA Carpentry Southern Limited | Construction | 2021 |
| LA Sorrentina Ltd | Hospitality | 2025 |
| Labour Business Limited | Administrative & support | 2012 |
| Lagom Living Ltd | Real estate | 2020 |
| Lagom One Limited | Real estate | 2025 |
| Lahoz Ltd | Professional & scientific | 2016 |
| Laine-Liryc Consulting Ltd | Information & communication | 2017 |
| Laizie Ltd | Other services | 2022 |
| Lakeview 1964 Limited | Extraterritorial | 2014 |
| Lakeview Management Company (Ascot) Limited | Households | 1987 |
| Lakeview Monkey Sanctuary Ltd | Arts & recreation | 2007 |
| Lamebrain OWL Ltd | Wholesale & retail | 2021 |
| Land & Renewable Investments Ltd | Real estate | 2023 |
| Landmark Legacy Estates Ltd | Construction | 2025 |
| Langdale Logistics Ltd | Information & communication | 2022 |
| Langham Home Developments Limited | Administrative & support | 2019 |
| Langham Scott Limited | Real estate | 2007 |
| Langley Management Company Limited | Households | 2004 |
| Lansdowne Aviation Consulting Ltd | Education | 2019 |
| Laserglobe (Investments) Limited | Real estate | 2003 |
| Latigo Energy Limited | Professional & scientific | 2016 |
| Lauren Neville Art Limited | Arts & recreation | 2023 |
| Lavender Park Limited | Professional & scientific | 2010 |
| Lawless Film Lighting Ltd | Construction | 2025 |
| Lawrence Legacy Portfolio Ltd | Real estate | 2022 |
| LC Scenery Ltd | Manufacturing | 2021 |
| LDB Planning Limited | Professional & scientific | 2010 |