| Jamie Southgate Coaching Services Limited | Arts & recreation | 2014 |
| Jaromi Ltd | Transport & logistics | 2025 |
| JB Travel & Touring Ltd | Administrative & support | 2023 |
| Jdmtransportservices Ltd | Transport & logistics | 2023 |
| Jennings Wilson Associates Limited | Professional & scientific | 2015 |
| Jeyh Developments Limited | Construction | 2022 |
| JJ Cars Weybridge (Home to School Run) Ltd | Transport & logistics | 2026 |
| JJ Cars Weybridge Ltd | Transport & logistics | 2025 |
| JL Engineering London Limited | Wholesale & retail | 2010 |
| JM Build Ltd | Construction | 2009 |
| JM Coffee Limited | Hospitality | 2021 |
| JMG Build Ltd | Construction | 2015 |
| JO Robbens Photography Limited | Professional & scientific | 2026 |
| JRE Estates Ltd | Real estate | 2022 |
| Jtjageel Limited | Professional & scientific | 2025 |
| Juniper Court RTM Company Limited | Households | 2021 |
| Just Extend Your Home Ltd | Construction | 2014 |
| Just Extend Your House Ltd | Construction | 2011 |
| K Hourigan Electrics Ltd | Construction | 2010 |
| K L Perrin Limited | Information & communication | 2022 |
| K9 HQ Limited | Other services | 2015 |
| Kandr Carwash Ltd | Other services | 2025 |
| Karzmic Ltd | Information & communication | 2011 |
| Kate Escapes Ltd | Administrative & support | 2026 |
| KD International Corporation Limited | Wholesale & retail | 2017 |
| KDR Innovations Ltd | Construction | 2026 |
| Keeble Holdings Limited | Professional & scientific | 1998 |
| Kerry Loughran Creative Ltd | Arts & recreation | 2015 |
| Keshav Packaging Solutions Ltd | Administrative & support | 2026 |
| Key to Success Ltd. | Education | 2008 |
| Kings Window Cleaning Limited | Administrative & support | 2018 |
| Kiwiana Limited | Administrative & support | 2002 |
| Knightquest Ltd | Information & communication | 2016 |
| Knights Asbestos Ltd | Water & waste | 2025 |
| Knights Close (Molesey) Residents Management Company Limited | Households | 2005 |
| Kodiak Media Limited | Information & communication | 2025 |
| Kokeb - Accountancy & Bookkeeping Ltd | Professional & scientific | 2019 |
| Kordeus Ltd | Information & communication | 2026 |
| Koyar Carpentry Ltd | Construction | 2019 |
| KSJ Capital Ltd | Financial services | 2025 |
| Lacd UK Limited | Professional & scientific | 1988 |
| Lamego Hounslow Ltd | Hospitality | 2022 |
| Landgenics Ltd | Extraterritorial | 2025 |
| Landscaping Solutions Limited | Construction | 2005 |
| Laniakea Creative Ltd | Arts & recreation | 2018 |
| LAU Design Studio Limited | Professional & scientific | 2023 |
| Lavender Hill Advisory Limited | Real estate | 2021 |
| Lavender Hill ADVISORY1 Limited | Professional & scientific | 2021 |
| LBS Building Services Ltd | Administrative & support | 2018 |
| Lclh Properties Limited | Real estate | 2025 |
| Lebanese Box Ltd | Hospitality | 2024 |
| Leoluna Logistics Ltd | Transport & logistics | 2019 |
| Leondore Property Developments Limited | Real estate | 1971 |
| Lesta Professionals Ltd | Administrative & support | 2019 |
| Letzpocket Ltd | Real estate | 2025 |
| Linden Lodge Ltd | Health & social care | 2024 |
| Linden Lodge Property Ltd | Real estate | 2024 |
| Lite Yoga CIC | Agriculture & fishing | 2026 |
| Little Oaks House Ltd | Health & social care | 2025 |
| Little Oaks House Property Ltd | Real estate | 2025 |
| Living Concrete Ltd | Manufacturing | 2016 |
| LK Tree and Garden Care Ltd | Administrative & support | 2022 |
| LME Media Limited | Information & communication | 2023 |
| Lockrowber Hospitality Limited | Hospitality | 2024 |
| Loft and Extension Conversion Specialist Ltd | Construction | 2023 |
| London Baby Swimming LLP | | 2015 |
| London Bakeries Ltd | Hospitality | 2026 |
| London Superstores Ltd | Wholesale & retail | 2024 |
| Longley Properties Limited | Health & social care | 2009 |
| Lorac Lodge Ltd | Health & social care | 2020 |
| Lorac Property Ltd | Households | 2020 |
| LR Disco Entertainment Ltd | Arts & recreation | 2017 |
| Lucas Risk Management Ltd | Financial services | 2022 |
| Ludwell Ltd | Professional & scientific | 2025 |
| Luke Ritchie Ltd | Information & communication | 2023 |
| M & Boiko's Ltd | Administrative & support | 2012 |
| M B Property Solutions Limited | Real estate | 2012 |
| Macai - Limited | Construction | 1989 |
| Macai Group Limited | Financial services | 2016 |
| Macai Projects Limited | Construction | 2010 |
| Macscheen Services Ltd | Administrative & support | 2022 |
| Made for Documentary LLP | | 2022 |
| Magnat-Kitchens Ltd | Construction | 2006 |
| Mahirah Corporation Ltd | Wholesale & retail | 2024 |
| Maker Film Co Ltd | Information & communication | 2024 |
| Mamzenko Ltd | Professional & scientific | 2015 |
| Markah Ltd | Professional & scientific | 2019 |
| Marlborough Lodge Management Limited | Health & social care | 2007 |
| Martins Boat Hire Ltd | Administrative & support | 2025 |
| Maxwell Crooks Limited | Arts & recreation | 2013 |
| Maya Home Cleaning Limited | Administrative & support | 2024 |
| MB Bathrooms Ltd | Construction | 2026 |
| MB Property Solutions (Dunstable) Ltd | Real estate | 2024 |
| MC Supermarket Limited | Hospitality | 2025 |
| Mckenzie Brown Developments Limited | Real estate | 2020 |
| MCX Systems Ltd | Construction | 2026 |
| Meadow Farm WH Limited | Agriculture & fishing | 2015 |
| Medflow Scaling Ltd | Professional & scientific | 2025 |
| Media Marmot Ltd | Information & communication | 2011 |
| Mega Motors Ltd | Wholesale & retail | 2022 |