| JCM Media Limited | Information & communication | 2024 |
| Jddw Consultancy Limited | Professional & scientific | 2023 |
| JDS Prosper Property Limited | Real estate | 2025 |
| JEC Dallas Wholesale & Distribution Ltd | Wholesale & retail | 2021 |
| Jeewizz Limited | Wholesale & retail | 2013 |
| Jingshun Ltd | Hospitality | 2025 |
| JJH Site Management Limited | Construction | 2016 |
| JO Desire Homes Ltd | Wholesale & retail | 2023 |
| Joalna Limited | Other services | 2023 |
| JOE Steggles Consulting Ltd | Professional & scientific | 2026 |
| John KAY Maritime Limited | Manufacturing | 2026 |
| John Kidly Ltd | Arts & recreation | 2024 |
| JPM Scenery Holdings Ltd | Financial services | 2024 |
| JPM Scenery Ltd | Manufacturing | 2020 |
| JS Shipping Ltd | Transport & logistics | 2020 |
| JT FX Ltd | Construction | 2022 |
| Juliana Baite Ltd | Health & social care | 2022 |
| Junik Limited | Hospitality | 2006 |
| Juniper Gardens (Sunbury) Limited | Households | 1992 |
| JWC Evolve Limited | Professional & scientific | 2024 |
| JWJ Projects Ltd | Administrative & support | 2012 |
| K Brown Carpet Fitting Ltd | Construction | 2002 |
| K&S Beauty Ltd | Other services | 2019 |
| K.B. Come Clean Ltd | Administrative & support | 2007 |
| K.V. Scaffolding Ltd | Construction | 2008 |
| KAE Travel Limited | Administrative & support | 2023 |
| Kags Consultants Ltd | Professional & scientific | 2023 |
| Kahuna Spirits Ltd | Wholesale & retail | 2021 |
| KAM Consulting Group Limited | Transport & logistics | 2026 |
| Kate Thompson Media Ltd | Arts & recreation | 2015 |
| Katie Ella Perry Interiors Ltd | Professional & scientific | 2023 |
| Kaya Group Investments Ltd | Other services | 2019 |
| Kaybury Properties Limited | Real estate | 2007 |
| Kchoi Consulting Limited | Information & communication | 2015 |
| Ke-Bears Care Limited | Health & social care | 2020 |
| Keeks Clinic Ltd | Other services | 2024 |
| Keeping the Dream Alive Ltd | Hospitality | 2024 |
| Keicar Solutions Limited | Professional & scientific | 2018 |
| Kelican Construction Ltd | Manufacturing | 2025 |
| Kevin Theobald Recruitment Ltd | Administrative & support | 2012 |
| KFS Resourcing Ltd | Construction | 2015 |
| Kiddi Karts Limited | Arts & recreation | 1998 |
| Kims Laser CUT Keys Limited | Wholesale & retail | 2007 |
| Kineticore Pilates Limited | Arts & recreation | 2024 |
| Kingsley Court Management (Worcester Park) Limited | Households | 2012 |
| Kingston Physio Limited | Health & social care | 2005 |
| Kingswood Close Residents Company Ltd | Households | 2013 |
| Kinly Bidco Limited | Financial services | 2020 |
| KKJ Consultants Ltd | Construction | 2023 |
| KM Honey Limited | Agriculture & fishing | 2024 |
| KML Consultants Ltd | Professional & scientific | 2023 |
| KN Software Solutions Limited | Information & communication | 2023 |
| Komina Ragihandina Ciwanan Ltd | Professional & scientific | 2026 |
| Kontrol Freax Limited | Administrative & support | 2003 |
| KP Build Contractors Ltd | Construction | 2024 |
| Kraan Limited | Administrative & support | 2025 |
| Krish Harman Cars Ltd | Wholesale & retail | 2015 |
| KS Consulting Services Limited | Information & communication | 2007 |
| KSM Installations Limited | Construction | 2011 |
| KTK Build Solutions Ltd | Construction | 2015 |
| Kudos First Limited | Wholesale & retail | 2009 |
| Kudos Mobility Group Limited | Health & social care | 2014 |
| Kudos Mobility Services Limited | Households | 2014 |
| Kudos Stairlifts Limited | Other services | 2014 |
| Kumar Platinum Homes Ltd | Real estate | 2023 |
| Kurly Entertainment Ltd | Information & communication | 2015 |
| KVL Plumbing Ltd | Construction | 2011 |
| L & a Future Ltd | Administrative & support | 2023 |
| L.I Roofing Ltd | Construction | 2018 |
| LA Belle Hair Salon Ltd | Other services | 2013 |
| LA Molienda Ltd | Wholesale & retail | 2024 |
| Lady Estates Ltd | Transport & logistics | 2017 |
| Laffoy Construction Limited | Construction | 2010 |
| Landmarked Property Ltd | Real estate | 2023 |
| Lark Avenue Residents Association Limited | Households | 1973 |
| Latam Invest Limited | Wholesale & retail | 2025 |
| Latka Construction Ltd | Construction | 2018 |
| Lauderdale House RTM Company Limited | Households | 2009 |
| Laura Townsend Ltd | Professional & scientific | 2018 |
| Lavender Gardens Residents Limited | Households | 2010 |
| Layered Walls UK Ltd | Real estate | 2022 |
| LDD Consulting Ltd | Professional & scientific | 2010 |
| Leolibra Ltd | Professional & scientific | 2024 |
| Leos Poke Vault Ltd | Wholesale & retail | 2024 |
| Letterbox Candy Limited | Wholesale & retail | 2021 |
| Lewin Heating & Plumbing Services Limited | Construction | 1999 |
| Lexbolt AI Ltd | Information & communication | 2025 |
| LHR Transport Services Ltd | Transport & logistics | 2025 |
| Libra Mortgages Limited | Financial services | 2025 |
| Lifecycle Advantage Consulting Ltd | Professional & scientific | 2025 |
| Lifted Media Ltd | Professional & scientific | 2025 |
| Link Invest Limited | Real estate | 2024 |
| Lionel Consultancy Ltd | Information & communication | 2022 |
| Livelee Skips Limited | Construction | 2017 |
| LKH Advisors Ltd | Professional & scientific | 2016 |
| Llandod Properties Ltd | Real estate | 2025 |
| LMS Power & Lighting Ltd | Construction | 2021 |
| Locked in Education C.I.C. | Education | 2025 |
| Logicair Services Limited | Construction | 2026 |
| London Academy of Medical Aesthetics Ltd | Education | 2025 |