| L F and Sons Ltd | Construction | 2025 |
| L'Oiseau Limited | Professional & scientific | 1998 |
| L-Pace Sentinel Systems Ltd | Public administration | 2026 |
| LAB Consultancy Solutions Limited | Professional & scientific | 2021 |
| Lacey's Baby Co. Ltd | Wholesale & retail | 2008 |
| Laiya Ltd | Hospitality | 2022 |
| LAN Advisory Services LLP | | 2009 |
| Landalls Limited | Hospitality | 1947 |
| Langley's Mechanics Ltd | Wholesale & retail | 2026 |
| Langley's Mots Ltd | Wholesale & retail | 2026 |
| Langley’S Garage Ltd | Wholesale & retail | 2020 |
| Lansdowne-Holland RTM Company Limited | Households | 2018 |
| Larkin Rail Group Ltd | Construction | 2026 |
| Larkmyle Consultancy Limited | Health & social care | 2022 |
| Larkmyle Ltd | Health & social care | 2014 |
| Laser Vine Ltd | Manufacturing | 2012 |
| Laundry Ninjas Ltd | Administrative & support | 2015 |
| Laura LEE Jewellery Limited | Manufacturing | 2003 |
| Laura Smythe PR Ltd | Professional & scientific | 2015 |
| Lauren Hurst Ltd | Professional & scientific | 2014 |
| Lawn Court Bexhill Limited | Real estate | 2018 |
| Lawton & Dawe Properties Limited | Households | 2010 |
| Lazzdir Limited | Hospitality | 2019 |
| Lean Simulator Ltd | Education | 2025 |
| Leaping Frog Solutions Ltd | Professional & scientific | 2025 |
| Learning for Success Limited | Professional & scientific | 2001 |
| Leaves Limited | Health & social care | 2013 |
| LEE Charles Designs Ltd | Wholesale & retail | 2025 |
| Legacy Rail Ltd | Professional & scientific | 2019 |
| LEO Sharma Medical Limited | Health & social care | 2017 |
| Leroy Impex UK Ltd | Wholesale & retail | 2025 |
| Leslie Developments Limited | Construction | 1996 |
| Letterboxkits Limited | Wholesale & retail | 2014 |
| Lettings Homes (UK) Limited | Real estate | 2016 |
| Lewis Pownall Ltd | Real estate | 2014 |
| LG Optical (MFG) Limited | Manufacturing | 1999 |
| Liberatingtouch Centre Limited | Information & communication | 2013 |
| Lifa (UK) Limited | Financial services | 2013 |
| Lifetime Cars Ltd | Wholesale & retail | 2023 |
| Light Space Color Ltd | Professional & scientific | 2020 |
| LIGHT42DANKO Ltd | Information & communication | 2025 |
| Lighthouse Portfolio Investments Ltd | Real estate | 2026 |
| Limitless Autos Ltd | Wholesale & retail | 2023 |
| Limitless Welding and Fabrication Ltd | Construction | 2020 |
| Linstead RTM Company Limited | Households | 2021 |
| Lior Wellness Studio Ltd | Other services | 2024 |
| Little Mashers Limited | Wholesale & retail | 2010 |
| Little Star Software Ltd | Information & communication | 2010 |
| Living Word (Hailsham) | Other services | 2001 |
| LJB Automotive A/C Solutions Ltd | Professional & scientific | 2026 |
| LJM Global Logistics Ltd | Transport & logistics | 2026 |
| LO Consulting Limited | Professional & scientific | 2005 |
| LOG Cabins LV Ltd | Construction | 2013 |
| Logotouch Ltd | Professional & scientific | 2015 |
| Loiter Ltd | Wholesale & retail | 2026 |
| London Wharf Property Management Company Ltd | Real estate | 2013 |
| Longwood (Eastbourne) Management Company Limited | Hospitality | 1995 |
| Lost for Words (UK) Limited | Information & communication | 2013 |
| Love Digital Consultancy Ltd | Extraterritorial | 2017 |
| Love Drums Ltd | Wholesale & retail | 2014 |
| Lovell Landscapes Ltd | Administrative & support | 2016 |
| Lucas Vega Medical Ltd | Transport & logistics | 2015 |
| Ludlow Architects Ltd | Professional & scientific | 2021 |
| Lumigroup Sussex Limited | Construction | 2026 |
| Luna Organisation Limited | Wholesale & retail | 2021 |
| Lund's Pharma Ltd | Wholesale & retail | 2023 |
| Luxecraft Studios Ltd | Wholesale & retail | 2025 |
| Luxury Home Maintenance and Repairs Services Limited | Construction | 2018 |
| LWT Health Care Limited | Health & social care | 2018 |
| Lynton Court (Hove) Limited | Households | 2003 |
| M S T Partnership LLP | | 2004 |
| M&M Property Traders Limited | Construction | 2025 |
| M&W Property Sales Ltd | Real estate | 2014 |
| MA Pay's Products Limited | Hospitality | 2018 |
| Macaw Homes Ltd | Real estate | 2022 |
| Macelec Limited | Construction | 2012 |
| Magic WOK Brother Limited | Hospitality | 2024 |
| Makers' House Hastings Ltd | Education | 2025 |
| Malard Investments Limited | Real estate | 2016 |
| Mamamda Car Wash Limited | Administrative & support | 2024 |
| Manor Building (S E) Ltd | Construction | 2025 |
| Mapleridge Ltd | Construction | 2025 |
| Marina Retail Store Limited | Wholesale & retail | 2024 |
| Marine Court (ST Leonards on Sea) Freeholders Limited | Real estate | 2005 |
| Marine Seaside Ltd | Real estate | 2024 |
| Mark Goodman Limited | Construction | 2014 |
| Marrs Limited | Professional & scientific | 2003 |
| Marshal 19 Ltd | Transport & logistics | 2019 |
| Marshall-Tufflex Energy Management Limited | Wholesale & retail | 1991 |
| Marshall-Tufflex International Limited | Wholesale & retail | 1951 |
| Marshall-Tufflex Limited | Manufacturing | 1942 |
| Martial Arts Hastings Limited | Arts & recreation | 2018 |
| Marton Lettings Ltd | Real estate | 2020 |
| Mary Valentine Wildcrafted Skincare Ltd | Manufacturing | 2022 |
| Match and Dispatch Ltd | Administrative & support | 2024 |
| Maticians Ltd | Arts & recreation | 2019 |
| Matsushi Limited | Real estate | 2017 |
| Mayfly Analytics Ltd | Information & communication | 2021 |
| MBH & JLH Decorators Limited | Administrative & support | 2016 |
| MBS Risk Advisory Ltd | Professional & scientific | 2024 |