| Lewess Hand Car Wash Ltd | Other services | 2018 |
| LFO Sound Limited | Information & communication | 2013 |
| LFT Investments | Financial services | 2022 |
| LG TV Ltd | Information & communication | 2012 |
| Lgbtq+ Dementia Advisory Group Community Interest Company | Information & communication | 2023 |
| Liaison Gallery Ltd | Wholesale & retail | 2024 |
| Libertalia Brewing Company Limited | Manufacturing | 2023 |
| Libra Property Ventures Ltd | Real estate | 2021 |
| Light Farm Sussex Limited | Hospitality | 2022 |
| Light Foot Energy Ltd | Wholesale & retail | 2018 |
| Lightbulb Insight Limited | Arts & recreation | 2020 |
| Lilac Ideas Ltd | Professional & scientific | 2023 |
| Lime Tree Consulting Limited | Professional & scientific | 2020 |
| Limewood (Reigate) Residents Management Limited | Households | 2025 |
| LIN Peters Limited | Health & social care | 2003 |
| Lindsay Barchan Ltd | Professional & scientific | 2019 |
| Linklawns Property Management Limited | Households | 1991 |
| Linsted Investments Limited | Real estate | 2017 |
| Liquid Studio Limited | Professional & scientific | 2008 |
| Liros Ropes UK Limited | Wholesale & retail | 2003 |
| Lisa Emery Limited | Information & communication | 2024 |
| Little Acorn Eco Ltd | Construction | 2019 |
| Little Cleaver Barns Ltd | Construction | 2025 |
| Little Dene Services Limited | Other services | 2021 |
| Little Seed Design Ltd | Other services | 2011 |
| Little Sussex Limited | Information & communication | 2022 |
| Littlestone Properties (Bedhampton) Limited | Real estate | 1964 |
| Living Well Dying Well Ltd | Information & communication | 2016 |
| LIZ Poole Limited | Arts & recreation | 2012 |
| LJA Assets Ltd | Construction | 2025 |
| LM Versatile Ltd | Construction | 2026 |
| LMK Nails & Spa Ltd | Other services | 2024 |
| Load'Er Entertainment Ltd | Wholesale & retail | 2024 |
| Lodge Lane Management Company Limited | Households | 1997 |
| Logistic Supply Solutions Ltd | Transport & logistics | 2012 |
| Lolli&Mimi Ltd | Wholesale & retail | 2020 |
| London Azimuth Ltd | Professional & scientific | 2023 |
| Longbridge (Sussex) Limited | Agriculture & fishing | 2021 |
| Longhalves Stud Ltd | Agriculture & fishing | 2022 |
| Longmont LLC | | 2023 |
| Look UP Limited | Professional & scientific | 2023 |
| Loopmasters Limited | Information & communication | 2009 |
| Lost Dog Dance Limited | Arts & recreation | 2013 |
| Loud Productions Ltd | Information & communication | 2003 |
| Louise Winters Consulting Limited | Information & communication | 2015 |
| Loulux Abodes LLP | | 2024 |
| Love Baby Swim School Ltd | Arts & recreation | 2013 |
| Love OUR Ouse CIC | Other services | 2022 |
| Lovebrook CIC | Agriculture & fishing | 2022 |
| Lowmass Wheels Limited | Wholesale & retail | 2025 |
| LSR Fineview Ltd | Real estate | 2022 |
| Lsub CIC | Other services | 2020 |
| LT Accounts Ltd | Professional & scientific | 2026 |
| Luberon Provence Ltd | Administrative & support | 2020 |
| Lucas & Paul Limited | Administrative & support | 2020 |
| Lucky Beau Ltd | Wholesale & retail | 2023 |
| Lude Investments Limited | Real estate | 2022 |
| Lumi Solar Solutions Ltd | Construction | 2024 |
| Luminary Studio Limited | Real estate | 2022 |
| Luminary Trend Consultancy Limited | Professional & scientific | 2012 |
| Luna Rehab Limited | Public administration | 2019 |
| Lusco Ltd | Wholesale & retail | 2021 |
| LUX Heating & Bathrooms Limited | Construction | 2021 |
| Lwdw Training Limited | Education | 2015 |
| Lyons Finance Limited | Other services | 2011 |
| Lyons Finance Property Ltd | Real estate | 2020 |
| Lyra's Cottages Ltd | Real estate | 2024 |
| LYS DE Temps Ltd | Administrative & support | 2026 |
| LYT Productions CIC | Education | 2023 |
| M & W Associates (Agencies) Limited | Administrative & support | 2010 |
| M Dawson Consulting Ltd | Professional & scientific | 2021 |
| Macdonald Associates Consultancy Limited | Professional & scientific | 2003 |
| Machina Silvam Ltd | Financial services | 2021 |
| Mackellar Schwerdt LLP | | 2017 |
| Mackenzie Philips Limited | Administrative & support | 2006 |
| Made by Brave Foundation Limited | Health & social care | 2026 |
| Made by Brave Limited | Manufacturing | 2017 |
| Maggies of Lewes Ltd | Wholesale & retail | 2026 |
| Magic Lantern Productions Limited | Information & communication | 1996 |
| Magnetic Storm Limited | Information & communication | 1997 |
| Magpie Strategy Ltd | Professional & scientific | 2025 |
| Mahler Property Limited | Real estate | 2015 |
| Mailma Limited | Information & communication | 2024 |
| MAJ Performance Tuning Limited | Wholesale & retail | 2016 |
| Maltonite Nexus Ltd | Information & communication | 2024 |
| MAN Academy Ltd. | Education | 2022 |
| MAN of Many Words Limited | Other services | 2010 |
| Maniac Squat Ltd | Arts & recreation | 2004 |
| Mansell Mctaggart Lewes Limited | Real estate | 2023 |
| Marcusmum Limited | Professional & scientific | 2024 |
| Marenka Limited | Hospitality | 2010 |
| Margot House Ltd | Wholesale & retail | 2026 |
| Mari 21 Real Estate Ltd | Households | 2012 |
| Mark Lawson Bell Limited | Arts & recreation | 2008 |
| Mark Moody Limited | Information & communication | 2013 |
| Mark&Edds Tree Surgery & Landscape Gardening Ltd | Administrative & support | 2024 |
| Marketing Hero Ltd | Administrative & support | 2023 |
| Marketing Success 4 U Limited | Professional & scientific | 2010 |
| Marks Meals Weddings and Events Ltd | Hospitality | 2024 |
| Marlea GBS Ltd | Construction | 2018 |