| Kuki Monster Entertainment Limited | Information & communication | 2014 |
| Kuki Monster Holdings Limited | Financial services | 2022 |
| Kult Ltd | Information & communication | 2012 |
| Kumar Technologies Ltd | Information & communication | 2012 |
| Kumari Transport Ltd | Administrative & support | 2017 |
| Kutech Solutions Limited | Extraterritorial | 2021 |
| Kvasir Research Ltd | Professional & scientific | 2018 |
| KW Social Limited | Professional & scientific | 2024 |
| KW71 Limited | Professional & scientific | 2024 |
| Kwasont Productions Ltd | Information & communication | 2023 |
| KWH (UK) Ltd | Financial services | 2011 |
| Kwzl Investments Limited | Financial services | 2012 |
| Kyro (Sussex) Limited | Health & social care | 2014 |
| L & C Theatres Limited | Arts & recreation | 1988 |
| L & J Holdings (Southern) Ltd | Real estate | 2023 |
| L & M Rigby LLP | | 2012 |
| L & S Office Supplies Limited | Wholesale & retail | 2006 |
| L & S Printing Company Limited | Manufacturing | 1981 |
| L 'N Roses Limited | Other services | 2018 |
| L and F Electrical Services Limited | Manufacturing | 1995 |
| L and J Sealants Ltd | Construction | 2026 |
| L D Property Building and Construction Limited | Construction | 2026 |
| L D Property Services and Maintenance Limited | Construction | 2025 |
| L Guess Jewellers Limited | Wholesale & retail | 2010 |
| L J Barling Limited | Real estate | 2014 |
| L Neller Electrical Services Ltd | Construction | 2011 |
| L R Nominees Limited | Administrative & support | 1999 |
| L&A Race Support Limited | Wholesale & retail | 2019 |
| L&L Fulfilment Limited | Wholesale & retail | 2024 |
| L&V Electrical Limited | Construction | 2021 |
| L. Anderson (Haywards Heath) Limited | Other services | 2006 |
| L. Gardens Management Company Limited | Households | 2026 |
| L.A.M. Audio Visual Ltd | Administrative & support | 2025 |
| L.D.S. Leak Detection Specialists Ltd | Administrative & support | 2010 |
| L.E.S. Consulting Limited | Administrative & support | 2010 |
| L.I.Am (Sussex) Limited | Financial services | 2022 |
| L3WG Holdings Limited | Financial services | 2025 |
| L3WG Limited | Information & communication | 2025 |
| L3WG Properties Limited | Real estate | 2025 |
| LA Belle at Home Ltd | Other services | 2021 |
| LA Campania by the Sea Limited | Hospitality | 2018 |
| LA Hair and Beauty Limited | Other services | 2025 |
| LA Studio Worthing Limited | Other services | 2017 |
| Laal Delivery Ltd | Transport & logistics | 2025 |
| Label-Link Limited | Manufacturing | 2016 |
| Lacuna Coaching Ltd | Administrative & support | 2018 |
| Laddoo Ltd | Wholesale & retail | 2025 |
| Ladj Ltd | Real estate | 2019 |
| Lady DEE Limited | Health & social care | 2022 |
| Lady Luck Studio Ltd | Other services | 2023 |
| Lahc Ltd | Professional & scientific | 2016 |
| Laila Cosmetics Limited | Professional & scientific | 2022 |
| Laine Ltd | Arts & recreation | 2009 |
| Lake Investments Limited | Construction | 1999 |
| Lamb Electrical Ltd | Construction | 2019 |
| Lambhof Limited | Administrative & support | 2017 |
| Lambourne and Moulding Ltd | Wholesale & retail | 2021 |
| Lambourne and Moulding Property Ltd | Real estate | 2025 |
| Lamorna Holdings Ltd | Financial services | 2022 |
| Lancashire Repetition Limited | Professional & scientific | 1960 |
| Lancing Dental Care Limited | Health & social care | 2013 |
| Lancing Glass Works Limited | Construction | 1972 |
| Land & Brand New Homes Limited | Real estate | 2002 |
| Land and Associates Surveying Limited | Professional & scientific | 2026 |
| Land Business Strategist Limited | Other services | 2019 |
| Landfall (2007) Limited | Real estate | 2007 |
| Landmore Financial Services Ltd | Financial services | 2006 |
| Landmore Property Services Limited | Financial services | 2015 |
| Laney 103 Ltd | Information & communication | 2023 |
| Lanfranc Park Property Management Ltd | Real estate | 2017 |
| Langbourne Management Limited | Administrative & support | 2009 |
| Langbourne Services Limited | Real estate | 2005 |
| Langham Groundworks Limited | Construction | 2013 |
| Langhorn Investments Limited | Professional & scientific | 2006 |
| Langley Lifestyle Services Limited | Households | 2003 |
| Langnell Limited | Professional & scientific | 2014 |
| Langstone Cost Management Limited | Professional & scientific | 2013 |
| Lansdowne Nursery Plants Limited | Agriculture & fishing | 2013 |
| Larch Landscape Consultancy and Design Ltd | Professional & scientific | 2021 |
| Lark Wines Ltd | Hospitality | 2024 |
| Laroma Therapies Limited | Health & social care | 2015 |
| Latchgate Services Ltd | Professional & scientific | 2023 |
| Latin Multi Services Limited | Information & communication | 2020 |
| Latitude Creative Limited | Professional & scientific | 2021 |
| Lattegelato Cakes & Coffee Ltd | Manufacturing | 2023 |
| Laugh and Learn Tarring Limited | Education | 2017 |
| Laundry Lane Productions Ltd | Information & communication | 2025 |
| Laura Daniels Physiotherapy Ltd | Health & social care | 2014 |
| Laura Harrison Occupational Psychology Ltd | Professional & scientific | 2025 |
| Laura House Developments Ltd | Construction | 2024 |
| Laura M W Co Limited | Construction | 2025 |
| Lauren Michelle Pires Ltd | Other services | 2025 |
| Laurie Rose Ltd | Information & communication | 2006 |
| Laurie Rowan Ltd | Information & communication | 2015 |
| Lava 24 Ltd | Construction | 2026 |
| Lavella Group Limited | Financial services | 2022 |
| Lavella Limited | Financial services | 2021 |
| Lavinia Organisations Ltd | Other services | 2020 |
| Law Street Recruitment Limited | Administrative & support | 2021 |
| Lawford Knight Limited | Administrative & support | 2014 |