| Lecusse Coastal UK Ltd | Real estate | 2025 |
| Leds 4 ME Limited | Wholesale & retail | 2010 |
| LEE Design Limited | Construction | 2003 |
| LEE Jones Heating Limited | Construction | 2021 |
| LEE Jones Kitchens & Bathroom Services Ltd | Construction | 2025 |
| LEE Lettings Limited | Real estate | 2026 |
| LEE Richards Printworks Limited | Manufacturing | 2022 |
| Leeder Estates Limited | Real estate | 2021 |
| Leeder Property Consultants Limited | Households | 2011 |
| Leeder Property Management Ltd | Real estate | 2024 |
| Leena Food and Wine Limited | Wholesale & retail | 2022 |
| Leeward Securities Limited | Real estate | 1963 |
| Legacy Protection Planning Limited | Financial services | 2023 |
| Legacy Roofing South Wales Ltd | Construction | 2023 |
| Legacy VR Limited | Arts & recreation | 2023 |
| Legal Services Consultancy Ltd | Professional & scientific | 2021 |
| Lehane Autos Limited | Wholesale & retail | 2019 |
| Leigh Harris Limited | Mining & quarrying | 2017 |
| Leighton Rees & Co Ltd | Other services | 2019 |
| Leisure Active Training Ltd. | Education | 2016 |
| Leisure Guys Limited | Wholesale & retail | 2018 |
| Leisure Holiday Parks Limited | Hospitality | 2019 |
| LEJ Holdings Limited | Professional & scientific | 2023 |
| LEJ Housing Group Limited | Real estate | 2026 |
| LEJ Housing Solutions Ltd | Real estate | 2026 |
| Lemonade Hair Swansea Ltd | Other services | 2022 |
| Lemongrass Limited | Information & communication | 2025 |
| Lemontree C L Ltd | Professional & scientific | 2026 |
| Lenhest Motors Limited | Wholesale & retail | 1990 |
| Lennios Fish Bar @ Hendy Ltd | Hospitality | 2024 |
| LEO Ro-Trans Ltd | Transport & logistics | 2024 |
| Leon Wright Limited | Manufacturing | 2026 |
| Leonardo's Guest House Limited | Hospitality | 2021 |
| LEP Brokerage Services Ltd | Wholesale & retail | 2025 |
| Lepar Ltd | Professional & scientific | 2025 |
| Leridian Technical Services Ltd | Professional & scientific | 2016 |
| Lerwell Locum Ltd | Wholesale & retail | 2021 |
| Leslie Enterprises Limited | Hospitality | 2019 |
| Less IS More Candy Limited | Wholesale & retail | 2025 |
| LET US Furnish Limited | Administrative & support | 2010 |
| Let's Connect Electrical Services Ltd | Construction | 2023 |
| Let's Go Travel (Wales) Limited | Transport & logistics | 2002 |
| Letha Consultancy Limited | Professional & scientific | 2006 |
| Lethcorp Limited | Wholesale & retail | 2005 |
| Letting Solutions Swansea Ltd | Real estate | 2019 |
| Letting Stars Properties Ltd | Real estate | 2022 |
| Letzee 360 Virtual Tours Ltd | Information & communication | 2023 |
| Leucarum Consultancy Services Limited | Professional & scientific | 2021 |
| Leucarum Properties Limited | Real estate | 2017 |
| Leucarum Property Development Limited | Real estate | 2017 |
| LEV Transport & Logistics Limited | Wholesale & retail | 2022 |
| Lev-X Property Limited | Real estate | 2026 |
| Levant Delights UK Limited | Manufacturing | 2017 |
| Level UP Edumarketing Ltd | Wholesale & retail | 2026 |
| Level UP Play Ltd | Arts & recreation | 2026 |
| LEVEL256 Ltd | Hospitality | 2023 |
| Lewis & Ingham Tennis Services Limited | Education | 2026 |
| Lewis Bros (Broadway Garage) Limited | Wholesale & retail | 2004 |
| Lewis Burden Ltd | Professional & scientific | 2025 |
| Lewis Chemist Limited | Health & social care | 2004 |
| Lewis Data Management Ltd | Information & communication | 2023 |
| Lewis Digital Services Ltd | Information & communication | 2024 |
| Lewis Hullin Associates Ltd | Financial services | 2019 |
| Lewis Hullin Group Ltd | Financial services | 2024 |
| Lewis Industrial Design Solutions Ltd | Professional & scientific | 2021 |
| Lewis Jolly Ltd | Health & social care | 2026 |
| Lewis Pies Holdings Limited | Professional & scientific | 2016 |
| Lewis Sundas Medical Limited | Health & social care | 2019 |
| Lewis Tarmac Ltd | Construction | 2026 |
| Lewis Thomas Limited | Information & communication | 2013 |
| Lexigo Ltd | Professional & scientific | 2014 |
| Lexi’S Treats Ltd | Wholesale & retail | 2025 |
| Lexmark Ltd | Real estate | 2024 |
| Lexrosa Ltd | Professional & scientific | 2023 |
| LFG Transport Services Limited | Transport & logistics | 2021 |
| LFN Building and Home Improvements Limited | Construction | 2014 |
| LG Agent Services Limited | Administrative & support | 2014 |
| LG Brickwork Services Ltd | Construction | 2026 |
| LG Management Services Limited | Professional & scientific | 2024 |
| Lgoknowledge Limited | Information & communication | 2008 |
| LH Brook Protect Limited | Financial services | 2024 |
| LHT Property Holdings Ltd | Real estate | 2025 |
| LHT Swansea Limited | Real estate | 2017 |
| Li'L Legend Studio Ltd | Professional & scientific | 2020 |
| Li-In Pilates Ltd | Wholesale & retail | 2025 |
| Liana Takeaway Ltd | Hospitality | 2017 |
| Liberate HR Limited | Administrative & support | 2011 |
| Liberty Car Sales Ltd | Wholesale & retail | 2012 |
| Liberty Containers & Storage Holdings Limited | Financial services | 2021 |
| Liberty Containers & Storage Limited | Transport & logistics | 2021 |
| Liberty Control Services Limited | Construction | 2021 |
| Liberty Home Design Limited | Construction | 2010 |
| Liberty Legal Protect Limited | Financial services | 2015 |
| Liberty Motor Trade Ltd | Wholesale & retail | 2021 |
| Liberty Properties (Homes) Limited | Construction | 1985 |
| Liberty Rescue Ltd | Professional & scientific | 2020 |
| Liberty Resources Ltd | Hospitality | 2025 |
| Liberty Structural Engineering Limited | Construction | 2018 |
| Liberty Tiles Studio Limited | Wholesale & retail | 2013 |
| Life at NO.27 C.I.C. | Agriculture & fishing | 2018 |