| L S J Building Limited | Construction | 2025 |
| L W UFH Heating Limited | Construction | 2018 |
| L&R W Limited | Manufacturing | 2003 |
| L4 Apartments Ltd | Households | 2017 |
| Labrats (Legacy of the Atomic Bomb. Recognition for Atomic Test Survivors) CIC | Other services | 2020 |
| Lambourne Holdings Limited | Real estate | 2001 |
| Lammas Pizza Ltd | Hospitality | 2019 |
| Lammas Street Convenience Shop Ltd | Wholesale & retail | 2021 |
| Lammas Street Store Limited | Wholesale & retail | 2018 |
| LAN Farm Ltd | Agriculture & fishing | 2019 |
| Landeg Garage Limited | Wholesale & retail | 2022 |
| Landmark Place Properties Limited | Real estate | 2010 |
| Lanes Cars Workshops Limited | Wholesale & retail | 2015 |
| Lanfawr Developments Ltd | Construction | 2008 |
| Langdon Mill Farms Limited | Agriculture & fishing | 2013 |
| Larenim Ltd | Mining & quarrying | 2026 |
| Largocom Logistics L.P. | | 2018 |
| Last Wishes Mobile VET Limited | Professional & scientific | 2023 |
| Lattimore Retreats Ltd | Hospitality | 2025 |
| Laugharne Bread Limited | Manufacturing | 2013 |
| Laugharne Cabs Limited | Transport & logistics | 2024 |
| Laugharne Lets Limited | Hospitality | 2026 |
| Laugharne Traders Limited | Wholesale & retail | 2019 |
| Laugharne Travel Limited | Transport & logistics | 2015 |
| LBJ-MC2 Ltd | Construction | 2022 |
| Lcvh Services Ltd | Administrative & support | 2026 |
| LDC Renovations Limited | Construction | 2023 |
| LDCQACQ23 Ltd | Construction | 2025 |
| LDI Limited | Professional & scientific | 2014 |
| Learn 2BU Ltd | Education | 2015 |
| LEE Fern Surveys Limited | Other services | 2026 |
| Legis Ltd | Health & social care | 2025 |
| Leigh H Engineering Limited | Professional & scientific | 2025 |
| Leisure Homes Limited | Real estate | 2012 |
| Lens 360 Limited | Extraterritorial | 2016 |
| Level Groundworks Ltd | Construction | 2023 |
| Lewis Brothers Contracting Limited | Agriculture & fishing | 2022 |
| Lewis Carpentry & Construction Ltd | Construction | 2024 |
| Lewis Farm Holdings UK Ltd | Agriculture & fishing | 2018 |
| Lewis News Limited | Real estate | 2004 |
| LFR Design Ltd | Professional & scientific | 2019 |
| LH Capital Investments Ltd | Financial services | 2019 |
| LHP Accountants Ltd | Professional & scientific | 2011 |
| LHP Audit Ltd | Professional & scientific | 2020 |
| LHP Auditors Ltd | Professional & scientific | 2017 |
| LHP JDR Limited | Professional & scientific | 2022 |
| LHP Probate Ltd | Professional & scientific | 2020 |
| LHP Virtual Finance Ltd | Professional & scientific | 2020 |
| LHP Wealth Management Ltd | Professional & scientific | 2020 |
| Lhproducts Ltd | Wholesale & retail | 2023 |
| Libera Digital Ltd | Professional & scientific | 2023 |
| Liberty JAI Limited | Professional & scientific | 2018 |
| Life Protection Centre Ltd | Financial services | 2019 |
| Lifestyle Business Design Limited | Professional & scientific | 2009 |
| Lifestyles (Wales) Limited | Health & social care | 2004 |
| Lightcourt Limited | Hospitality | 1987 |
| Likeafish Swim School Limited | Education | 2011 |
| Limes GS Limited | Agriculture & fishing | 2014 |
| Limitless Vapes Carmarthen Limited | Wholesale & retail | 2024 |
| Limitless Vapes Limited | Wholesale & retail | 2023 |
| Lionmax Import L.P. | | 2018 |
| Lionstar Logistics L.P. | | 2018 |
| Lisa Barry Online Limited | Professional & scientific | 2020 |
| Lisa Fearn Limited | Hospitality | 2017 |
| Little Bambinos Nursery Ltd | Administrative & support | 2017 |
| Little Mill Equestrian Limited | Agriculture & fishing | 2021 |
| Little Mill Events Limited | Arts & recreation | 2021 |
| Littlemoor Equestrian Centre Ltd | Other services | 2020 |
| Live Life Official Ltd | Wholesale & retail | 2017 |
| LIZ Crane Ltd | Households | 2025 |
| LJC Property Developments Ltd | Construction | 2026 |
| Llaeth Derlwyn Ltd | Hospitality | 2020 |
| Llaeth Maeth Ltd | Manufacturing | 2021 |
| Llandeilo Glamping Ltd | Hospitality | 2025 |
| Llandysul Motor Club Limited | Arts & recreation | 2006 |
| Llanelli Performance Centre Ltd | Arts & recreation | 2021 |
| Llanelli Performance Unit Limited | Arts & recreation | 2023 |
| Llangynin Management Company Limited | Households | 2006 |
| Llanmiloe and District Community Association Ltd | Health & social care | 2006 |
| Llanmiloe Holdings Limited | Real estate | 2020 |
| Llansadurnen Farm Ltd | Agriculture & fishing | 2009 |
| Llansteffan Castle Ltd | Arts & recreation | 2016 |
| Llansteffan Sports Club | Arts & recreation | 2005 |
| Llansteffan Village Stores Ltd | Hospitality | 2026 |
| Llanungar Fach Caravan Park Ltd | Hospitality | 2014 |
| Llawfeddyg Orthopaedics Limited | Health & social care | 2011 |
| Llawn Cariad Limited | Wholesale & retail | 2023 |
| Llewellyn Humphreys (Surveyors) Ltd | Professional & scientific | 2026 |
| Llwynbrain Ltd | Financial services | 2019 |
| Llwyndu Farm Limited | Agriculture & fishing | 2004 |
| Llwyngwair Properties Limited | Real estate | 1964 |
| Llyfrau Llafar Cymru | Other services | 2011 |
| Llygaid CYF | Health & social care | 2017 |
| Llys Trefin CYF | Construction | 2024 |
| Llys Y Coed Ltd | Real estate | 2021 |
| Llystyn Construction Limited | Construction | 2010 |
| LO Dinos Property Ltd | Real estate | 2021 |
| Lolfa CYF | Hospitality | 2020 |
| Lolfa Llandeilo CYF | Hospitality | 2022 |
| Londolux L.P. | | 2018 |