| Little West Apartments (Freehold) Limited | Households | 2019 |
| Littlewest Limited | Information & communication | 2019 |
| Live to Travel Ltd | Administrative & support | 2020 |
| Lizzi Limited | Wholesale & retail | 2025 |
| LJ Owen Agencies Limited | Wholesale & retail | 2019 |
| LJ South Property Ltd | Real estate | 2019 |
| LJA Training Ltd | Information & communication | 2024 |
| Ljm&C Limited | Health & social care | 2023 |
| LK Property Developments Ltd | Construction | 2020 |
| LKF Brickwork Ltd | Construction | 2021 |
| Llampha Farms Ltd | Agriculture & fishing | 2024 |
| Llangeinor Arms Country PUB and Restaurant Ltd | Hospitality | 2020 |
| Llangeinor Football Ltd | Education | 2019 |
| Llanharan Property Holdings Ltd | Real estate | 2025 |
| Llanw Property Services Limited | Real estate | 2023 |
| Llanwynno Energy Ltd | Energy | 2017 |
| Llanwynno Green Power Limited | Energy | 2025 |
| LLE Swshi Limited | Hospitality | 2024 |
| Llorrells Construction Services Ltd | Construction | 2023 |
| Lloyd Associates Limited | Professional & scientific | 1993 |
| Lloyd Securities Limited | Real estate | 1996 |
| Lloyd Williams Photography Limited | Professional & scientific | 2019 |
| Lloyds Aerospace Ltd | Transport & logistics | 2009 |
| Lloyds Construction Limited | Real estate | 2006 |
| Lloyds Scaling Limited | Real estate | 2025 |
| Llynfi PUB Co Ltd. | Extraterritorial | 2023 |
| Llynfi Valley 11-25 Youth Project Ltd | Health & social care | 1997 |
| Llynfi Valley Amateur Boxing Club Limited | Arts & recreation | 2022 |
| Llys Hendy Consulting Limited | Professional & scientific | 2019 |
| Llŷr Limited | Financial services | 2024 |
| LMA Law Ltd | Administrative & support | 2024 |
| LMC Hospitality Ltd | Hospitality | 2025 |
| LMF Hospitality Limited | Hospitality | 2025 |
| Lmfd RO Ltd | Transport & logistics | 2016 |
| LMH Group Ventures Ltd | Financial services | 2026 |
| LMJ Clear Ears Limited | Health & social care | 2025 |
| Lnae Limited | Other services | 2026 |
| Loaded Spudz Limited | Hospitality | 2025 |
| Local Energy Supply Systems Limited | Professional & scientific | 2009 |
| Location 1 Group Ltd | Financial services | 2019 |
| Location One Ltd | Water & waste | 2006 |
| Location Solutions Wales Ltd | Information & communication | 2019 |
| Locks in the City Limited | Administrative & support | 2015 |
| Loftylets Ltd | Real estate | 2019 |
| Lois James Wilson Properties Ltd | Real estate | 2022 |
| London and Home Counties Lettings Ltd | Real estate | 2020 |
| Londonu Ltd | Wholesale & retail | 2026 |
| Lonjohn Limited | Real estate | 2024 |
| Loop Furniture Ltd | Wholesale & retail | 2019 |
| Loosemore Properties Limited | Real estate | 2019 |
| Lordburn Limited | Extraterritorial | 2025 |
| Lordcare Limited | Information & communication | 2024 |
| Lordreed Limited | Extraterritorial | 2024 |
| Lotsa Brands Limited | Extraterritorial | 2022 |
| Love Lagree Limited | Arts & recreation | 2023 |
| Love U 2 Ltd | Wholesale & retail | 2020 |
| Lowan's (Wales) Limited | Real estate | 2021 |
| Lowen Glas Ltd | Professional & scientific | 2025 |
| LP Safety &Compliance Limited | Professional & scientific | 2026 |
| LRJ Consultants Limited | Professional & scientific | 2017 |
| LRJ Estates Ltd | Real estate | 2020 |
| LS Industrial Services Ltd | Professional & scientific | 2024 |
| LS Property and Investments Ltd | Real estate | 2025 |
| LSK Property Services Ltd | Real estate | 2024 |
| LT Survey Solutions Ltd | Professional & scientific | 2023 |
| LT Vehicle Management Ltd | Administrative & support | 2025 |
| LTT Construction Ltd | Construction | 2021 |
| Luca Logistics Ltd | Wholesale & retail | 2025 |
| Lucida Property Sales & Lettings Ltd | Real estate | 2016 |
| Luckymc Limited | Hospitality | 2025 |
| Lucys Best Bites Limited | Hospitality | 2024 |
| Luffman Developments Limited | Real estate | 2022 |
| Lufthold Cayman Ltd | Professional & scientific | 2023 |
| Luger Properties Ltd | Real estate | 2007 |
| Lula Health Ltd | Wholesale & retail | 2025 |
| Lutra Health Limited | Information & communication | 2021 |
| Luxe Aura Salon Limited | Other services | 2026 |
| Luxidian Ltd | Professional & scientific | 2025 |
| Luxury Leisure Holdings Limited | Financial services | 2002 |
| LW Geomatics Limited | Construction | 2025 |
| LWC Restaurant Ltd | Hospitality | 2019 |
| Lynnmire Limited | Extraterritorial | 2026 |
| Lynwood Park Property Ltd | Real estate | 2023 |
| M & C Civils (Bridgend) Limited | Construction | 2006 |
| M & C Civils Limited | Construction | 2015 |
| M & I Natural Limited | Wholesale & retail | 2023 |
| M & M Catering Equipment Limited | Manufacturing | 2008 |
| M B Specialist Limited | Wholesale & retail | 2004 |
| M Csetnek Ltd | Transport & logistics | 2021 |
| M D Autos Limited | Wholesale & retail | 2018 |
| M G Farrier Services Ltd | Administrative & support | 2017 |
| M J & E L Morgan Ltd | Wholesale & retail | 2009 |
| M J Wilson Contracting Ltd | Construction | 2020 |
| M Jaques Ltd | Manufacturing | 2002 |
| M P Cars Ltd | Wholesale & retail | 1999 |
| M P Services (S.W) Ltd | Manufacturing | 2013 |
| M Tooze Properties Limited | Real estate | 2023 |
| M&B Construction Contractors Ltd | Construction | 2021 |
| M&L Engineering Solutions Limited | Construction | 2015 |
| M&S Vehicle Services Ltd | Wholesale & retail | 2005 |