| Lifeline Plumbing Limited | Construction | 2003 |
| Lifestyle Express Ltd | Wholesale & retail | 2012 |
| Life’S a Stitch Ltd | Wholesale & retail | 2023 |
| Lift and Shift (South Wales) Limited | Extraterritorial | 2009 |
| Lifting and Shifting Limited | Transport & logistics | 2025 |
| Light Co Holdings Limited | Financial services | 2025 |
| Light Co Properties Limited | Real estate | 2026 |
| Light Engine DRY Hire Limited | Administrative & support | 2019 |
| Light Power Engineering Ltd | Construction | 2018 |
| Lighthouse Children's Therapy Service Limited | Other services | 2019 |
| Lighthouse Electrical (Wales) Limited | Manufacturing | 2014 |
| Lightwork Design Limited | Extraterritorial | 2021 |
| Lilleshall Cricket Club Limited | Arts & recreation | 2019 |
| Lilleshall Sports Injury Rehab Limited | Health & social care | 2005 |
| Lily Dudes Ltd | Wholesale & retail | 2021 |
| Lily White Jewellery Ltd | Wholesale & retail | 2025 |
| Lima Associates (South) Limited | Other services | 2007 |
| Lime Tree Consultancy Services Ltd | Real estate | 2023 |
| Limecross Solutions Limited | Information & communication | 2004 |
| Liminal Coaching Limited | Professional & scientific | 2009 |
| Limkongadz Ltd | Health & social care | 2022 |
| LIN Sheng Limited | Hospitality | 2026 |
| Linah Properties Ltd | Real estate | 2024 |
| Lincoln Willows Ltd | Financial services | 2023 |
| Lindale Building Services Limited | Construction | 1992 |
| Lindens (IOW) Limited | Extraterritorial | 2015 |
| Linea Resourcing Limited | Administrative & support | 2002 |
| Linetop Limited | Manufacturing | 1983 |
| Linford Engineering Consultants Limited | Professional & scientific | 2019 |
| Lingarder Limited | Information & communication | 2018 |
| Lingo Binge Ltd | Professional & scientific | 2025 |
| Lingold Limited | Financial services | 2015 |
| Linington Court Management Company Limited | Households | 1986 |
| LINKS4LIFE Limited | Manufacturing | 2024 |
| Linkway Software Limited | Information & communication | 2010 |
| Linnells Limited | Real estate | 2001 |
| Lintlehlapisi Limited | Health & social care | 2017 |
| Linx Garment Solutions Ltd | Wholesale & retail | 2024 |
| Linx Solutions Ltd | Transport & logistics | 2016 |
| Lion Wales Limited | Transport & logistics | 2004 |
| Liquid Measure Limited | Wholesale & retail | 2003 |
| Liquorlink Limited | Wholesale & retail | 2025 |
| Lisa Jayne Art & Illustration Limited | Arts & recreation | 2018 |
| Lisa Pryce-Jones Ltd | Health & social care | 2026 |
| Lisa's Dream Chasers Ltd | Professional & scientific | 2025 |
| Lismp Ltd | Health & social care | 2021 |
| Liswerry Property Management Ltd | Real estate | 2018 |
| Lite & Loaded Ltd | Hospitality | 2024 |
| Little Acres Childcare Centre Limited | Health & social care | 2021 |
| Little Gardeners Club Ltd | Wholesale & retail | 2026 |
| Little Green Lizard Publications Ltd | Information & communication | 2021 |
| Little Hibba Ltd | Information & communication | 2020 |
| Little Leaf Salads Ltd | Agriculture & fishing | 2025 |
| Little London Developments Limited | Construction | 2014 |
| Little Milton Gardens Management Company Limited | Households | 2019 |
| Little Oaks Play Village Ltd | Education | 2018 |
| Little Oaks Town Ltd | Arts & recreation | 2025 |
| Little Rasoi Ltd | Hospitality | 2026 |
| Little Scamp Limited | Hospitality | 2025 |
| Little Stars Abercarn Ltd | Administrative & support | 2016 |
| Little Stars Rogerstone Limited | Health & social care | 2025 |
| Little Tots Play Village Newport Ltd | Hospitality | 2025 |
| Little Whitcombe Farm Limited | Extraterritorial | 2016 |
| Little Wins Marketing Co. Limited | Professional & scientific | 2026 |
| Littleton Murdoch Ltd | Professional & scientific | 2014 |
| Live for Holidays Ltd | Administrative & support | 2021 |
| Live Productions Ltd | Information & communication | 2025 |
| Living Grace Limited | Health & social care | 2020 |
| LIZ Bruen SA EA Ltd | Health & social care | 2023 |
| Lizzie's Way Limited | Professional & scientific | 2019 |
| LJ Fire Ltd | Public administration | 2021 |
| LJC Social Work Services Ltd | Health & social care | 2023 |
| LJG Solutions Ltd | Construction | 2023 |
| LJH Hotbox & Grab Hire Ltd | Construction | 2026 |
| LJH Roofing Specialists Ltd | Construction | 2024 |
| LJM IT Consultancy Ltd | Information & communication | 2011 |
| LJN Construction Ltd | Construction | 2026 |
| LJW Properties Limited | Real estate | 2020 |
| LK Mortgage & Protection Consultancy Limited | Financial services | 2022 |
| Lkaia Properties Limited | Construction | 2015 |
| Lkco Engineering Ltd | Professional & scientific | 2026 |
| LKT Mobile Welding Limited | Manufacturing | 2025 |
| LL Wilsons Transport Ltd | Transport & logistics | 2011 |
| Ll's Kitchen Ltd | Hospitality | 2024 |
| Llain YR Eglwys Limited | Households | 2020 |
| Llancayo Properties Holdings Limited | Financial services | 2022 |
| Llancayo Properties Limited | Real estate | 2022 |
| Llanellen Properties Holdings Limited | Financial services | 2022 |
| Llanellen Properties Limited | Real estate | 2022 |
| Llanfair Construction Limited | Construction | 2007 |
| Llanhennock Property Management Limited | Real estate | 2009 |
| Llanover Properties Limited | Real estate | 1962 |
| Llanrumney Properties Limited | Real estate | 2025 |
| Llantarnam Store Ltd | Wholesale & retail | 2025 |
| Llantrisant Motors (1934) Limited | Transport & logistics | 1934 |
| Llanwern Coffee Co Ltd | Wholesale & retail | 2021 |
| Llanwern Golf Club Limited | Arts & recreation | 1950 |
| Llanwern Solar Services Ltd | Professional & scientific | 2023 |
| Llanwern Village Hotel and Bar Ltd | Hospitality | 2022 |
| Llew-A-Dor Residents Management Limited | Households | 2016 |