| Krsl Ltd | Administrative & support | 2022 |
| KS Cheema Ltd | Hospitality | 2020 |
| KSA Home Developments Ltd | Real estate | 2025 |
| Ksdg Limited | Manufacturing | 2023 |
| KSG Civils Limited | Construction | 2024 |
| KSL Beauty & Aesthetics Limited | Other services | 2023 |
| KSM Consultancy Limited | Information & communication | 1992 |
| KSW Productions Ltd. | Other services | 2016 |
| KTG Services Ltd | Hospitality | 2026 |
| KTL Plumbing & GAS Ltd | Construction | 2026 |
| Kudos International Network Limited | Other services | 2012 |
| Kudu Group Ltd | Professional & scientific | 2026 |
| Kuidpro UK Limited | Financial services | 2026 |
| Kurd Salon Ltd | Other services | 2025 |
| Kurdish Bodyworker Ltd | Wholesale & retail | 2024 |
| Kurdish Restaurant (Swansea) Ltd | Hospitality | 2025 |
| Kurdish Restaurant SA1 Limited | Hospitality | 2026 |
| Kursar Ltd | Information & communication | 2016 |
| Kusa Connect Ltd | Professional & scientific | 2021 |
| KWB Legal Services Limited | Professional & scientific | 2024 |
| Kwmd Homes Ltd | Real estate | 2019 |
| Kwmd Property Solutions Ltd | Real estate | 2017 |
| Kwris Mount Limited | Real estate | 2026 |
| KXX Risk Ltd | Administrative & support | 2019 |
| KYA Property Ltd | Real estate | 2023 |
| Kyara Limited | Professional & scientific | 2015 |
| Kylepes Ltd | Health & social care | 2023 |
| Kynance Invest Ltd | Financial services | 2022 |
| Kyphi Ltd | Wholesale & retail | 2025 |
| Kyte Enterprises Limited | Financial services | 2018 |
| L & R Buchanan Care Services Ltd | Administrative & support | 2015 |
| L & R Property Development Limited | Real estate | 2012 |
| L a Alarms (Cardiff) Ltd | Extraterritorial | 2022 |
| L a Alarms (Swansea) Ltd | Extraterritorial | 2022 |
| L and AA Holding Limited | Construction | 2024 |
| L and T Hire and Supplies Limited | Administrative & support | 2012 |
| L Begley Ltd | Administrative & support | 2019 |
| L C Plumbing and Bathrooms Ltd | Construction | 2012 |
| L C Stores Limited | Wholesale & retail | 2026 |
| L Dower Electrics Ltd | Construction | 2017 |
| L Francis Logistics Limited | Transport & logistics | 2022 |
| L G Murphy Ltd | Construction | 2000 |
| L H Hair Studio Limited | Other services | 2020 |
| L J D Productions Limited | Information & communication | 2008 |
| L J Engineering Ltd | Construction | 2025 |
| L J Imaging Ltd | Health & social care | 2018 |
| L J Project Consultancy Limited | Construction | 2017 |
| L Jonathan Ltd | Wholesale & retail | 2021 |
| L Jones Transport Limited | Transport & logistics | 2017 |
| L L Carpentry (Swansea) Ltd | Construction | 2021 |
| L M G Investments 2019 Ltd | Real estate | 2019 |
| L Murphy Building Ltd | Water & waste | 2026 |
| L O Creations Limited | Other services | 2016 |
| L O Promotions Limited | Other services | 2021 |
| L P Body Repairs Ltd | Wholesale & retail | 2025 |
| L P O Gardening Services Limited | Administrative & support | 2024 |
| L S Sisters Ltd | Other services | 2020 |
| L&C Properties 24 Limited | Real estate | 2024 |
| L&J Autoz Ltd | Manufacturing | 2014 |
| L&M Property Group Ltd | Real estate | 2026 |
| L&W Electrical Limited | Energy | 2018 |
| L'Osteria Toscana Ltd | Hospitality | 2025 |
| L. Noakes Limited | Professional & scientific | 1981 |
| L. T. C. Mobility Ltd | Wholesale & retail | 2008 |
| L.A.C. Conveyor Systems Limited | Administrative & support | 2007 |
| L.A.E Group Limited | Financial services | 2025 |
| L.D Building & Waste Clearance Limited | Construction | 2025 |
| L.G Endurance Limited | Construction | 2023 |
| L.G. Murphy (Swansea) Limited | Construction | 1972 |
| L.H Hiab & Recovery Limited | Wholesale & retail | 2026 |
| L.S Refurbishments Ltd | Construction | 2020 |
| L10 Rentals Ltd | Administrative & support | 2025 |
| L10 Services Group Ltd | Transport & logistics | 2020 |
| L16 Management Ltd | Real estate | 2021 |
| L4 Cafe Ltd | Hospitality | 2026 |
| LA Buckly Ltd | Administrative & support | 2018 |
| LA Dolce Vita (Mumbles) Ltd | Hospitality | 2025 |
| LA Energy Ltd | Construction | 2025 |
| LA Estates & Holdings Ltd | Real estate | 2026 |
| LA Frenda Limited | Hospitality | 2019 |
| LA Mucca Pazza Ltd | Hospitality | 2025 |
| LA Petite Vintage Store Ltd | Wholesale & retail | 2020 |
| LAB Engineering (South Wales) Limited | Manufacturing | 2001 |
| Labl Ltd | Manufacturing | 2019 |
| Labyrinth Climbing Ltd | Arts & recreation | 2022 |
| LAC Solutions Ltd | Information & communication | 2019 |
| Lace Auto Centre Limited | Wholesale & retail | 2025 |
| LAD Builds Ltd | Construction | 2024 |
| Lads and Dads Welshpool Limited | Other services | 2020 |
| Ladybug CYF. | Wholesale & retail | 2018 |
| Lafina Group Ltd | Construction | 2019 |
| Lagoon & Co Swansea Ltd | Hospitality | 2019 |
| Lagoon Holdings Ltd | Real estate | 2026 |
| LAH Companies Ltd | Administrative & support | 2018 |
| Lakaz Lavi Ltd | Wholesale & retail | 2026 |
| Lakeside Day Nursery Limited | Health & social care | 2011 |
| Lakeside Flood Solutions Ltd | Construction | 2016 |
| Lakeside Security Swansea Ltd | Administrative & support | 2016 |
| Lakeside Spas Limited | Wholesale & retail | 2013 |
| Lakeside Technology Limited | | 1989 |