| Indigo Mentoring Ltd. | Administrative & support | 2017 |
| Indigofinch Ltd | Wholesale & retail | 2026 |
| Industrial GRP Holdings Limited | Financial services | 2024 |
| Industrial GRP Limited | Manufacturing | 1999 |
| Inflated Productions Ltd | Other services | 2017 |
| Inspirational Hair Design Ltd | Other services | 2015 |
| Integrated Business Services Limited | Professional & scientific | 1989 |
| Intouched Limited | Other services | 2025 |
| Intratech Engineering Limited | Professional & scientific | 2018 |
| Investment Portal Limited | Real estate | 2018 |
| Iplanning Holdings Ltd | Financial services | 2025 |
| Iresha Superstore Ltd | Wholesale & retail | 2025 |
| Ironcore Welding and Fabrication Ltd | Other services | 2025 |
| Irwyn and Sons Ground Works Ltd | Construction | 2021 |
| Isherwood Investments Ltd | Extraterritorial | 2018 |
| Isnatur Ltd | Education | 2025 |
| Istma Consult Ltd | Education | 2025 |
| J & E Freight Ltd | Transport & logistics | 2024 |
| J a Davies Haulage Limited | Transport & logistics | 2017 |
| J F Tuning Ltd | Wholesale & retail | 2025 |
| J Jones Metal Recycling Limited | Wholesale & retail | 2025 |
| J L Insurance Solutions Ltd | Financial services | 2020 |
| J O Morris Limited | Construction | 1990 |
| J.Wilson Carpentry and Roofing Contractors Limited | Manufacturing | 2020 |
| JA Dining Ltd | Hospitality | 2026 |
| Jacksons Electrical Services Ltd | Construction | 2013 |
| JAO Property Limited | Manufacturing | 2007 |
| Jasper Property Management Limited | Real estate | 2009 |
| Jayden INK House Ltd | Other services | 2024 |
| JC International Trading Ltd | Wholesale & retail | 2024 |
| Jdss Limited | Real estate | 2005 |
| Jelfs Health & Herbal Limited | Wholesale & retail | 2005 |
| Jenkins Photography Limited | Professional & scientific | 2010 |
| Jenko's Gems Ltd | Wholesale & retail | 2024 |
| JER Properties Limited | Real estate | 2023 |
| JES Property Holdings Limited | Households | 2021 |
| JET Pumps UK Ltd | Mining & quarrying | 1997 |
| Jetsweep Limited | Water & waste | 1988 |
| Jettycare Ltd | Manufacturing | 2026 |
| JLC Installations and Maintenance Ltd | Construction | 2025 |
| JLH Investment Holdings Ltd | Financial services | 2026 |
| JLH Property Investments 1 Ltd | Real estate | 2026 |
| Joball Ltd | Health & social care | 2021 |
| Jones Brothers Fabrication Ltd | Manufacturing | 2013 |
| Jones D Limited | Wholesale & retail | 2018 |
| Jones Driver Services Ltd | Transport & logistics | 2025 |
| Jones Town Planning Ltd | Professional & scientific | 2012 |
| Jpeg Property Group Ltd | Construction | 2026 |
| JPR Design & Build Ltd | Construction | 2025 |
| JT Holdings (Wales) Ltd | Professional & scientific | 2005 |
| K & S Shop Ammanford Ltd | Wholesale & retail | 2025 |
| K C Scaffolding (Wales) Ltd | Construction | 2006 |
| K&R Mobile Disco Limited | Arts & recreation | 2022 |
| Kang’S Transport Ltd | Transport & logistics | 2021 |
| Karitree Limited | Manufacturing | 2018 |
| Kayvic Limited | Manufacturing | 2025 |
| Kelika Holdings Ltd | Real estate | 2022 |
| Kennedy Management Ltd | Professional & scientific | 2021 |
| Keys Property Management (Wales) Limited | Real estate | 2016 |
| Kieran Isherwood Electrical Services Ltd | Construction | 2022 |
| Kinnescash Limited | Real estate | 2024 |
| Kris of ALL Trades Ltd | Administrative & support | 2023 |
| KWD Services Ltd | Manufacturing | 2025 |
| L J Elliott Construction Limited | Construction | 2025 |
| LA Providence Garages Ltd | Wholesale & retail | 2016 |
| LA Tecnica UK Limited | Wholesale & retail | 2016 |
| Lacey Property Limited | Real estate | 2025 |
| Laleston Project Management Limited | Professional & scientific | 2007 |
| Lana Turner Smile Vintage Ltd | Wholesale & retail | 2024 |
| Landy Clinic Ltd | Manufacturing | 2025 |
| Lanter Ltd | Wholesale & retail | 2021 |
| Laservectors Ltd | Manufacturing | 2021 |
| Laura J Craddock Limited | Professional & scientific | 2015 |
| Lausons Cleaning Ltd | Administrative & support | 2022 |
| Lausons Property Management Ltd | Real estate | 2021 |
| LBS Builders Merchants Limited | Manufacturing | 1931 |
| LBS Holdings (UK) Limited | Wholesale & retail | 2004 |
| LCE Resin Specialists Ltd | Construction | 2021 |
| Lcprime Ltd | Professional & scientific | 2022 |
| LEE Bentley Cars of Garnant Ltd | Wholesale & retail | 2018 |
| Lendek Construction Limited | Construction | 2025 |
| Lennel Property Limited | Real estate | 2000 |
| Lennios Ammanford Limited | Hospitality | 2025 |
| Lexor Technologies Limited | Professional & scientific | 1993 |
| Lgbt Limited | Construction | 2009 |
| LGD Construction Limited | Construction | 2018 |
| LGD Entertainment Ltd | Arts & recreation | 2026 |
| LGD Spurway Holdings Ltd | Financial services | 2026 |
| Lignum Joinery Ltd | Manufacturing | 2021 |
| Lignum Joinery Services Ltd | Manufacturing | 2017 |
| Lindys Bach Childcare Ltd | Health & social care | 2018 |
| Llandybie Taxis Ltd | Transport & logistics | 2025 |
| Llandyfan Camping Ltd | Agriculture & fishing | 2024 |
| Lloches CIC | Other services | 2025 |
| Lloyd Roofing & Carpentry Ltd | Construction | 2018 |
| Llwynbrain Falcons Ltd | Agriculture & fishing | 2025 |
| Llys Dolwerdd Management Company Limited | Real estate | 2019 |
| Llys Y MOR CYF | Real estate | 2018 |
| LMS Investments Ltd | Real estate | 2019 |
| LN8 Solutions Limited | Information & communication | 2018 |