| Hot Tubs (Aberystwyth) Limited | Wholesale & retail | 2015 |
| Hughes 4 Homes Limited | Construction | 2014 |
| Human Assist Training and Support Ltd | Health & social care | 2017 |
| Humphrey Roberts & Bott CYF | Professional & scientific | 2018 |
| Huneez Ltd | Wholesale & retail | 2020 |
| HUT 2022 Ltd | Hospitality | 2021 |
| HUT 2026 Ltd | Hospitality | 2025 |
| HUW Evans Ltd | Professional & scientific | 2026 |
| HUW Richards Ltd | Information & communication | 2020 |
| HW Trees Ltd | Agriculture & fishing | 2018 |
| Hybu CIG Cymru-Meat Promotion Wales | Professional & scientific | 2003 |
| Hyddgen Homes Ltd | Construction | 2018 |
| Hyper Inc Ltd. | Information & communication | 2018 |
| I AM Lash Limited | Wholesale & retail | 2020 |
| IAN Morgan & SON LP | | 2011 |
| Iblossom Consulting Services Limited | Professional & scientific | 2026 |
| Ibohero Ltd | Manufacturing | 2022 |
| Idan Gavriel Ltd | Real estate | 2024 |
| Iechyd DA (Gwledig) Limited | Professional & scientific | 2013 |
| Iechyd DA Training Services Ltd | Professional & scientific | 2017 |
| IH2 Alliance Limited | Professional & scientific | 2025 |
| Inbuilt Marketing Ltd | Information & communication | 2025 |
| Indeg PR CYF | Other services | 2010 |
| Industrious Ltd | Manufacturing | 2018 |
| Inkwells (Aberystwyth) Limited | Wholesale & retail | 2014 |
| Innovis Breeding Sheep Limited | Agriculture & fishing | 2005 |
| Innovis Limited | Agriculture & fishing | 2003 |
| Insynch Business Services Limited | Information & communication | 2005 |
| International Live Events Group Limited | Education | 2020 |
| Iona Minerals Limited | Professional & scientific | 2022 |
| Ionize Limited | Information & communication | 2018 |
| Iron Phoenix CIC | Health & social care | 2026 |
| Italian Importers Ltd | Wholesale & retail | 2016 |
| J & SW Building Company Limited | Construction | 2018 |
| J G Corner Shop Ltd | Wholesale & retail | 2023 |
| J H Evans Ltd | Agriculture & fishing | 2026 |
| J M J Retail Ltd | Wholesale & retail | 2024 |
| J Thomas (Developments) Limited | Construction | 2003 |
| Jacob Fortune CYF | Administrative & support | 2026 |
| JC Small Engines Limited | Manufacturing | 2024 |
| Jclaridge Property Ltd | Households | 2024 |
| JD Property Lettings Limited | Real estate | 2025 |
| Jenkins Agri Limited | Agriculture & fishing | 2026 |
| Jenmar Properties Ltd | Real estate | 2005 |
| Jeremiah Holdings Limited | Financial services | 2024 |
| Jewellery House Limited | Wholesale & retail | 2003 |
| JLS Pubs Ltd | Hospitality | 2022 |
| Johns Construction Ltd | Construction | 2020 |
| Jones & Co (West) Limited | Real estate | 2012 |
| Joseph Builders Limited | Financial services | 2019 |
| Jt's Automotive Ltd | Wholesale & retail | 2025 |
| Justmaison Ltd | Real estate | 2019 |
| K J Roofing Services Aberystwyth LP | | 2020 |
| Kashrad Limited | Health & social care | 2021 |
| KD Day Ltd | Construction | 2026 |
| Keith Middleton Decorating Limited | Construction | 2004 |
| Keyblock Residents Management Limited | Hospitality | 1986 |
| Khop Chai DEU Ltd | Hospitality | 2024 |
| Khushal Singh Negi Limited | Wholesale & retail | 2025 |
| Kick the Bar Brewery Ltd | Professional & scientific | 2015 |
| Kicks and Klobber Ltd | Wholesale & retail | 2026 |
| Kitchen & Home Design Limited | Wholesale & retail | 2017 |
| KLF Laser Limited | Wholesale & retail | 2008 |
| KM Alvee Fast Food Ltd | Hospitality | 2025 |
| KMH Properties Ltd | Hospitality | 2019 |
| KMO Retail Ltd | Wholesale & retail | 2026 |
| Knockout Furniture Limited | Real estate | 2013 |
| Korina Limited | Hospitality | 2015 |
| Kreeping Inn Limited | Hospitality | 2001 |
| L & G Forestry Ltd | Agriculture & fishing | 2010 |
| L and R Building Contractors Limited | Construction | 2003 |
| L&A Real Estates Limited | Real estate | 2015 |
| Lafam Ltd | Hospitality | 2024 |
| Lafamiglia Pizza Limited | Hospitality | 2023 |
| Lahzest R & Tilly Limited | Wholesale & retail | 2025 |
| Lamont Management Company Limited | Real estate | 1989 |
| Land and Cloud Limited | Information & communication | 2017 |
| Lanehouse Developments Limited | Wholesale & retail | 1991 |
| Lawrence and Williams Construction Ltd. | Construction | 1998 |
| LEB Construction Limited | Construction | 2015 |
| LEB Investments Ltd | Real estate | 2020 |
| LES Jones Electrical Contractors Ltd | Construction | 2026 |
| Lewis Taxis CYF | Transport & logistics | 2012 |
| Libanus 1877 Ltd | Arts & recreation | 2017 |
| Liberty Builders Limited | Construction | 2019 |
| Life IS a Disco Productions Ltd | Information & communication | 2024 |
| Lighthouse Consultancy Limited | Professional & scientific | 2022 |
| Limecrabnewquay Ltd | Hospitality | 2023 |
| LJV Group Ltd. | Construction | 2019 |
| Llanbadarn Property Limited | Real estate | 2008 |
| Llanilar Developments Limited | Construction | 2016 |
| Llew DU 2020 Ltd | Hospitality | 2020 |
| Lluestwen Renewables Limited | Real estate | 2018 |
| Llyn Pendam Lake Ltd | Arts & recreation | 2022 |
| Llywela Thomas Bookkeeping & Payroll Services Limited | Professional & scientific | 2026 |
| Llywernog Mine (Resources) Ltd. | Arts & recreation | 1973 |
| Loadrated Ltd | Wholesale & retail | 2016 |
| Loch Foods Ltd | Hospitality | 2025 |
| Logoutt Limited | Manufacturing | 2020 |
| LONGZONE999 Ltd | Hospitality | 2020 |