| JWP Tank Services Ltd | Professional & scientific | 2023 |
| Kaad in Environmental Health Ltd | Administrative & support | 2002 |
| Karmic Synergy Limited | Information & communication | 2019 |
| Kaszana Limited | Wholesale & retail | 2015 |
| Key Mortgage Hub Ltd | Financial services | 2026 |
| KFB Global Ltd | Manufacturing | 2019 |
| Kindred Motion Pictures Limited | Information & communication | 2023 |
| Kinetics Industrial Limited | Arts & recreation | 2005 |
| Kinetik Drinks Ltd | Manufacturing | 2025 |
| Kitchens of Pride Limited | Extraterritorial | 2001 |
| KJ Hart Building Ltd | Construction | 2014 |
| KM Taste Ltd | Hospitality | 2018 |
| Kneeskeit Limited | Manufacturing | 2026 |
| Knowtra Ltd | Information & communication | 2007 |
| Kouji Limited | Arts & recreation | 2023 |
| KP Site Management Ltd | Professional & scientific | 2012 |
| KS Cargeau Ltd | Transport & logistics | 2020 |
| Kudo Global Limited | Professional & scientific | 2019 |
| L.W.Properties Limited | Real estate | 2003 |
| LA Wind Group Ltd | Construction | 2024 |
| Lamb Specialist Engineering Limited | Professional & scientific | 2006 |
| Lance Deckwa Construction Ltd | Construction | 2019 |
| Lands END Tyres & Exhausts Ltd. | Real estate | 1985 |
| Langport Ltd | Administrative & support | 2025 |
| Language for Business Ltd | Professional & scientific | 2015 |
| Last Chapter Limited | Information & communication | 2015 |
| LAT Lettings Ltd | Real estate | 2019 |
| Lauto Ltd | Wholesale & retail | 2025 |
| LCR Motors Limited | Wholesale & retail | 2014 |
| Leaf Health Hitchin Ltd | Wholesale & retail | 2004 |
| Lean Enterprise Academy Ltd | Professional & scientific | 2002 |
| Leary Offshore Ltd | Professional & scientific | 2024 |
| LED Ceilings Limited | Extraterritorial | 2013 |
| Legal Connections Limited | Information & communication | 2025 |
| Leisure Investments (UK) Ltd | Extraterritorial | 2014 |
| Leisurescape Ltd | Wholesale & retail | 2022 |
| LEJ Electrical Ltd | Construction | 2026 |
| Lemon Grass Thai Massage Limited | Health & social care | 2021 |
| Lemon Studios Dance and Fitness Ltd | Arts & recreation | 2019 |
| Leo's Bar & Grill Limited | Hospitality | 2020 |
| Lerpwl Living Ltd | Real estate | 2024 |
| LET There BE Light Ltd | Extraterritorial | 2018 |
| LGM Building Ltd | Construction | 2019 |
| Liberty Mills Ltd | Education | 2024 |
| Liberty Solutions Limited | Professional & scientific | 2012 |
| Life Liberated Ltd | Health & social care | 2023 |
| Limitless Wind Ltd | Extraterritorial | 2024 |
| Linden Parks Ltd | Wholesale & retail | 2023 |
| Linear Developments (Wales) Ltd | Construction | 2020 |
| Linear Renewables Limited | Construction | 2024 |
| Lineback Limited | Wholesale & retail | 1987 |
| Linney Cooper Limited | Wholesale & retail | 1964 |
| Liodelyn Ltd | Hospitality | 2018 |
| Lismar Ltd | Administrative & support | 2021 |
| Little Lighthouse Ltd | Professional & scientific | 2018 |
| Little Lily Clothing Store Limited | Wholesale & retail | 2022 |
| Live Technologies Limited | Information & communication | 2005 |
| Livetech Ltd | Information & communication | 2014 |
| Liveware Resources Limited | Professional & scientific | 1996 |
| Llanberis Bike Hire Limited | Arts & recreation | 2010 |
| Llandudno Alliance Lettings Ltd | Hospitality | 2021 |
| Llandudno Alliance Limited | Wholesale & retail | 2005 |
| Llandudno Boutique Hotel Ltd | Hospitality | 2018 |
| Llandudno Breaks Limited | Hospitality | 2024 |
| Llandudno Building & Workmens Dwellings Company Limited(The) | Construction | 1886 |
| Llandudno Carpets and Furniture Limited | Extraterritorial | 2014 |
| Llandudno Central Ltd | Hospitality | 2024 |
| Llandudno Cleaning Ltd | Administrative & support | 2022 |
| Llandudno Community Events CIC | Arts & recreation | 2025 |
| Llandudno Constitutional Club Limited(The) | Real estate | 1923 |
| Llandudno Cricket Club Ltd | Arts & recreation | 2026 |
| Llandudno Elderly People's Welfare Society | Other services | 1984 |
| Llandudno FC | Arts & recreation | 2010 |
| Llandudno FC in the Community | Arts & recreation | 2010 |
| Llandudno Golf Club (Maesdu) Limited | Arts & recreation | 1974 |
| Llandudno Holdings LLP | | 2015 |
| Llandudno Investments LLP | | 2014 |
| Llandudno Karate Ltd | Other services | 2015 |
| Llandudno Land Trains Ltd | Transport & logistics | 2023 |
| Llandudno Merry Moon Bubble Tea Ltd | Hospitality | 2022 |
| Llandudno Mini Market Limited | Wholesale & retail | 2026 |
| Llandudno Nice Food Ltd | Hospitality | 2022 |
| Llandudno Nursery and Pre-School Ltd | Health & social care | 2024 |
| Llandudno Sailing Club Limited | Arts & recreation | 1976 |
| Llandudno Specsavers Limited | Wholesale & retail | 1994 |
| Llandudno Subs Limited | Hospitality | 2023 |
| Llandudno Taxis Ltd | Transport & logistics | 2026 |
| Llandudno Transport & Storage Company Limited | | 1992 |
| Llandudno Vaults Ltd | Arts & recreation | 2023 |
| Llandudno Visionplus Limited | Wholesale & retail | 1994 |
| Llandudno Visitor Centre Limited | Real estate | 2019 |
| Llandudno Welsh Rugby Union Football Club Limited | Arts & recreation | 1977 |
| Llandudno Wholesale Ltd | Wholesale & retail | 2003 |
| Llanfairfechan Flooring Ltd | Administrative & support | 2016 |
| Lleone Limited | Extraterritorial | 2013 |
| Llewelyn House Management Limited | Households | 1991 |
| Lloyds Residential Lettings Ltd | Real estate | 2021 |
| Llys Maelgwn Limited | Households | 1973 |
| London Coffee Roasters Ltd | Extraterritorial | 2013 |
| Longacres (NW) Limited | Transport & logistics | 2020 |