| JON Bolton Consulting Ltd | Professional & scientific | 2015 |
| Jonellis Properties Ltd | Real estate | 2026 |
| Jordans Jungle Ltd | Hospitality | 2013 |
| Jowsa Consulting Ltd | Professional & scientific | 2016 |
| Jowsa Limited | Information & communication | 2013 |
| JS Construction Cumbria Ltd | Construction | 2024 |
| JSK Mechanical Services Limited | Wholesale & retail | 2020 |
| JSK1 Solutions Limited | Professional & scientific | 2012 |
| JTS Architectural Services Limited | Professional & scientific | 2017 |
| Judy Whiteside Limited | Arts & recreation | 2003 |
| Jules Restaurant Limited | Hospitality | 2026 |
| Jungle Cats Engineering Limited | Professional & scientific | 2022 |
| JWM (Cumbria) Ltd | Wholesale & retail | 2017 |
| K Adams & SON Builders Limited | Construction | 2003 |
| K&T Briggs Properties Ltd | Real estate | 2019 |
| KA LUN Ling Limited | Hospitality | 2002 |
| Kate Hewitt Limited | Information & communication | 2013 |
| Katonah Ltd | Real estate | 2024 |
| KCW Platinum Cleaning Services Ltd | Administrative & support | 2015 |
| Keekle Meadows Management Company Limited | Households | 2021 |
| KEG and Cask Technologies Limited | Extraterritorial | 2020 |
| Kelly Batty Ltd | Other services | 2010 |
| Keswick Canoe and Bushcraft Ltd | Arts & recreation | 2019 |
| Keswick Holiday Homes Limited | Hospitality | 2004 |
| Kippings & Co Ltd | Real estate | 2025 |
| Kirkbride Joinery & Contractors Limited | Construction | 2006 |
| Kirkby Mech-Eng Design Limited | Administrative & support | 2014 |
| Kirkfell Limited | Real estate | 2018 |
| Kirkgate Arts | Arts & recreation | 2008 |
| KJB Consultancy Cumbria Limited | Public administration | 2018 |
| Kkal Tech Limited | Administrative & support | 2017 |
| Koppers Cocktail Bar Ltd | Hospitality | 2021 |
| Koska Aviation & Consultancy Ltd | Transport & logistics | 2018 |
| Kumite Coach Ltd | Education | 2020 |
| L a Sloan Limited | Financial services | 2023 |
| L G Fell Builders & Plasterers Limited | Construction | 2011 |
| L.E.I Commercial Rentals Ltd | Real estate | 2025 |
| LA Muse Ltd | Professional & scientific | 2024 |
| Lairbeck Properties Ltd | Real estate | 2020 |
| Lake District Activities Ltd | Arts & recreation | 2012 |
| Lake District Barbell Ltd | Wholesale & retail | 2018 |
| Lake District Camper Van Conversions Ltd | Manufacturing | 2017 |
| Lake District Driveways Limited | Administrative & support | 2026 |
| Lake District Livestock Limited | Agriculture & fishing | 2013 |
| Lakeland Capabilities Ltd | Health & social care | 2017 |
| Lakeland Dog Walker Ltd | Other services | 2023 |
| Lakeland Engineering Ltd | Professional & scientific | 2025 |
| Lakeland Food Ltd | Hospitality | 2026 |
| Lakeland Jets Ltd | Construction | 2023 |
| Lakeland Leisure Developments Limited | Construction | 2015 |
| Lakeland Livestock Limited | Agriculture & fishing | 2013 |
| Lakeland Mountain Guides Limited | Administrative & support | 2017 |
| Lakeland Renovations Limited | Construction | 2014 |
| Lakes Edge Brewing Ltd | Manufacturing | 2024 |
| Lakes Electrical Limited | Construction | 2018 |
| Lakes Electrics Ltd | Construction | 2021 |
| Lakes Leisure Limited | Wholesale & retail | 2023 |
| Lakes Premier Property Limited | Administrative & support | 2019 |
| Lakeside Letting Ltd | Hospitality | 2018 |
| Lakesside Ltd | Professional & scientific | 2024 |
| Lapine Lodge Limited | Hospitality | 2025 |
| Laudan Developments Ltd | Construction | 2012 |
| Lawson Properties (Cockermouth) Limited | Real estate | 2015 |
| Lawsons Haulage Limited | Transport & logistics | 1992 |
| LCF VET Ltd | Financial services | 2023 |
| Learning for Life Trust | Education | 2015 |
| LEB105 Limited | Administrative & support | 2019 |
| Lees House Limited | Real estate | 2001 |
| Leesrigg Renewables Limited | Energy | 2014 |
| Leman Services Ltd | Professional & scientific | 2014 |
| LEO Gartland Limited | Construction | 2002 |
| Lewis-Dales and Fells Ltd | Real estate | 2021 |
| Life Safe Passive Fire & Compliance Ltd | Public administration | 2026 |
| Lightburn Technical Solutions Ltd | Professional & scientific | 2007 |
| LIN VET Ltd | Financial services | 2023 |
| Lindsey Thornton Micro-Pigmentation Tattoo Limited | Other services | 2018 |
| Linskeldfield Free Range Eggs Limited | Agriculture & fishing | 2003 |
| Little GEM HR Limited | Professional & scientific | 2014 |
| Livestrong Coaching Ltd | Education | 2025 |
| LJP Commissioning Limited | Administrative & support | 2012 |
| LM Design (Cumbria) Ltd | Administrative & support | 2014 |
| LM Safety & Access Management West Cumbria Limited | Administrative & support | 2024 |
| LMG Treks & Expeditions Limited | Administrative & support | 2019 |
| London Homestay Limited | Hospitality | 1995 |
| Long Close Farm | Agriculture & fishing | 2007 |
| Loopera Systems Ltd | Water & waste | 2026 |
| Loose Joints Limited | Information & communication | 2014 |
| Lorton Lettings Limited | Real estate | 2020 |
| Lorton Road Limited | Households | 2019 |
| Lorton Training Services Limited | Professional & scientific | 2023 |
| Lorton Vale Farms Limited | Agriculture & fishing | 2013 |
| Louise Veterinary Care Limited | Financial services | 2023 |
| LOW Fold Holiday Cottages Ltd | Hospitality | 2023 |
| LOW Hall the Lakes Ltd | Hospitality | 2021 |
| LOW Mill Ranges Cumbria Limited | Wholesale & retail | 2026 |
| LOW Road Close Flats RTM Company Ltd | Households | 2026 |
| LOW Wreah Livestock & Livery Limited | Agriculture & fishing | 2011 |
| Loweswater Informatics Ltd | Information & communication | 2011 |
| Loynd Watson Property Limited | Education | 2015 |
| LPO Information Management Limited | Administrative & support | 2016 |