| Lewis Graham Limited | Other services | 2025 |
| Lewis Lakeside Lettings Limited | Real estate | 2025 |
| Liam Taylor Limited | Manufacturing | 2026 |
| Liberate Properties Limited | Households | 2013 |
| Lido DI MEO Limited | Hospitality | 2017 |
| Lighthouse Business Consultancy Ltd | Administrative & support | 2016 |
| Lighthouse Fertility Ltd | Administrative & support | 2024 |
| Lilly's Holiday Lets Ltd | Hospitality | 2022 |
| Lilly's Landing Limited | Hospitality | 2019 |
| Limelight Classic Productions Limited | Information & communication | 2006 |
| Liminality Ltd | Information & communication | 2025 |
| Linda Mason Education Consultancy Ltd | Professional & scientific | 2022 |
| Lingua Forme Limited | Education | 2010 |
| Links Advisory Ltd | Professional & scientific | 2025 |
| Links Art Gallery C.I.C. | Wholesale & retail | 2010 |
| Linux Internet Ltd | Information & communication | 2022 |
| Lion Engineering Solutions Ltd | Construction | 2026 |
| Lish Playgrounds Limited | Construction | 2020 |
| Little Acorns (NE) Limited | Health & social care | 2016 |
| Little Dene Maintenance Limited | Households | 1968 |
| Little Learners Childcare (N.E.) Ltd | Education | 2014 |
| Little Locks Gosforth Limited | Other services | 2025 |
| Live North Property Investments Limited | Real estate | 2021 |
| LJC Inc Ltd | Professional & scientific | 2022 |
| LJF Ices Ltd | Hospitality | 2025 |
| LK9 Pet Services Ltd | Other services | 2017 |
| LKY Sunz Limited | Manufacturing | 2023 |
| LMA Training & Consultancy Ltd | Professional & scientific | 2024 |
| LMV Home Improvements Ltd | Construction | 2024 |
| LNS Accountants Limited | Professional & scientific | 2002 |
| Locksec Ltd | Administrative & support | 2021 |
| Logan Priya Property Investment Ltd | Real estate | 2025 |
| Long-Short Consulting Limited | Professional & scientific | 2021 |
| Longsands Pro Tiling Ltd | Construction | 2024 |
| Longsands Property Group Ltd | Real estate | 2022 |
| Longsands Property Management Ltd | Real estate | 2022 |
| Looney-Parritt Limited | Professional & scientific | 2015 |
| Losing the Shore Ltd | Information & communication | 2025 |
| Louise Guss Consulting Limited | Professional & scientific | 2015 |
| Love More Tattoo Ltd | Other services | 2023 |
| Loved by Lucy Designs Ltd | Wholesale & retail | 2026 |
| Lovely Homes Kitchens and Bathrooms Ltd | Construction | 2025 |
| Lovely Homes North East Ltd | Real estate | 2021 |
| LOW Carbon Journey Ltd | Professional & scientific | 2016 |
| LR Welding & Fabrication Ltd | Manufacturing | 2021 |
| LRD Ltd | Professional & scientific | 2024 |
| LS Joinery and Construction Limited | Construction | 2024 |
| LSC Cadence Ltd | Professional & scientific | 2021 |
| Ltbr Limited | Professional & scientific | 2010 |
| LTV Rentals Ltd | Transport & logistics | 2026 |
| Lucans Ltd | Construction | 2018 |
| Lucisofia Investment Ltd | Real estate | 2021 |
| Lucky Daisy Tattoo Ltd | Other services | 2025 |
| Ludlow Medical Aesthetics Ltd | Other services | 2021 |
| Luhn Properties Ltd | Real estate | 2025 |
| Luke Residential & Leisure Ltd | Real estate | 2024 |
| Lumley Services Limited | Wholesale & retail | 2022 |
| Luna Rose Accommodation Ltd | Real estate | 2025 |
| Lunasands Development Ltd | Construction | 2026 |
| Lushlink Ltd | Information & communication | 2025 |
| Lynn Bennett Resourcing Ltd | Administrative & support | 2014 |
| Lynn Scope Health Coaching Ltd | Other services | 2020 |
| L’Atelier SIP & Paint Ltd | Hospitality | 2026 |
| M and J Motors NE Ltd | Wholesale & retail | 2025 |
| M D Kemp Properties Ltd | Real estate | 2020 |
| M J P Estates Limited | Professional & scientific | 2013 |
| M L Estates Limited | Real estate | 2006 |
| M. Jowsey Meats Ltd | | 2006 |
| Maan Stores Ltd. | Wholesale & retail | 2012 |
| MAC Smith Limited | Wholesale & retail | 1980 |
| Macrae Medical Services Ltd | Health & social care | 2024 |
| Mactech Energy Group Limited | Financial services | 2014 |
| Mactech Invesco Properties Limited | Construction | 2014 |
| MAD in England Ltd | Other services | 2024 |
| Madden Software Solutions Ltd | Information & communication | 2024 |
| Made Wavy Ltd | Manufacturing | 2025 |
| Made With Insight Ltd | Professional & scientific | 2020 |
| Madi Bakes Ltd | Wholesale & retail | 2019 |
| Maezawa Ltd | Wholesale & retail | 2025 |
| Magicminor Limited | Construction | 1986 |
| Magnetic North Enterprise Ltd | Administrative & support | 2024 |
| Magpie Drilling Limited | Extraterritorial | 2003 |
| Magpie Plastering Ltd | Construction | 2025 |
| Magpie Private Hire Limited | Other services | 2024 |
| Mahboubeh Ltd | Other services | 2020 |
| Mahooganew Limited | Information & communication | 2025 |
| Maines-Beasley Creative Limited | Education | 2021 |
| Maintenance and Repairs by Signature Ltd | Construction | 2019 |
| Maltcoin Limited | Other services | 1984 |
| Maltiron Limited | Other services | 1984 |
| Mann Discount Centre Ltd | Wholesale & retail | 2016 |
| Manor Park (Benton) Management Company Limited | Real estate | 2006 |
| Marc Graham Property Developments Ltd | Construction | 2017 |
| Mardan QS Services Limited | Professional & scientific | 2012 |
| Marina Investments Ltd | Real estate | 2015 |
| Marine AVE Engineering Consultants Limited | Professional & scientific | 2018 |
| Mariner Offshore Ltd | Professional & scientific | 2023 |
| Mark Mccreedy Masonry Ltd | Construction | 2015 |
| Mark Wilson Window Services Ltd | Manufacturing | 2008 |
| Market Pavilion C.I.C. | Hospitality | 2024 |