| Knightgrade Limited | Water & waste | 1973 |
| Kotec Property Development Limited | Construction | 2021 |
| Kraken Builders Limited | Construction | 2024 |
| Kraken Development Ltd | Construction | 2026 |
| Krayem Trading Company Ltd | Professional & scientific | 1998 |
| Kudu Automotive Limited | Administrative & support | 2008 |
| Kyuri Sushi Ltd | Hospitality | 2021 |
| LA Hair Lounge Limited | Other services | 2013 |
| Larkhill Financial Limited | Professional & scientific | 2017 |
| Lascelles Medical Ltd | Health & social care | 2020 |
| Lathams Contract Services Limited | Administrative & support | 2007 |
| Laudamus TE Support Limited | Health & social care | 2025 |
| LBN Local Business Networks Ltd | Professional & scientific | 2020 |
| LE Jardin Vert Limited | Administrative & support | 2017 |
| LE ROC Limited | Construction | 2012 |
| Leaf and DIG Limited | Administrative & support | 2022 |
| Leap Property Solutions Limited | Real estate | 2016 |
| Lechlade Motor Co Ltd | Wholesale & retail | 2023 |
| LEE Cooper (Tetbury) Limited | Manufacturing | 2003 |
| Level One Hair Design Limited | Other services | 2011 |
| LG Management Company Limited | Professional & scientific | 2017 |
| LHG FM Limited | Other services | 1995 |
| Lincoln Energy Limited | Professional & scientific | 2011 |
| Linden Property Services Ltd | Real estate | 2008 |
| Linney Consulting Limited | Professional & scientific | 2016 |
| Lion Heart Renovations Ltd | Construction | 2019 |
| Lion Place Holdings Limited | Administrative & support | 2024 |
| Lionhouse Projects Ltd | Real estate | 2017 |
| Lionswan Ltd | Other services | 2023 |
| Little GEM Travel Ltd | Administrative & support | 2025 |
| Little Giant Communications Limited | Professional & scientific | 2019 |
| Littlewood Holdings Limited | Real estate | 2020 |
| Livesmart Building Automation Ltd | Information & communication | 2021 |
| LIZ Bamber-Smith Lifestyle Ltd | Professional & scientific | 2024 |
| LLB Financial Services Ltd | Financial services | 2010 |
| LLV Management Company Ltd | Professional & scientific | 2021 |
| LMH Consultants Ltd | Other services | 2014 |
| Lobe Developments Limited | Construction | 2026 |
| Local Housing Development Limited | Construction | 2010 |
| Local Housing Group Limited | Other services | 2002 |
| Lochshiel Limited | Real estate | 2001 |
| Logical Operations Limited | Real estate | 2013 |
| London Nutrition Doctor Limited | Other services | 2014 |
| Loop Enterprise Ltd | Extraterritorial | 2016 |
| Loose Ends Fabrics Limited | Wholesale & retail | 2007 |
| Lorford's Antiques Limited | Wholesale & retail | 2005 |
| Lotus Property and Construction Ltd | Construction | 2024 |
| Lucid Foreign Exchange Ltd | Financial services | 2021 |
| Ludlow Engineering Limited | Manufacturing | 2018 |
| Luke Sweeting (Bricklaying) Limited | Other services | 2013 |
| M CON Developments Limited | Construction | 2025 |
| M CON Holdings Limited | Construction | 2025 |
| M D Heating Limited | Construction | 2022 |
| M R Purchasing Limited | Wholesale & retail | 2015 |
| M T Floor and Wall Tiling Ltd | Construction | 2019 |
| M-Power Physiotherapy Ltd | Other services | 2023 |
| M.J Harlen Limited | Other services | 2025 |
| Mabie Properties Ltd | Real estate | 2022 |
| Macalister Electronics Limited | Professional & scientific | 2026 |
| Macksmith Media Ltd | Other services | 2022 |
| Macm Trade Ltd. | Transport & logistics | 2019 |
| Mains Kettles Ltd | Wholesale & retail | 2025 |
| Maintenance Butler Limited | Wholesale & retail | 2023 |
| Maple (434) Limited | Households | 2018 |
| Marc Avery Ltd | Professional & scientific | 2014 |
| Mark Pollard Heating Services Limited | Construction | 2007 |
| Marlborough Electrical Contractors Limited | Construction | 1991 |
| Marmalade Sky Consultancy Ltd | Information & communication | 2018 |
| Marship Ltd | Manufacturing | 2010 |
| Martin & Malthouse Ltd | Wholesale & retail | 2020 |
| Martyn Construction Limited | Construction | 2021 |
| Martyn Richardson Farriers Ltd | Agriculture & fishing | 2020 |
| Mastertime Limited | Manufacturing | 1991 |
| Matthew Eatwell Limited | Administrative & support | 2008 |
| Matthew Stevens Building & Landscaping Limited | Construction | 2013 |
| MAX Fisher Films Limited | Professional & scientific | 2016 |
| Maybrays Radiators Limited | Wholesale & retail | 2010 |
| Mayer Construction Limited | Construction | 2012 |
| Mayer Interiors Limited | Extraterritorial | 2016 |
| MB Equine Consultancy Limited | Real estate | 2015 |
| Mccarthy Marland (Recycling) Limited | Water & waste | 2001 |
| Mcgowan Transcriptions Limited | Administrative & support | 2009 |
| Melcourt Industries Limited | Manufacturing | 1983 |
| Mepsted International Limited | Transport & logistics | 2024 |
| MF Vehicles Limited | Wholesale & retail | 2014 |
| MFW Services Limited | Professional & scientific | 2024 |
| Mgrm Trading Limited | Professional & scientific | 2010 |
| Michael G Faulkner & Co Limited | Construction | 2025 |
| Microsolve Limited | Information & communication | 1998 |
| Middlesex Marble Limited | Other services | 2008 |
| Mike Hulme Home Improvements Ltd | Construction | 2009 |
| Milbourne Marsh Ltd | Households | 2018 |
| Miles & Deane Developments Limited | Administrative & support | 2010 |
| Mill Mews Lettings Limited | Real estate | 2026 |
| Minerva Consultancy Services Limited | Professional & scientific | 2024 |
| Mint PA Ltd | Information & communication | 2021 |
| MJP Casing Supplies Limited | Wholesale & retail | 1986 |
| MLD Foods Limited | Wholesale & retail | 2012 |
| Mltt Polo Limited | Agriculture & fishing | 2017 |
| MMD Corporate Ltd | Agriculture & fishing | 2026 |