| Keswick (Cambridgeshire) Ltd | Health & social care | 2017 |
| Kingfisher House (March) Limited | Real estate | 2024 |
| Kingfisher House Lease Co Limited | Real estate | 2024 |
| Kingfisher Orton Ltd | Real estate | 2024 |
| Kingham Audio Visual Ltd | Construction | 2019 |
| KJC 2024 Ltd | Professional & scientific | 2024 |
| KJK Renovations Ltd | Transport & logistics | 2019 |
| Kmec Electrical Services Ltd. | Energy | 2012 |
| Knights END Equestrian Centre LLP | | 2008 |
| Knowles Asset Management Limited | Real estate | 2024 |
| Knowles Logistics Group Limited | Financial services | 2024 |
| Knowles Logistics Limited | Transport & logistics | 1947 |
| Koudijs Animal Nutrition Ltd | Agriculture & fishing | 2010 |
| Kras Logistics Ltd | Transport & logistics | 2025 |
| Kratt Home Improvements Limited | Real estate | 2017 |
| KTG Plumbing and Heating Limited | Construction | 2022 |
| Kuttibaba Ltd | Administrative & support | 2010 |
| L Bevens Associates Ltd | Professional & scientific | 2006 |
| L.H. Group Limited | Professional & scientific | 2000 |
| L.Ogden Carpentry Services Limited | Construction | 2022 |
| LA Motorgroup (March) Ltd | Wholesale & retail | 2018 |
| Laura Creese Limited | Real estate | 2025 |
| Lauren Carter Ltd | Professional & scientific | 2018 |
| Lauren’S Cleaning Co. Ltd | Administrative & support | 2026 |
| Law Fertilisers Holdings Limited | Financial services | 2013 |
| Law Fertilisers Limited | Manufacturing | 1993 |
| LDL (Fenland Developments) Ltd | Construction | 2017 |
| Leader Telecommunication Company Ltd. | Administrative & support | 2003 |
| Leaf Crafts Ltd | Wholesale & retail | 2018 |
| Leaf Storage Ltd | Transport & logistics | 2017 |
| Leeding Estates LLP | | 2018 |
| Leeding Projects Limited | Construction | 2016 |
| Leon Kitchen Bistro Ltd | Hospitality | 2025 |
| Lets Outsource Ltd | Transport & logistics | 2023 |
| Letty Care Limited | Health & social care | 2024 |
| LH Holdings Limited | Professional & scientific | 2002 |
| LH Plumbing Ltd | Construction | 2021 |
| Lingo Learning Ltd | Administrative & support | 2017 |
| Lioncross Whitworth Limited | Construction | 2020 |
| Lisa Poll Properties Limited | Real estate | 2021 |
| Live While You'Re Alive Ltd | Extraterritorial | 2025 |
| LJ Lettings Limited | Real estate | 2025 |
| LJR Construction Ltd | Construction | 2023 |
| LLB Services Ltd | Construction | 2018 |
| LLD Holdings Limited | Real estate | 2023 |
| LMP Services Limited | Extraterritorial | 2025 |
| Logical Landscapes Ltd | Administrative & support | 2026 |
| Lombardo Plumbing & Heating Limited | Construction | 2010 |
| London Nails Bar Ltd | Other services | 2025 |
| Longhill Energy Limited | Energy | 2003 |
| Loukasia Ltd | Professional & scientific | 2023 |
| Lovelyyou Ltd | Wholesale & retail | 2026 |
| Loyal Hearts Home Care Limited | Health & social care | 2025 |
| LS Finance Ltd | Professional & scientific | 2025 |
| LTB Continental Ltd | Transport & logistics | 2014 |
| LTS Consultancy Ltd | Water & waste | 2018 |
| Lumina by Beverley Ltd | Health & social care | 2025 |
| Luxe Home and Gardens Limited | Real estate | 2023 |
| Luxmy Service Station Ltd | Wholesale & retail | 2014 |
| Lynchwood Developments Ltd | Construction | 2021 |
| M & W Ceramics Ltd | Construction | 2012 |
| M J Deighton Building Contractor Limited | Construction | 2006 |
| M Ward Construction Limited | Construction | 2013 |
| M&J Shoesmith Limited | Construction | 2021 |
| M&Jp Transport Ltd | Transport & logistics | 2021 |
| M-Dem Consulting Ltd | Information & communication | 2019 |
| M-E Mobile Carwash Ltd | Administrative & support | 2025 |
| M.C. Kisby Limited | Agriculture & fishing | 1975 |
| M.F.Martin Limited | Agriculture & fishing | 1959 |
| M.J.S. Acquisitions (March) Ltd | Construction | 2017 |
| M.J.S. Construction (March) Limited | Construction | 1995 |
| M.J.S. Developments (March) Limited | Construction | 2010 |
| M.J.S. Holdings (March) Limited | Construction | 2015 |
| M.J.S. Homes (March) Ltd | Construction | 2017 |
| M.J.S. Investments (March) Limited | Real estate | 1998 |
| M.J.S. Projects (March) Ltd. | Construction | 2013 |
| M.J.S. Safety Training Services Limited | Education | 2012 |
| M.J.S. Venture Holdings (March) Ltd | Real estate | 2017 |
| M.V. Young Scaffolding Limited | Construction | 2005 |
| MA March Ltd | Hospitality | 2026 |
| Mace Frames Ltd | Construction | 2019 |
| MAD Concreting Ltd | Construction | 2020 |
| MAD Construction Ltd | Construction | 2019 |
| Magnolia Close Road Management Ltd | Administrative & support | 2020 |
| Mala Group Limited | Real estate | 2026 |
| Malletts (March) Ltd | Wholesale & retail | 2021 |
| Maple Lettings Ltd | Real estate | 2022 |
| March and County Club Limited | Hospitality | 1930 |
| March Auto Care Ltd | Wholesale & retail | 2016 |
| March CFC Limited | Agriculture & fishing | 2001 |
| March Deserts Ltd | Hospitality | 2024 |
| March Express Ltd | Wholesale & retail | 2018 |
| March Foods Limited | Manufacturing | 2009 |
| March Golf Club Limited | Arts & recreation | 1961 |
| March Grocery Ltd | Wholesale & retail | 2022 |
| March Hire Centre Ltd | Administrative & support | 2009 |
| March Indoor Bowls Club Limited | Arts & recreation | 1992 |
| March Metal Recycling Limited | Professional & scientific | 2002 |
| March Physiotherapy Clinic Limited | Health & social care | 2011 |
| March Podiatry Practice Limited | Health & social care | 2004 |