| Jurata Consulting Ltd. | Professional & scientific | 2019 |
| Justin Whitehouse Consulting Ltd | Administrative & support | 2018 |
| JW Property Group Ltd | Real estate | 2023 |
| K D Tank Supplies Limited | Construction | 2002 |
| Katharine House Gallery Limited | Wholesale & retail | 1999 |
| Katharine Paravicini Limited | Other services | 2014 |
| Keith Dennison Thomas Ltd | Professional & scientific | 2015 |
| Kennet Business Systems Limited | Real estate | 1982 |
| Kennet Tyre Services Limited | Wholesale & retail | 1977 |
| Kensho Digital Media Ltd | Professional & scientific | 2023 |
| Kenyon Associates Limited | Information & communication | 2013 |
| Kestrel Travel Consultancy Limited | Administrative & support | 1995 |
| Keyes Holdings Ltd | Information & communication | 2024 |
| KFS Accountants Limited | Professional & scientific | 2010 |
| KH Regeneration & Development Services Ltd. | Professional & scientific | 2016 |
| Khin Studio Ltd | Manufacturing | 2025 |
| Kime Decoration Limited | Construction | 2023 |
| Kime Restoration Limited | Other services | 2023 |
| Kingham Farms Ltd | Agriculture & fishing | 1998 |
| Kite Horizons Ltd | Information & communication | 2019 |
| KJB Procurement Ltd | Professional & scientific | 2017 |
| KNB Developments Ltd | Real estate | 2020 |
| Knight Building Contractors Limited | Construction | 1996 |
| Knighton Mullins Limited | Wholesale & retail | 2015 |
| Knollys Consulting Limited | Professional & scientific | 2011 |
| Korntorring Ltd | Manufacturing | 2022 |
| Kpgr Limited | Other services | 2007 |
| L & H Components Limited | Professional & scientific | 2004 |
| L&L Buy to LET Ltd | Real estate | 2020 |
| Lakeside Motor Company Limited | Wholesale & retail | 1995 |
| Landyr Limited | Professional & scientific | 2023 |
| Langton Digital Ltd | Information & communication | 2025 |
| Larkswood Property Management Limited | Real estate | 2021 |
| Lase Holdings Ltd | Professional & scientific | 2018 |
| Laundry With Love Ltd | Other services | 2020 |
| Lawntender Limited | Administrative & support | 2003 |
| Lawstone Limited | Professional & scientific | 2020 |
| LB Brasserie Limited | Hospitality | 2025 |
| Leep Buildings Limited | Construction | 2016 |
| Legal ED Limited | Information & communication | 2015 |
| Leisure Pursuits Limited | Professional & scientific | 1997 |
| Lettuce Grow CIC | Health & social care | 2025 |
| Levon Biss Photography Limited | Professional & scientific | 2008 |
| Lexington Properties Limited | Real estate | 2004 |
| LGW Designs Ltd | Professional & scientific | 2016 |
| Libanus Press Limited | Information & communication | 1990 |
| Liberty Garden Buildings Ltd | Wholesale & retail | 2016 |
| Liddington & Co Ltd | Financial services | 2022 |
| Lifestyle Options Limited | Real estate | 2010 |
| Light & Land Energy Limited | Construction | 2009 |
| Lily Designs Limited | Construction | 2005 |
| Linkenholt Ltd | Agriculture & fishing | 2007 |
| Lionucis Ltd | Manufacturing | 2019 |
| Little Bedwyn Consulting Limited | Professional & scientific | 2024 |
| Little Orchard Limited | Information & communication | 2025 |
| Littlebridge Properties Limited | Real estate | 2005 |
| Littlecote Lodge Limited | Real estate | 2017 |
| Live Real Ltd | Other services | 2022 |
| Living Solutions (Swindon) Limited | Construction | 2004 |
| LJC Installations Limited | Manufacturing | 2019 |
| LK Matthews Hair and Beauty Ltd | Other services | 2019 |
| LKL Holdings Ltd | Professional & scientific | 2023 |
| LKL Relief Services Limited | Agriculture & fishing | 2006 |
| LKL Services Limited | Agriculture & fishing | 2006 |
| Lnbi Limited | Administrative & support | 2019 |
| LNH Network Ltd | Professional & scientific | 2016 |
| Local Uncovered Limited | Professional & scientific | 2013 |
| Lodwick Associates Limited | Professional & scientific | 2013 |
| Logan Marquetry Limited | Professional & scientific | 2022 |
| Lomax & Thorne Limited | Other services | 2019 |
| Lomax Power Solutions Ltd | Wholesale & retail | 2023 |
| London Road Management Limited | Households | 1984 |
| Longdale Consultancy Limited | Professional & scientific | 2025 |
| Louise Molloy Therapy Limited | Health & social care | 2021 |
| Loukma Limited | Hospitality | 2019 |
| Loveland Associates Limited | Professional & scientific | 2017 |
| LOW Footprint Lamb Ltd | Agriculture & fishing | 2022 |
| Lowenva Farm Office Services Ltd | Professional & scientific | 2012 |
| Loxley Consulting Services Ltd | Information & communication | 2016 |
| LP Nutrition Ltd | Other services | 2020 |
| Ltnbh Ltd | Arts & recreation | 2020 |
| Lucky Imperial Limited | Hospitality | 2021 |
| Lucy Winfield Property Limited | Administrative & support | 2018 |
| Luminara Limited | Extraterritorial | 2012 |
| Lunar Automotive Limited | Manufacturing | 2019 |
| Luxe Living Solutions Limited | Construction | 2021 |
| Luxuryscent Ltd | Wholesale & retail | 2019 |
| Lynix Group Ltd | Wholesale & retail | 2025 |
| Lynton Downs Limited | Agriculture & fishing | 1958 |
| Lysfield Limited | Households | 2003 |
| M & Marlborough Retail Ltd | Wholesale & retail | 2025 |
| M I Horse Transport Ltd | Transport & logistics | 2015 |
| M T S Gardens Limited | Administrative & support | 2021 |
| M.J.Read Limited | Agriculture & fishing | 1941 |
| M.S. Developments Limited | Professional & scientific | 1978 |
| Mackenzie and Campbell House Limited | Professional & scientific | 1987 |
| Mackenzie and Campbell Properties Limited | Real estate | 1989 |
| Main Accounting & Consultancy Ltd | Professional & scientific | 2024 |
| Maintained Solutions Limited | Information & communication | 2003 |
| Major OIL and GAS Consultants Limited | Mining & quarrying | 2006 |