| Jentt Limited | Information & communication | 2013 |
| Jessica MAY Limited | Other services | 2020 |
| Jessica's the Academy Ltd | Education | 2021 |
| JG Barbers Ashby Limited | Other services | 2018 |
| JG INK Limited | Administrative & support | 2024 |
| JLB Consultancy 61 Ltd | Administrative & support | 2023 |
| JLW Financial Services Ltd | Financial services | 2020 |
| JMC Mechanical Limited | Construction | 2025 |
| Jnbe Limited | Households | 2018 |
| John Evans Technical Services Limited | Administrative & support | 2007 |
| John Lloyd Dental Equipment Services Limited | Wholesale & retail | 2000 |
| John Lloyd Holdings Ltd | Financial services | 2023 |
| Johnson Gill Property Lawyers Ltd | Professional & scientific | 2025 |
| Johnson Murkett and Hurst (Computer Services) Limited | Administrative & support | 1987 |
| Johri Surgical Services Limited | Health & social care | 2011 |
| Jonathan Bradbury Architecture Limited | Professional & scientific | 2022 |
| Journeo Fleet Systems Limited | Construction | 1975 |
| Journeo Passenger Systems Limited | Manufacturing | 1989 |
| Journeo PLC | Construction | 1994 |
| JPP Solutions (UK) Limited | Information & communication | 2005 |
| JRE Limited | Manufacturing | 1992 |
| JRE Precision Limited | Manufacturing | 2009 |
| JSD Electrical Installations Limited | Construction | 2013 |
| Jshelmerdine Expert Psychological Assessments Limited | Health & social care | 2023 |
| JSK Actuarial Ltd | Professional & scientific | 2015 |
| JT Fitness Academy Ltd | Other services | 2021 |
| JTD Accountants Limited | Professional & scientific | 2014 |
| Jtlp Ltd | Real estate | 2022 |
| JUST2COOL Limited | Information & communication | 2001 |
| Jwft Ltd | Professional & scientific | 2023 |
| JXM Consulting Ltd | Professional & scientific | 2023 |
| K & a Actuarial Ltd | Financial services | 2015 |
| K E Sharpe Investments Ltd | Real estate | 2021 |
| K E Sharpe Limited | Financial services | 2015 |
| K H Legal Limited | Professional & scientific | 2022 |
| K M Services (Ashby) Ltd | Transport & logistics | 2020 |
| K R Stores Ltd | Wholesale & retail | 2019 |
| Kaizen Management Limited | Professional & scientific | 2023 |
| Kalala Limited | Real estate | 2003 |
| Kallari Consulting Limited | Administrative & support | 2014 |
| Kanari Internet Limited | Wholesale & retail | 2007 |
| Kanban Solutions Ltd | Administrative & support | 2010 |
| Kangaroouk Limited | Extraterritorial | 2014 |
| Karen Clarke Estates Limited | Real estate | 2005 |
| Karen Loomes Dance Academy Ltd | Education | 2025 |
| Kata Crushing and Recycling Finance Limited | Wholesale & retail | 2008 |
| Kaunsil Limited | Information & communication | 2020 |
| Kaunty Healthcare Limited | Health & social care | 2023 |
| KBD Consulting Ltd | Professional & scientific | 2025 |
| Keedwell Construction Limited | Construction | 2007 |
| Keelo Ltd | Construction | 2025 |
| Keen and Co Consulting Ltd | Information & communication | 2023 |
| Keith Mcdonald Limited | Health & social care | 2007 |
| Keltek Ltd | Professional & scientific | 2017 |
| Kelvin Ross Engineering Limited | Manufacturing | 2006 |
| Ken's Customs Ltd | Wholesale & retail | 2014 |
| Kent Pain Clinic Ltd | Health & social care | 2010 |
| Keystone Countryside Solutions Limited | Information & communication | 2024 |
| Keystone Performance Limited | Professional & scientific | 2026 |
| Kilwardby Limited | Professional & scientific | 2013 |
| Kimmitt Tempering Services Ltd | Professional & scientific | 2000 |
| Kind Studio Ashby Ltd | Wholesale & retail | 2025 |
| Kinetik Energy Ltd | Administrative & support | 2018 |
| Kinetikos Solutions Ltd | Professional & scientific | 2025 |
| Kingswood Design (UK) Ltd | Manufacturing | 2011 |
| Kionik Group Ltd | Information & communication | 2026 |
| Kitaeru Consulting Ltd | Professional & scientific | 2025 |
| KJR Private Ltd | Wholesale & retail | 2017 |
| KLT Medical Ltd | Administrative & support | 2017 |
| KM Property Lettings Limited | Real estate | 2025 |
| KMR Brickwork Ltd | Construction | 2025 |
| KMR Homes Ltd | Real estate | 2026 |
| Knights Investment Solutions Limited | Professional & scientific | 2014 |
| Knot Speed Limited | Professional & scientific | 2025 |
| Koala Properties Limited | Real estate | 1996 |
| Konecranes Demag UK Limited | Manufacturing | 1970 |
| Kraken Offshore Ltd | Professional & scientific | 2018 |
| KYA Consultancy Ltd | Professional & scientific | 2023 |
| L & M Software 2000 Limited | Information & communication | 2000 |
| L.U. Property Lettings Ltd | Real estate | 2022 |
| LA Mode Pour LES Ours Limited | Wholesale & retail | 2015 |
| Lackfield Ltd | Wholesale & retail | 2021 |
| Lakeside Logistics Ltd | Transport & logistics | 2003 |
| Lakeside Wills & Financial Services Ltd | Administrative & support | 2015 |
| Lako Logistic Ltd | Transport & logistics | 2012 |
| Lakshmi Vyuha Ltd | Financial services | 2020 |
| Lancashire Electrical Services Ltd. | Construction | 2007 |
| Langridge Consulting Services Limited | Professional & scientific | 2019 |
| Lapis Consultancy Limited | Information & communication | 2017 |
| Larc Construction Ltd | Construction | 2013 |
| Lashes by Nicole FAY Limited | Other services | 2023 |
| Lawrence Automation Limited | Professional & scientific | 2005 |
| Lazway Limited | Professional & scientific | 2006 |
| LC Outside Ltd | Administrative & support | 2018 |
| LCO Energy Ltd | Construction | 2025 |
| Lcrc Properties Ltd | Real estate | 2023 |
| LDS Barratts Properties Ltd | Real estate | 2026 |
| Leading Excellence (UK) Limited | Education | 2016 |
| Lean Business Systems Limited | Other services | 2018 |
| Leantoo Ltd | Professional & scientific | 2022 |