| J&C Recovery Ltd | Transport & logistics | 2024 |
| Jagland UK Limited | Wholesale & retail | 2011 |
| Jche Consultancy Limited | Professional & scientific | 2022 |
| JK Rail Comms Ltd | Information & communication | 2025 |
| John White (Northampton) Limited | Wholesale & retail | 1998 |
| JPM63 Limited | Administrative & support | 2007 |
| Kabo Creative Limited | Professional & scientific | 2017 |
| Kayleigh Flattery Ltd | Professional & scientific | 2012 |
| Keith Brace Wealth Management Ltd | Professional & scientific | 2010 |
| Kepa Services Ltd | Administrative & support | 2016 |
| KJ Management Limited | Construction | 2005 |
| KJF Recruitment Ltd | Administrative & support | 2022 |
| KM Carpentry Contractors Holdings Ltd | Financial services | 2019 |
| KM Carpentry Contractors Ltd | Construction | 2018 |
| KS Braich Holdings Ltd | Real estate | 2025 |
| Kubala Property Management Ltd | Real estate | 2018 |
| Kully Enterprises Limited | Administrative & support | 2018 |
| Legal Micro Systems Limited | Professional & scientific | 1988 |
| Leicester Future Tech. Consulting Co. Ltd | Professional & scientific | 2019 |
| Level Best Ltd | Construction | 2016 |
| Linrey Construction Ltd | Administrative & support | 2014 |
| Little Steps (Higham Ferrers) Ltd | Health & social care | 2008 |
| Lockwood Case Management Limited | Administrative & support | 2017 |
| LR Environmental Services Limited | Water & waste | 2025 |
| M J F Crane Services Ltd | Construction | 2019 |
| Macannex Consultancy Ltd | Administrative & support | 2008 |
| Machinery Maintenance & Repairs Ltd | Manufacturing | 2009 |
| Make Retail Limited | Wholesale & retail | 2013 |
| Mambo Investments Limited | Real estate | 2018 |
| Mambo Media Limited | Information & communication | 2007 |
| Mana Resourcing Ltd | Administrative & support | 2006 |
| Manor Yard Consultants Ltd | Professional & scientific | 2011 |
| Mark Rumary Sales Solutions Ltd | Wholesale & retail | 2015 |
| Market Square Veterinary Clinic Limited | Real estate | 2003 |
| Matt Bolton Courier Services Limited | Transport & logistics | 2014 |
| Maximise My Business Ltd | Hospitality | 2017 |
| MC Heating Services Ltd | Construction | 2016 |
| Medicine UK Limited | Administrative & support | 2007 |
| Mercury Designed Developments Limited | Construction | 2015 |
| Millfarm NK Limited | Agriculture & fishing | 2020 |
| MJH Haulage Limited | Transport & logistics | 2002 |
| MK Nationwide Couriers Ltd | Transport & logistics | 2024 |
| Moeraki Developments Limited | Professional & scientific | 2013 |
| Moto Rosso Limited | Extraterritorial | 2008 |
| N a Green Limited | Construction | 2004 |
| Necchi (England) Ltd | Wholesale & retail | 2025 |
| NGM Services Limited | Administrative & support | 2004 |
| Nivaal Resources Ltd | Wholesale & retail | 2024 |
| Northamptonshire Parent Carer Voices CIC | Information & communication | 2024 |
| NS Investment Group Ltd | Financial services | 2022 |
| Omega CAD Limited | Professional & scientific | 2015 |
| Partyard Ltd | Administrative & support | 2013 |
| Paul Summers Surveyors Limited | Professional & scientific | 2022 |
| Pauvanant Ltd | Administrative & support | 2011 |
| PEN and INK Book Company Limited(The) | Information & communication | 1983 |
| Pernitech Limited | Professional & scientific | 2010 |
| PFS Parts Ltd | Wholesale & retail | 2003 |
| Poots Ltd | Administrative & support | 2017 |
| Primrose Landscapes (UK) Limited | Other services | 2008 |
| PTP Limited | Administrative & support | 1990 |
| QAS Mechanical Limited | Construction | 2003 |
| R M Masonary Ltd | Construction | 2016 |
| R.G.D. Building Services Limited | Construction | 2002 |
| R.J. Turner Haulage Limited | Transport & logistics | 2003 |
| Raunds Child Centre | Education | 2005 |
| Real Composite Solutions Ltd | Administrative & support | 2016 |
| Red Brick Education Limited | Administrative & support | 2016 |
| Redwood Management (UK) Limited | Real estate | 2005 |
| Richard North MAC Tools Ltd | Wholesale & retail | 2018 |
| RLK Engineering Design Ltd | Administrative & support | 2023 |
| Rocom Performances Limited | Extraterritorial | 1987 |
| Rolton Acquisitions Limited | Professional & scientific | 2024 |
| Rolton Holdings Limited | Professional & scientific | 2012 |
| Roy's Minibuses Ltd | Transport & logistics | 2011 |
| RSI Consulting Limited | Information & communication | 2007 |
| Rusham Ltd | Professional & scientific | 2012 |
| Rutland Plant and Grab Hire Ltd | Administrative & support | 2019 |
| S Hughes Building Services Limited | Construction | 2010 |
| S.Green Electrical Ltd | Construction | 2019 |
| Saffron Residents Management Limited | Households | 2014 |
| SD & MJ Property Ltd | Real estate | 2025 |
| Sedis Company Limited | Wholesale & retail | 1970 |
| Sereniteecare Ltd | Health & social care | 2019 |
| Seven Hills International Limited | Administrative & support | 2006 |
| Shelele Professional Services Ltd | Health & social care | 2015 |
| Shell Brickwork Ltd | Administrative & support | 2011 |
| Sheval Shoes Limited | Wholesale & retail | 2000 |
| SIX MJ (Property) Limited | Real estate | 2020 |
| SIX MJ (Rentals) Ltd | Real estate | 2021 |
| SIX MJ Limited | Professional & scientific | 2014 |
| Smart Paint Solutions Limited | Wholesale & retail | 2016 |
| Software Associates International Ltd | Information & communication | 2022 |
| SRS Group Holdings Ltd | Administrative & support | 2016 |
| Stagecraft Media Group Limited | Administrative & support | 2004 |
| Stanley Roofing Services Ltd | Construction | 2021 |
| Steadfast Trading Limited | Wholesale & retail | 2011 |
| Sunset Healthcare Limited | Health & social care | 2021 |
| Synopta Limited | Information & communication | 2007 |
| System Seals Europe Ltd | Wholesale & retail | 2010 |
| Talent Broker Business Services Ltd | Administrative & support | 2012 |