| Integrity Compass Ltd | Administrative & support | 2019 |
| Inverted EV Ltd | Manufacturing | 2021 |
| IPI Global Solutions Digital Ltd | Information & communication | 2025 |
| IRB Properties Ltd | Construction | 2025 |
| Irons Lions House Ltd | Wholesale & retail | 2023 |
| ISE Consulting Limited | Professional & scientific | 2026 |
| IT & a Contracting Ltd | Information & communication | 2016 |
| Itadvocate Ltd | Information & communication | 2020 |
| Ivatts Art Ltd | Wholesale & retail | 2021 |
| J & B Paddock Management Company Limited | Real estate | 2015 |
| J & D Creasey Limited | Agriculture & fishing | 2008 |
| J & M Contractors (Holbeck) Limited | Administrative & support | 2006 |
| J and S Farm Partnership Ltd | Wholesale & retail | 2025 |
| J C Engineering (Precision) Limited | Manufacturing | 2002 |
| J D Ward Family Investment Co Limited | Financial services | 2024 |
| J Keywood Sportsturf Ltd | Administrative & support | 2020 |
| J Smith Financial Services Ltd | Financial services | 2019 |
| J&E Young Property Limited | Real estate | 2025 |
| J. Laverack Bicycles Ltd | Manufacturing | 2015 |
| J.A.B Catering Limited | Hospitality | 2023 |
| J.E. Wood & Sons (Farmers) Limited | Agriculture & fishing | 1967 |
| Jackson Global Construction Ltd | Administrative & support | 2024 |
| Jallen Holdings Limited | Financial services | 2026 |
| James & James Financial Advisers Limited | Financial services | 2010 |
| James Salon & Barber Ltd | Other services | 2020 |
| James Sellicks Oakham Limited | Real estate | 2014 |
| James Truscott Consulting Ltd | Professional & scientific | 2023 |
| Jaryah Limited | Professional & scientific | 2020 |
| JAY Bloodstock Ltd | Agriculture & fishing | 2024 |
| JBT Strategy Ltd | Professional & scientific | 2019 |
| Jdel Garrison Investments Limited | Professional & scientific | 2014 |
| Jess Bowen Photography Limited | Professional & scientific | 2025 |
| Jfab Fabrication Limited | Manufacturing | 2025 |
| JH Express Ltd | Wholesale & retail | 2024 |
| JHS Events Ltd | Arts & recreation | 2012 |
| JHS Property Maintenance Ltd | Construction | 2026 |
| Jigsaw Asset Management Limited | Real estate | 2019 |
| Jigsaw Capital Management Limited | Real estate | 2024 |
| Jigsaw of Life (Vocational Development) UK LLP | | 2013 |
| Jigsaw of Life Limited | Education | 2007 |
| JJ Browett Advisory Limited | Other services | 2015 |
| Jmjw Ltd | Professional & scientific | 2024 |
| JNG Project Services Ltd | Information & communication | 2024 |
| Jnmd Lettings Limited | Real estate | 2018 |
| John Sheehan Consulting Limited | Professional & scientific | 2008 |
| John Turner and SON Limited | Agriculture & fishing | 2025 |
| Jollys Toys Limited | Wholesale & retail | 2016 |
| Joseph Dejardin Ltd | Professional & scientific | 2017 |
| Joshnina Consulting Limited | Professional & scientific | 2015 |
| Jubilee Property Company (Northants) Limited | Real estate | 2010 |
| Judestone Properties Limited | Real estate | 2021 |
| Junes Farm Limited | Agriculture & fishing | 2024 |
| Just Driver Training Limited | Education | 2016 |
| Just Driving Instructor Training Limited | Education | 2025 |
| JWS Carpentry & Joinery Ltd | Construction | 2026 |
| JYD NET Zero Ltd | Information & communication | 2023 |
| K & J Services (Cottesmore) Ltd | Professional & scientific | 2010 |
| K & S Developments (Langham) Limited | Construction | 2007 |
| Kaimai Ltd | Information & communication | 2017 |
| Kama Advisory Ltd | Professional & scientific | 2023 |
| Kantan Solutions Ltd | Professional & scientific | 2018 |
| Katherine Senior Associates Limited | Information & communication | 2002 |
| Katie Cardew Illustrations Ltd | Wholesale & retail | 2017 |
| Katie Carey Media Ltd | Professional & scientific | 2021 |
| Kavanagh's Tea Room Limited | Hospitality | 2016 |
| Kaybee Developments Limited | Construction | 2017 |
| Kconsultancy(Rutland) Limited | Professional & scientific | 2018 |
| Keep Rutland and Melton Rural Ltd | Other services | 2024 |
| Keepsake Balloon Art Ltd | Wholesale & retail | 2018 |
| Keighwood Limited | Professional & scientific | 1987 |
| Keira Harris Motorsport Ltd | Real estate | 2026 |
| Kemography Diagnostics Ltd | Health & social care | 2024 |
| Kenlock Ltd. | Professional & scientific | 2015 |
| Kerbl UK Limited | Wholesale & retail | 2019 |
| Kerridge Place Management Company Limited | Administrative & support | 2003 |
| Kevin O'Brien GAS Services Limited | Construction | 2019 |
| Kevin Thorpe Medical Cover Ltd | Health & social care | 2019 |
| Keystone Property and Consultancy Ltd | Professional & scientific | 2024 |
| Keystroke Medical Limited | Administrative & support | 2026 |
| Khaki Developments Limited | Construction | 2018 |
| KI Agency Limited | Other services | 2011 |
| Kibworth Antique Centre Limited | Wholesale & retail | 2012 |
| Kinetix Data Solutions Limited | Information & communication | 2017 |
| Kirks Close Residents Group Limited | Extraterritorial | 2010 |
| Kirkstone Planning & Regeneration Ltd | Professional & scientific | 2021 |
| Kirsteingeophysical Ltd | Professional & scientific | 2017 |
| Kiss ME by Isabelle Ltd | Wholesale & retail | 2025 |
| Kiya Design Limited | Wholesale & retail | 2016 |
| Kmatrix Data Services Limited | Information & communication | 2012 |
| Kmatrix Limited | Information & communication | 2007 |
| Knotting Hill Farmhouse Limited | Construction | 2021 |
| Knotting Hill II Ltd | Construction | 2022 |
| Kohinoor Trading Ltd | Wholesale & retail | 2026 |
| Komorebi Medical Limited | Extraterritorial | 2020 |
| Komotion Expeditions Ltd | Transport & logistics | 2022 |
| Kouwi Sport Active CIC | Administrative & support | 2026 |
| Kouwi Sport Limited | Manufacturing | 2025 |
| KPG Digital Ltd | Manufacturing | 2021 |
| Kraftiko Ltd | Wholesale & retail | 2014 |
| KS Groundworks and Landscaping Ltd | Extraterritorial | 2025 |