| Isis Estate Management Limited | Professional & scientific | 2004 |
| Iskra Two Ltd | Real estate | 2020 |
| Islam Catering Ltd | Hospitality | 2025 |
| Island Construction York Ltd | Construction | 2023 |
| Islandpay Ltd | Administrative & support | 2025 |
| Isle Valley Vets Limited | Professional & scientific | 2012 |
| Islelark Limited | Professional & scientific | 1985 |
| Ismo Investments Limited | Financial services | 2020 |
| ISO Construction Ltd | Professional & scientific | 2026 |
| ISO in a Day Ltd | Professional & scientific | 2022 |
| Isotoma Limited | Information & communication | 2004 |
| Isotoma Technology Limited | Financial services | 2025 |
| ISP Safety First Ltd | Administrative & support | 2025 |
| Issaquah Properties LLP | | 2010 |
| Issho Homes Ltd | Real estate | 2025 |
| IT Covered Limited | Information & communication | 2024 |
| IT Just Makes Sense for Business Solutions Ltd | Administrative & support | 2019 |
| IT Just Makes Sense for Continuous Development Limited | Other services | 2016 |
| IT Masterclasses Limited | Information & communication | 2014 |
| IT Smart Consultancy Limited | Administrative & support | 2010 |
| IT Sports Limited | Wholesale & retail | 2002 |
| Iteleo Limited | Information & communication | 2005 |
| Itineris Solutions Ltd | Financial services | 2013 |
| Itscm Limited | Information & communication | 2014 |
| Itsowen Ltd | Arts & recreation | 2019 |
| IV Display Limited | Professional & scientific | 2021 |
| Ivelett Ltd | Hospitality | 2022 |
| Iver Green Limited | Construction | 2019 |
| Ivesys Consultancy Services Ltd | Information & communication | 2022 |
| Ivinson Autos Limited | Wholesale & retail | 2011 |
| Ivinson Ltd | Administrative & support | 2024 |
| Ivinsons Autos Trustees Ltd | Financial services | 2024 |
| Ivoni Limited | Information & communication | 2025 |
| IVY Lane Hair and Beauty Limited | Other services | 2026 |
| IVY Properties Harrogate Limited | Real estate | 2020 |
| IWC Professional Limited | Professional & scientific | 2015 |
| Iweb Commercial & Marine Services (UK) Ltd | Agriculture & fishing | 2022 |
| IWZ Ltd | Hospitality | 2026 |
| Iyola Limited | Wholesale & retail | 2017 |
| Izro Ltd | Health & social care | 2023 |
| J & E M Gill & SON Limited | Agriculture & fishing | 2006 |
| J & G Engineering Contractors Limited | Energy | 2010 |
| J & H Wynne Design Ltd | Arts & recreation | 2025 |
| J & J Farm Services Ltd | Agriculture & fishing | 2011 |
| J & J Nellis Properties Ltd | Construction | 2013 |
| J & J Properties (York) Limited | Real estate | 2024 |
| J & K Motors Ltd | Real estate | 2003 |
| J & L Ainsworth Limited | Administrative & support | 2016 |
| J & P Monkton Road Limited | Wholesale & retail | 2012 |
| J & S Properties York Ltd | Real estate | 2024 |
| J & S Winstanley Ltd | Agriculture & fishing | 2017 |
| J - Lash Ltd | Other services | 2020 |
| J a Technical Ltd | Professional & scientific | 2021 |
| J ALI Properties Limited | Real estate | 2023 |
| J Atkinson and SON Ltd | Extraterritorial | 2011 |
| J B Drainage Services Ltd | Administrative & support | 2022 |
| J B Groundworks (York) Limited | Construction | 2012 |
| J Banks Signalling Limited | Professional & scientific | 2005 |
| J Beverley Ltd | Information & communication | 2022 |
| J Bowling & SON Ltd | Agriculture & fishing | 2007 |
| J Bramhill Limited | Hospitality | 2024 |
| J Building UK Ltd | Construction | 2019 |
| J Button Building Contractor Limited | Construction | 2018 |
| J C Maxwell Limited | Education | 2020 |
| J C Turnbull Building Contractor Ltd | Construction | 2005 |
| J D Megginson & SON Ltd | Agriculture & fishing | 2019 |
| J D Plastering Services Limited | Construction | 2006 |
| J D Scaffolding Yorkshire Limited | Manufacturing | 2017 |
| J D Scott Properties Ltd | Real estate | 2026 |
| J E Bell & SON Limited | Agriculture & fishing | 2010 |
| J E Schofield Consultancy Ltd | Education | 2025 |
| J Elgie Gardening Services Limited | Administrative & support | 2013 |
| J F Hopson Limited | Real estate | 1956 |
| J G Waterhouse Limited | Agriculture & fishing | 2021 |
| J G Waudby Limited | Construction | 2021 |
| J Hall Plant Ltd | Administrative & support | 2025 |
| J K Scaffolding York Ltd | Construction | 2024 |
| J L C York Ltd | Construction | 2019 |
| J L Carr Ltd | Professional & scientific | 2011 |
| J Lister Electrical Limited | Construction | 2001 |
| J M Butler Holdings Limited | Real estate | 2002 |
| J M Houseman Ltd | Transport & logistics | 2022 |
| J N Piling Limited | Construction | 2011 |
| J Nellis Farms Ltd | Agriculture & fishing | 2014 |
| J Plumbing Ltd | Construction | 2014 |
| J Pooleman Joinery Ltd | Construction | 2021 |
| J R Firby Ltd | Wholesale & retail | 2002 |
| J R Food Solutions Limited | Manufacturing | 2017 |
| J R Gowthorpe Ltd | Agriculture & fishing | 2020 |
| J R Tomlinson Limited | Health & social care | 1999 |
| J R Walton Limited | Financial services | 2016 |
| J Rennison Properties Limited | Real estate | 2018 |
| J Rennison Tree Contractors Limited | Agriculture & fishing | 2014 |
| J Rewcastle & SON Limited | Agriculture & fishing | 2017 |
| J Robinson Plumbing and Heating Ltd | Construction | 2022 |
| J S Goudie Plumbing Ltd | Construction | 2024 |
| J Skelton Garage Services Ltd | Wholesale & retail | 2005 |
| J Smethurst Holdings Ltd | Financial services | 2018 |
| J T YO1 Ltd | Financial services | 2025 |
| J W Property Acquisitions Limited | Real estate | 2025 |