| ITH Building Services Ltd. | Construction | 2004 |
| Itrm Clinic Limited | Health & social care | 2011 |
| ITS Holding & Management Ltd | Other services | 2013 |
| ITS IT Europe Limited | Financial services | 2018 |
| Itttybitty Ltd | Arts & recreation | 2023 |
| ITZ Delhi Limited | Hospitality | 2025 |
| ITZ Gaming Centre Ltd | Wholesale & retail | 2020 |
| Iulian Cazacu Ltd | Transport & logistics | 2022 |
| Iulian HGV Ltd | Transport & logistics | 2025 |
| Iulian Logistics Ltd | Transport & logistics | 2024 |
| Iulian Logistics Services Limited | Transport & logistics | 2018 |
| Iuliana Comnea Ltd | Health & social care | 2016 |
| Iulius Logistic Limited | Transport & logistics | 2015 |
| Ivan and Ivan Ltd | Construction | 2019 |
| Ivanhoe Homes Ltd | Construction | 2017 |
| Ivanweiss.London Limited | Professional & scientific | 2021 |
| Ivee Limited | Hospitality | 2025 |
| Iveemart Limited | Financial services | 2024 |
| Ivoltz Limited | Construction | 2017 |
| Ivory Printers (Holdings) Limited | Information & communication | 2006 |
| IVY Cottage Homeware Limited | Wholesale & retail | 2016 |
| IVY Farm Limited | Real estate | 2015 |
| IVY House Fostering Agency Limited | Health & social care | 2019 |
| IVY Property Lettings Ltd | Real estate | 2024 |
| IVY Trans Ltd | Transport & logistics | 2022 |
| Ivybettybletea Ltd | Transport & logistics | 2023 |
| IWA Ltd | Wholesale & retail | 2025 |
| Iwanyckyj Design Ltd | Information & communication | 2018 |
| IWT Investments Ltd | Real estate | 2021 |
| Iyabs AWE Property Ltd | Real estate | 2023 |
| Iyadd Global Store Ltd | Wholesale & retail | 2025 |
| IZA Ltd | Real estate | 2025 |
| Izaiah Healthcare Recruitment Limited | Public administration | 2023 |
| Izmir Kebab Pizza Limited | Hospitality | 2019 |
| J Brennan Holdings Ltd | Financial services | 2020 |
| J & a Hospitality Limited | Hospitality | 2023 |
| J & B BIO Limited | Water & waste | 2014 |
| J & B Boats Ltd | Administrative & support | 2024 |
| J & B Recycling Limited | Water & waste | 1994 |
| J & E Richards Limited | Construction | 1994 |
| J & H PUB Co Ltd | Hospitality | 2020 |
| J & J Security & Electrical Limited | Construction | 2009 |
| J & J Style Limited | Construction | 2024 |
| J & K Automotive Solutions Ltd | Wholesale & retail | 2024 |
| J & L Properties (Doncaster) Limited | Real estate | 2003 |
| J & M Bedrooms Limited | Manufacturing | 2015 |
| J & M Fireplace Fitters Ltd | Construction | 2012 |
| J & M Services (2010) Limited | Construction | 2010 |
| J & N Food Equipment Limited | Wholesale & retail | 2004 |
| J & P Developments Ltd | Real estate | 2018 |
| J & R Recovery Limited | Wholesale & retail | 2024 |
| J & S Facilities Management Limited | Administrative & support | 2015 |
| J & S Metals 2024 Ltd | Wholesale & retail | 2023 |
| J & S Metals Ltd | Wholesale & retail | 2013 |
| J & V Events Ltd | Hospitality | 2018 |
| J a COX Ltd | Real estate | 2018 |
| J and D Activities Limited | Health & social care | 2013 |
| J Anderson Plumbing Ltd | Construction | 2025 |
| J Anne Developments Ltd | Real estate | 2026 |
| J B Autos UK Ltd | Wholesale & retail | 2009 |
| J B Chafor & SON Limited | Wholesale & retail | 2012 |
| J Brownbridge Ltd | Construction | 2021 |
| J C Dunstan Limited | Professional & scientific | 2019 |
| J C Stevens TM Ltd | Public administration | 2025 |
| J Count Engineering Limited | Extraterritorial | 2018 |
| J D Building & Joinery Services Ltd | Construction | 2015 |
| J Douglas Haulage Limited | Transport & logistics | 2014 |
| J Duckitt & Sons Limited | Agriculture & fishing | 2005 |
| J E Waters Haulage Ltd | Transport & logistics | 2026 |
| J F Grehan Ltd | Extraterritorial | 2024 |
| J F Tomlinson & Co Ltd | Transport & logistics | 2002 |
| J G Roofing Solutions Ltd | Construction | 2023 |
| J J Graham Amusements Limited | Arts & recreation | 2022 |
| J J Plant Ltd | Administrative & support | 2013 |
| J Lambregts Ltd | Other services | 2025 |
| J Lifton TM Ltd | Public administration | 2025 |
| J M Cheetham Rail Ltd | Construction | 2019 |
| J M Construction (Doncaster) Ltd | Construction | 2022 |
| J M Holling Transport Limited | Transport & logistics | 2016 |
| J M Mcgill Properties Limited | Real estate | 2021 |
| J Martin Construction Limited | Administrative & support | 2014 |
| J Morrell & Co Limited | Agriculture & fishing | 2008 |
| J Morris Building Contractors Ltd | Construction | 2020 |
| J Morris Building Ltd | Construction | 2015 |
| J P Autotransport Ltd | Transport & logistics | 2023 |
| J P CNC Services Ltd | Manufacturing | 2017 |
| J P Excavations Ltd | Construction | 2011 |
| J P J Contracts Limited | Manufacturing | 2015 |
| J P Peterson Ltd | Wholesale & retail | 2016 |
| J P Prop Limited | Real estate | 2024 |
| J P Walton & SON (Transport) Limited | Transport & logistics | 2006 |
| J Porter & SON Limited | Wholesale & retail | 2007 |
| J Property Enterprise Limited | Real estate | 2022 |
| J R Claims UK Limited | Other services | 2015 |
| J R Developments (UK) Ltd | Health & social care | 2013 |
| J R G Enterprises Ltd | Other services | 2019 |
| J R Recovery (Yorkshire) Ltd | Transport & logistics | 2026 |
| J Rickell Ltd | Professional & scientific | 2026 |
| J Rust & SON Limited | Construction | 2023 |
| J S Developments (Doncaster) Limited | Professional & scientific | 2017 |