| IT Serve Global Ltd | Information & communication | 2024 |
| IT Started With a Sloth Ltd | Professional & scientific | 2024 |
| IT Still Runs Limited | Wholesale & retail | 2021 |
| IT Talks Ltd | Information & communication | 2026 |
| IT Textile Consultancy Ltd | Professional & scientific | 2020 |
| IT Workspace Ltd | Professional & scientific | 2016 |
| It's ALL I.T. Ltd | Information & communication | 2019 |
| It's Murder (1999) Limited | Arts & recreation | 2014 |
| It's Only Coffee Ltd | Manufacturing | 2025 |
| It's This OR That Limited | Professional & scientific | 2026 |
| It-Depa Ltd | Manufacturing | 2021 |
| IT247 Group Ltd | Financial services | 2025 |
| Itacads Limited | Information & communication | 2005 |
| Italian Bistro Leeds Ltd | Hospitality | 2026 |
| Italian Pizzeria Style Limited | Hospitality | 2026 |
| Italicatessen UK Limited | Hospitality | 2005 |
| Italy Abroad Network Limited | Wholesale & retail | 2003 |
| Itari Ltd | Information & communication | 2021 |
| Itch Petcare Limited | Wholesale & retail | 2018 |
| Itcontract Ltd | Information & communication | 2015 |
| ITD Properties Ltd | Real estate | 2025 |
| Itel Networks Limited | Wholesale & retail | 2024 |
| Itemdawn Limited | Real estate | 1987 |
| Iteradesign Ltd | Manufacturing | 2023 |
| Iterise Ltd | Information & communication | 2019 |
| Itestit Ltd | Information & communication | 2013 |
| Itexact Limited | Information & communication | 2009 |
| Itgms Limited | Information & communication | 2002 |
| Itgo Ltd | Information & communication | 2019 |
| Ithaca (NE) E&P Limited | Mining & quarrying | 1980 |
| Ithaca (NE) Ukcs Limited | Mining & quarrying | 1997 |
| Ithaca Causeway Limited | Mining & quarrying | 2007 |
| Ithaca Dorset Limited | Mining & quarrying | 1973 |
| Ithaca EF Limited | Mining & quarrying | 1999 |
| Ithaca Energy Developments UK Limited | Administrative & support | 2009 |
| Ithaca Epsilon Limited | Mining & quarrying | 2006 |
| Ithaca Exploration Limited | Mining & quarrying | 2006 |
| Ithaca Gamma Limited | Mining & quarrying | 2006 |
| Ithaca J E&P Limited | Mining & quarrying | 2014 |
| Ithaca MA Limited | Mining & quarrying | 2000 |
| Ithaca OIL and GAS Limited | Mining & quarrying | 1981 |
| Ithaca Petroleum Limited | Mining & quarrying | 2004 |
| Ithaca SP (Holdings) Limited | Administrative & support | 2014 |
| Ithaca SP Bonds PLC | Administrative & support | 2017 |
| Ithaca SP E&P Limited | Mining & quarrying | 1980 |
| Ithaca SP Finance Limited | Administrative & support | 2014 |
| Ithaca SP O&G Limited | Administrative & support | 2015 |
| Ithaca SP UK Limited | Financial services | 1991 |
| Ithaca SPE Limited | Administrative & support | 2014 |
| Ithaca Ukcs Limited | Mining & quarrying | 1971 |
| Ithaca Zeta Limited | Mining & quarrying | 2014 |
| Itil Consultants Ltd | Information & communication | 2018 |
| ITL Electrical Limited | Construction | 2023 |
| Itnels Ltd | Administrative & support | 2016 |
| Itrek Digital Solutions Limited | Information & communication | 2013 |
| Itsallinthedtail Ltd | Administrative & support | 2021 |
| Itsfinished.Com Ltd | Health & social care | 2026 |
| Itslearning UK Limited | Education | 1995 |
| Itsoudé Ltd | Wholesale & retail | 2025 |
| Itte Vinay Plastics Ltd | Health & social care | 2025 |
| ITU ATU Books Ltd. | Information & communication | 2021 |
| Ituti Limited | Information & communication | 2023 |
| Itxpress UK Limited | Manufacturing | 2008 |
| Iulia Oral Care Ltd | Health & social care | 2025 |
| Iulian C&G Limited | Transport & logistics | 2018 |
| Iulian Courier Ltd | Transport & logistics | 2025 |
| Iulian M.T. Transport Ltd | Wholesale & retail | 2020 |
| Iuliancretudelivery Limited | Transport & logistics | 2025 |
| Iusca Education Ltd | Education | 2026 |
| Iusolutions Limited | Professional & scientific | 2005 |
| IV Health & Wellness Ltd | Health & social care | 2021 |
| IV Leeds Ltd | Hospitality | 2026 |
| Ivape HQ Ltd | Wholesale & retail | 2019 |
| Ivape Hyde Park Ltd | Wholesale & retail | 2023 |
| Ivape Lounge Morley Ltd | Wholesale & retail | 2024 |
| Ivape Shop Ltd | Wholesale & retail | 2018 |
| Ivape Zone Ltd | Wholesale & retail | 2021 |
| Ivasiya Care Ltd | Health & social care | 2021 |
| IVE Construction & Engineering Ltd | Construction | 2025 |
| Ivegate Developments Limited | Construction | 2014 |
| Ivegate House Ltd. | Professional & scientific | 2017 |
| Ivegate Investments Limited | Administrative & support | 2024 |
| Ivegate Limited | Construction | 2011 |
| Ivegate Maintenance Limited | Construction | 2023 |
| Ivegate Properties Limited | Real estate | 2021 |
| Ivegate Renewable Energy Limited | Construction | 2019 |
| Ivel Business Consultancy Ltd | Professional & scientific | 2013 |
| Iveridge Health Club Limited | Arts & recreation | 2009 |
| Iverna Court Property Limited | Real estate | 2022 |
| Ives Consulting Ltd | Other services | 2018 |
| Iveson Management Limited | Households | 2016 |
| Ivfmicro Limited | Professional & scientific | 2024 |
| Ivie Analytics Limited | Information & communication | 2022 |
| Ivigo International Limited | Wholesale & retail | 1997 |
| Ivison Trust | Education | 2001 |
| Ivitalise Ltd | Health & social care | 2018 |
| Ivorian Solidarity UK Ltd | Health & social care | 2023 |
| Ivoriee Ltd | Wholesale & retail | 2026 |
| Ivory Aesthetics (Leeds) Limited | Other services | 2021 |
| Ivory Designs Limited | Wholesale & retail | 2005 |