| Inn Collection (Ripon) Limited | Hospitality | 2020 |
| Inn Collection (Seaburn) Limited | Hospitality | 2019 |
| Inn Collection (ST George) Limited | Extraterritorial | 2021 |
| Inn Collection (Swallow Falls) Limited | Extraterritorial | 2021 |
| Inn Collection (Temperance) Limited | Hospitality | 2020 |
| Inn Collection (Tynemouth Castle) Limited | Hospitality | 2020 |
| Inn Collection (Waterhead) Limited | Extraterritorial | 2021 |
| Inn Collection (Whitby) Limited | Hospitality | 2019 |
| Inn Collection (Wordsworth) Limited | Extraterritorial | 2022 |
| Inn Collection Acquisitionco Limited | Extraterritorial | 2013 |
| Inn Collection Bidco 2 Limited | Financial services | 2021 |
| Inn Collection Bidco Limited | Financial services | 2013 |
| Inn Collection Group Limited | Financial services | 2018 |
| Inn Collection Lakes (Ambleside) Limited | Extraterritorial | 2018 |
| Inn Collection Lakes (Coniston) Limited | Extraterritorial | 2018 |
| Inn Collection Ltd | Extraterritorial | 2008 |
| Inn Collection Management Ltd | Extraterritorial | 2008 |
| Inn Collection Midco Limited | Financial services | 2013 |
| Inn Collection Propco 1 Limited | Extraterritorial | 2024 |
| Inn Collection Topco Limited | Financial services | 2013 |
| Inn Collection Trading Limited | Hospitality | 2007 |
| Inn Hospitality Group Ltd. | Hospitality | 2020 |
| Inner Light Wellbeing CIC | Education | 2023 |
| Innisford Investments Ltd | Real estate | 2019 |
| Innit Studios Ltd | Information & communication | 2022 |
| Innocent Bones Limited | Wholesale & retail | 2022 |
| Innoedge Retail and Services Limited | Wholesale & retail | 2025 |
| Innova Utilities Ltd | Administrative & support | 2026 |
| Innovate Property Improvements Ltd | Construction | 2025 |
| Innovation CIP Limited Partnership | | 2017 |
| Innovation Financial Management Ltd | Financial services | 2002 |
| Innovation GP Limited | Financial services | 2016 |
| Innovatis Solutions Ltd | Wholesale & retail | 2012 |
| Innovative Kitchenware Limited | Wholesale & retail | 2015 |
| Innovnex Limited | Information & communication | 2023 |
| Innovo ITS Limited | Information & communication | 2020 |
| Innstay UK Limited | Administrative & support | 2012 |
| Innterplay Limited | Arts & recreation | 2021 |
| Innvest Leisure (Sheff BO) Limited | Hospitality | 2020 |
| INO Cloud Group Ltd | Information & communication | 2023 |
| Inovica Limited | Information & communication | 1998 |
| Inpach Solutions Limited | Information & communication | 2014 |
| Inperpetuity Limited | Professional & scientific | 2016 |
| Inpress Limited | Information & communication | 2002 |
| Inpsychology Limited | Professional & scientific | 2020 |
| Insaya Ltd | Wholesale & retail | 2020 |
| Insideout Home Design Ltd | Professional & scientific | 2021 |
| Insideronline Ltd | Wholesale & retail | 2025 |
| Insieme (Newcastle) Limited | Hospitality | 2019 |
| Insight Healthcare Ltd. | Financial services | 2022 |
| Insight Management Group Ltd | Professional & scientific | 2025 |
| Insight Operations Ltd | Professional & scientific | 2026 |
| Insight OUT Entertainment Limited | Arts & recreation | 2018 |
| Insight-Solutions.Tech Ltd | Manufacturing | 2025 |
| Insightful EYE Ltd | Health & social care | 2022 |
| Insignia Engineering Ltd | Professional & scientific | 2026 |
| Insijam Ltd | Health & social care | 2020 |
| Insite Eyecare Limited | Health & social care | 2006 |
| Insitu Services Limited | Administrative & support | 2006 |
| Insoledout Ltd | Wholesale & retail | 2025 |
| Inspection Solution Ltd | Construction | 2013 |
| Inspir Learning Ltd | Wholesale & retail | 2024 |
| Inspire International Education Ltd | Education | 2024 |
| Inspire Youth Tyne and Wear Community Interest Company | Health & social care | 2013 |
| Inspired Agency Ltd | Professional & scientific | 2007 |
| Inspired Cctv (NE) Ltd | Administrative & support | 2016 |
| Inspired Construction Interior & Exterior Design Ltd Ltd | Manufacturing | 2025 |
| Inspired Joinery and Carpentry Limited | Manufacturing | 2026 |
| Inspired Outsourcing Limited | Administrative & support | 2012 |
| Inspired Support Ltd | Health & social care | 2012 |
| Instant Heating Ltd | Professional & scientific | 2023 |
| Instapill Private Limited | Financial services | 2019 |
| Instawarm Ltd | Construction | 2019 |
| Instinct Properties Limited | Real estate | 2024 |
| Institute of Amateur Cinematographers Limited(The) | Information & communication | 1932 |
| Instor Marketing Services Limited | Professional & scientific | 1967 |
| Instore Radio Productions Limited | Information & communication | 1999 |
| Instrip Demolition Ltd. | Wholesale & retail | 1996 |
| Intake Intelligence Limited | Professional & scientific | 2026 |
| Intasolve Limited | Extraterritorial | 1989 |
| Integellus Financial Solutions Ltd | Financial services | 2017 |
| Integral Energy UK Group Limited | Professional & scientific | 2012 |
| Integral Energy UK Limited | Professional & scientific | 2010 |
| Integral Financial Services UK Limited | Administrative & support | 2011 |
| Integral Software Solutions Ltd | Information & communication | 2012 |
| Integrate Media Limited | Information & communication | 2009 |
| Integrated Display Systems Limited | Manufacturing | 1980 |
| Integrated Medical Interiors Limited | Manufacturing | 2011 |
| Integrated Utility Services Limited | Construction | 1994 |
| Integrity Group Ltd | Professional & scientific | 2025 |
| Intelercs Ltd | Information & communication | 2024 |
| Intelicore Systems Ltd | Information & communication | 2025 |
| Intellectible UK Limited | Information & communication | 2025 |
| Intelligent Care North East Ltd | Health & social care | 2025 |
| Intelligent Electromagnetics Ltd | Professional & scientific | 2021 |
| Intelligent Healthcare Limited | Health & social care | 2025 |
| Intelligent Media (Worldwide) Limited | Information & communication | 1998 |
| Intelligent One Ltd | Financial services | 2020 |
| Intelligent Services Group Ltd | Professional & scientific | 2012 |
| Intelligenteye Limited | Other services | 2012 |