| I Turek Ltd | Health & social care | 2013 |
| I&B Enterprises Ltd | Professional & scientific | 2024 |
| I&K International Company Limited | Wholesale & retail | 2005 |
| I&S Currie Limited | Hospitality | 2007 |
| I'Ll FIX IT Ltd | Other services | 2014 |
| I-Choose Limited | Wholesale & retail | 2012 |
| I-Deal-Me Ltd | Education | 2025 |
| I.E.D Digwa. Sons Limited | Wholesale & retail | 2017 |
| I.T.C. (NE) Limited | Transport & logistics | 2002 |
| I.T.C. Transport North East Limited | Transport & logistics | 2017 |
| IA Accommodations Limited | Real estate | 2013 |
| IAN Belsham Associates Limited | Professional & scientific | 2003 |
| IAN D Clark Joinery Ltd | Construction | 2023 |
| Iatt One Ltd | Financial services | 2021 |
| Iatt Services LLP | | 2021 |
| Ibahc Limited | Construction | 2018 |
| Ibos Pizza & Grill Takeaway Ltd | Hospitality | 2023 |
| Ican Project Solutions Ltd | Construction | 2005 |
| Ichud Ltd | Education | 2018 |
| Icon Controls Ltd | Construction | 2017 |
| Iconique Living Ltd | Wholesale & retail | 2020 |
| Icus Holdings Limited | Real estate | 2019 |
| Ideal Waste Disposal Ltd | Water & waste | 2018 |
| Idols Rocks Limited | Hospitality | 2013 |
| Iepg Limited | Professional & scientific | 2013 |
| IFT Properties Limited | Real estate | 2018 |
| IGI Management Services Limited | Professional & scientific | 1996 |
| Ihcap Limited | Construction | 2017 |
| Ihsaan UK Exports Ltd | Wholesale & retail | 2025 |
| IJ Inspection Services Limited | Professional & scientific | 2013 |
| Ik-Eco Limited | Water & waste | 2000 |
| Iksela Ltd | Information & communication | 2019 |
| IL Grande Ltd | Hospitality | 2025 |
| Illustration Within Design Ltd | Professional & scientific | 2025 |
| IM Energy Solutions(Uk) Limited | Administrative & support | 2026 |
| Immigration Help Services Ltd | Professional & scientific | 2026 |
| Immunogen International Limited | Professional & scientific | 1975 |
| Impact Bathrooms NE Limited | Wholesale & retail | 2014 |
| Impact BRC Ltd | Construction | 2013 |
| Impact Property Services (NE) Limited | Construction | 2025 |
| Imperial Restaurant Ltd | Hospitality | 2019 |
| Imperium Star Group Limited | Real estate | 2018 |
| Import Specialist Ltd | Wholesale & retail | 2021 |
| IMYH18 Ltd | Real estate | 2024 |
| IN Form Design Services Limited | Other services | 2005 |
| IN Genius Holdings Limited | Professional & scientific | 2005 |
| IN Genius Limited | Professional & scientific | 1994 |
| IN House Property Alterations Ltd | Extraterritorial | 2022 |
| IN Service Limited | Real estate | 2001 |
| IN Touch Locum and Design Ltd | Other services | 2017 |
| In-Corporate Development Limited | Other services | 2005 |
| In-Situ Solutions Limited | Professional & scientific | 2025 |
| Inam Property Investment Ltd | Real estate | 2023 |
| Inam Psychiatry Ltd | Health & social care | 2015 |
| Inbound Sales Content Limited | Professional & scientific | 2013 |
| Inclusive Support Services Ltd | Health & social care | 2022 |
| Increase Computers Limited | Information & communication | 1982 |
| Independent Air Treatment Technology Limited | Manufacturing | 2010 |
| Independent Restaurant Group Limited | Hospitality | 2017 |
| Indi Support Ltd | Information & communication | 2025 |
| Indianna Electrical Ltd | Construction | 2019 |
| Indrazlash Ltd | Other services | 2024 |
| Industria Resources U.K. Limited | Energy | 2017 |
| Industrial Landscapes Limited | Other services | 2006 |
| Inex Micro Limited | Manufacturing | 2025 |
| Inex Microtechnology Limited | Manufacturing | 2012 |
| Infinite Frontiers Ltd | Professional & scientific | 2026 |
| Infinite Glow Services Ltd | Health & social care | 2020 |
| Infinity UK Holdings Ltd | Financial services | 2025 |
| Infinity UK Property Holdings Ltd | Real estate | 2025 |
| Infoanyware Limited | Information & communication | 2004 |
| Infra Serve International Ltd | Construction | 2025 |
| Infra Serve Properties Ltd | Real estate | 2025 |
| Infragate Solutions Ltd | Wholesale & retail | 2023 |
| Infrastructure Association Limited | Other services | 2020 |
| Ingenious Circus Transport Limited | Extraterritorial | 2010 |
| Ingham Estates Limited | Real estate | 2023 |
| INK & Drop Ltd | Wholesale & retail | 2018 |
| INK ME UP Tattoo & Piercing Limited | Other services | 2023 |
| Innovation Business Solution Limited | Other services | 2017 |
| Inopro Services Ltd | Construction | 2022 |
| Insane Competitions Ltd | Administrative & support | 2025 |
| Inshealth Limited | Health & social care | 2012 |
| Inside Insulations Limited | Construction | 2025 |
| Insight EDU Ltd | Education | 2025 |
| Insignia NE Ltd | Professional & scientific | 2020 |
| Insink Plumbing Limited | Construction | 2022 |
| Inspira Bathrooms Limited | Wholesale & retail | 2019 |
| Inspire Business Technology Limited | Information & communication | 2008 |
| Inspire Compliance Limited | Professional & scientific | 2002 |
| Inspire Financial Management Limited | Professional & scientific | 2014 |
| Inspire Physiotherapy Ltd | Health & social care | 2022 |
| Inspire Waste Management Ltd | Water & waste | 2016 |
| Inspire Your Business (Number 2) Limited | Professional & scientific | 2021 |
| Inspire Your Business Limited | Professional & scientific | 2001 |
| Inspired Installations NE Ltd | Construction | 2022 |
| Instinct Financial Solutions Limited | Financial services | 2015 |
| Intech AI Limited | Professional & scientific | 2019 |
| Integration Station CIC | Real estate | 2019 |
| Integrity Critical Fire Solutions Ltd | Construction | 2022 |