| IK Management Ltd | Wholesale & retail | 2026 |
| IK Property and Lettings Ltd | Real estate | 2024 |
| Ikon Installation Ltd | Construction | 2024 |
| IKQ Properties Ltd | Real estate | 2023 |
| IL Mulino's Pizza Ltd | Hospitality | 2026 |
| Ilabs Ltd | Information & communication | 2022 |
| Ilachi Limited | Health & social care | 2024 |
| Ileather Ltd | Wholesale & retail | 2016 |
| Illuminate Solutions Ltd | Other services | 2020 |
| Illusion Leads Limited | Manufacturing | 2019 |
| Illustrated Solutions Ltd | Manufacturing | 2020 |
| ILM Training Limited | Other services | 2024 |
| Ilmb Consulting Ltd | Administrative & support | 2014 |
| ILS Automotive Ltd | Wholesale & retail | 2024 |
| Ilume Ltd | Wholesale & retail | 2019 |
| Ilus International UK Ltd | Manufacturing | 2021 |
| IM Green Care Limited | Agriculture & fishing | 2026 |
| Imac NE Ltd | Financial services | 2011 |
| Imagine Digital Arts Ltd | Information & communication | 2015 |
| Iman Gadzhi Consultants Ltd | Professional & scientific | 2025 |
| Imantec Limited | Information & communication | 2009 |
| IMB Properties Ltd | Real estate | 2024 |
| Imfrosty Limited | Real estate | 2025 |
| IMH Workforce Services Ltd | Administrative & support | 2025 |
| Impact Express Limited | Manufacturing | 2004 |
| Impelling Ltd | Information & communication | 2015 |
| Impelling Managed Services Ltd | Information & communication | 2023 |
| Impelling Solutions Ltd | Information & communication | 2009 |
| Imperial Bidco Limited | Professional & scientific | 2019 |
| Imperial Catering Services Limited | Hospitality | 2020 |
| Imperial Oldco Limited | Professional & scientific | 1998 |
| Imperial Performance Limited | Manufacturing | 2014 |
| Imperial Topco Limited | Professional & scientific | 2019 |
| Impetus Clinical Limited | Information & communication | 2024 |
| IMV Properties 28 Limited | Real estate | 2023 |
| IN House Solutions Limited | Professional & scientific | 2018 |
| IN Property Services Limited | Real estate | 2024 |
| In-Tend Asset Management Limited | Professional & scientific | 2006 |
| In-Tend Limited | Information & communication | 2006 |
| IN2AI Ltd | Information & communication | 2025 |
| Inante Ltd | Information & communication | 2017 |
| Inayah Pharmas Limited | Other services | 2015 |
| Incident Aftercare Limited | Other services | 2016 |
| Inclusive Learning Narratives CIC | Professional & scientific | 2026 |
| Independence for Life (Services) Ltd | Administrative & support | 2013 |
| Independence for Life Limited | Health & social care | 2009 |
| Independence Group Ltd | Financial services | 2019 |
| Independent Building Plastics Limited | Wholesale & retail | 2017 |
| Independent Cars Limited | Wholesale & retail | 2004 |
| Independent Fishing Tackle & Bait Shop Limited | Real estate | 2020 |
| Independent Trading Limited | Wholesale & retail | 2011 |
| Independent Vehicle Inspection Services Ltd | Professional & scientific | 2020 |
| India Rose Luxury Hair and Beauty Limited | Other services | 2015 |
| Indian Harvest Limited | Hospitality | 2021 |
| Indigo UK Trading Ltd | Water & waste | 2020 |
| Indulge JP Ltd | Other services | 2023 |
| Indus Global Trading Ltd | Wholesale & retail | 2021 |
| Industrial Battery and Charger Services Limited | Manufacturing | 2000 |
| Industrial Compensation Claims Limited | Professional & scientific | 2006 |
| Industrial Pumps Limited | Manufacturing | 2002 |
| Industrial Software Limited | Information & communication | 2001 |
| Inferno International Transport Ltd | Other services | 2018 |
| Infinite Influence Ltd | Professional & scientific | 2017 |
| Infinite Properties Ltd | Construction | 2013 |
| Infinity Logistic Sales Ltd | Wholesale & retail | 2023 |
| Infivo Ltd | Information & communication | 2025 |
| Infra Wind Ltd | Transport & logistics | 2024 |
| Infyzen Limited | Information & communication | 2025 |
| Ingatestone Investments Ltd | Real estate | 2026 |
| Inge Investments Ltd | Real estate | 2024 |
| Ingeni Property Services Limited | Construction | 2016 |
| Ingleby Lodge Ltd | Administrative & support | 2011 |
| Ingoodshape Limited | Financial services | 2021 |
| Inheat LP | | 2008 |
| Inicio Success Ltd | Administrative & support | 2025 |
| Initburgers and Curry's Ltd | Hospitality | 2026 |
| Injection Alloys Global Limited | Manufacturing | 2000 |
| Injection Alloys Limited | Manufacturing | 1989 |
| Inkfinity Prints Ltd | Manufacturing | 2024 |
| Inkydinky Equine’S Ltd | Agriculture & fishing | 2025 |
| Inline Installations Limited | Construction | 2014 |
| Inn Time Ltd | Hospitality | 2025 |
| Inno Emenu Ltd | Information & communication | 2014 |
| Innoceramics Ltd | Administrative & support | 2016 |
| Innominate HDG Ltd | Transport & logistics | 2026 |
| Innoval Technology Limited | Professional & scientific | 2002 |
| Innovation Recycling and Recovery Ltd | Manufacturing | 2014 |
| Innovation Waste Services Ltd | Water & waste | 2025 |
| Innovation Ways Cleaning Services Ltd | Transport & logistics | 2025 |
| Inoleo Limited | Financial services | 2024 |
| Inserter Sales and Service Limited | Manufacturing | 2012 |
| Insight Plumbing Solutions Ltd | Construction | 2025 |
| Insight Sales Consultancy Limited | Professional & scientific | 2018 |
| INSIGHT4LIVIN Group Limited | Education | 2019 |
| Insightengine Ltd | Information & communication | 2025 |
| Insignia Property Ltd | Real estate | 2023 |
| Insignia Stays Ltd | Real estate | 2025 |
| Insite Life Skills Ltd | Education | 2024 |
| Insite Onsite Limited | Administrative & support | 2012 |
| Inspec NDE Limited | Administrative & support | 2016 |