| Imperial Kerala Ltd | Hospitality | 2017 |
| Imperial Lotus Limited | Wholesale & retail | 2015 |
| Imperium Gate Management Company Limited | Households | 2013 |
| Imperius Holdings Limited | Financial services | 2024 |
| IMT Digital Marketing Ltd | Professional & scientific | 2025 |
| IN the Nutshell Ltd | Wholesale & retail | 2021 |
| IN Trade Compliance Ltd | Professional & scientific | 2024 |
| In-Excess UK Limited | Wholesale & retail | 2003 |
| Inair Ltd | Wholesale & retail | 2020 |
| Incipio Holdings Ltd | Real estate | 2025 |
| Inclusive Growth Ltd | Professional & scientific | 2022 |
| INCUBE8 Ltd | Professional & scientific | 2020 |
| Independent Living Solutions Limited | Health & social care | 2000 |
| Independent Practice Services Limited | Health & social care | 2013 |
| Independently Blue Ltd | Information & communication | 2014 |
| Indie Games Services Ltd | Information & communication | 2012 |
| Indigo 102 Limited | Information & communication | 2007 |
| Indigo Landscape Architects Limited | Professional & scientific | 2000 |
| Indulge Catering Limited | Hospitality | 2013 |
| Industrial Test Systems Europe Limited | Professional & scientific | 2005 |
| Infinite Design Consulting Limited | Professional & scientific | 2024 |
| Inflatable Dreams Ltd | Administrative & support | 2025 |
| Infonautix Consulting Limited | Information & communication | 2016 |
| Information Technology Support Salisbury Ltd | Other services | 2011 |
| Ingenic Developments (Trowbridge) Limited | Construction | 1997 |
| Ingenic Developments Limited | Real estate | 2007 |
| Inglewood (Whittingham) Management Company Limited | Households | 2022 |
| Inglis Physiotherapy Ltd | Health & social care | 2021 |
| Inguni Ltd | Health & social care | 2022 |
| INK Technical Services Limited | Construction | 2015 |
| Inkspace Limited | Professional & scientific | 2017 |
| Inn Gear Limited | Manufacturing | 1985 |
| Innauraa Ltd | Wholesale & retail | 2025 |
| Innotec Supplies (UK) Limited | Other services | 1997 |
| INNOV8 Displays Ltd | Administrative & support | 2018 |
| INNOV8 Fitness & Rehab Ltd | Arts & recreation | 2014 |
| Innovate Make Ltd | Manufacturing | 2021 |
| Innovate Product Design Ltd | Professional & scientific | 2009 |
| Innovation Advisory Ltd | Professional & scientific | 2025 |
| Innuendo (BAT & Ball) Limited | Hospitality | 2011 |
| Inroad Media Limited | Information & communication | 2013 |
| Insect Alert Systems CIC | Professional & scientific | 2026 |
| Insiteability Limited | Information & communication | 2004 |
| Inspiration Hub Property Ltd | Real estate | 2018 |
| Inspire Energy Limited | Construction | 2026 |
| Inspire Exhibitions Limited | Administrative & support | 2015 |
| Inspire Family Solicitors & Mediators Limited | Professional & scientific | 2011 |
| Inspire Home & Business Group Ltd | Administrative & support | 2014 |
| Inspire Mobility Limited | Wholesale & retail | 2007 |
| Inspire Orthodontics Ltd | Health & social care | 2017 |
| Inspire Video Games Ltd | Wholesale & retail | 2020 |
| Inspire-Assessments Ltd | Education | 2022 |
| Inspired Installations Southern Ltd | Construction | 2013 |
| Inspired Property Management Limited | Households | 2014 |
| Inspired Resourcing Limited | Administrative & support | 2012 |
| Insurance Development and Training Limited | Financial services | 1999 |
| Insurance Support Solutions Ltd | Administrative & support | 2019 |
| INT Trade Law Limited | Professional & scientific | 2020 |
| Intbox Solutions Limited | Information & communication | 2013 |
| Intco Confectionery Limited | Wholesale & retail | 2025 |
| Integra Solutions Limited | Wholesale & retail | 2021 |
| Integral Resources Limited | Administrative & support | 2012 |
| Integrated & Vertically Aligned Solutions Ltd | Professional & scientific | 2018 |
| Integriclad Consultancy Limited | Other services | 2024 |
| Integriclad Consultants Limited | Other services | 2024 |
| Intelli Light UK Limited | Arts & recreation | 2006 |
| Intelligent Eyes Security Limited | Administrative & support | 2022 |
| Intelligent Green Projects Limited | Professional & scientific | 2014 |
| Intelligent Outcomes Limited | Professional & scientific | 2021 |
| Intelligent Systems (Southern) Limited | Construction | 2007 |
| Intentions Aromatherapy UK Ltd | Manufacturing | 2026 |
| Inter-Services Research Bureau Ltd | Professional & scientific | 2018 |
| Interbuys Group Limited | Information & communication | 2019 |
| Interconnective Limited | Administrative & support | 2000 |
| Interim Sales Limited | Information & communication | 2006 |
| Intermedia Communication Solutions Ltd | Information & communication | 2003 |
| International Cat Care | Education | 2006 |
| International Cat Care (Enterprises) Limited | Wholesale & retail | 2020 |
| International Healing Animals Consultancy and Services Ltd | Other services | 2022 |
| Interparcos U.K. Limited | Wholesale & retail | 2009 |
| Into the Green Publishing Limited | Information & communication | 2019 |
| Intpay Ltd | Professional & scientific | 2012 |
| Intpeo Ltd | Administrative & support | 2022 |
| Intrinsic Impact Ltd | Professional & scientific | 2023 |
| Inveresk House Nominees Limited | Extraterritorial | 1976 |
| Invermor Ltd | Professional & scientific | 2007 |
| Investlord Limited | Administrative & support | 2000 |
| Investment Banking Solutions Ltd | Professional & scientific | 2016 |
| Invisible Hands Music Limited | Arts & recreation | 2002 |
| Ionized Studios Limited | Information & communication | 2016 |
| Ionutz Car Wash Ltd | Wholesale & retail | 2019 |
| Iota Logistics Ltd | Transport & logistics | 2021 |
| Iota Products Ltd | Transport & logistics | 2016 |
| Iownmyid Ltd | Extraterritorial | 2017 |
| IPS Pensions Limited | Financial services | 1991 |
| Iqscience Ltd | Professional & scientific | 2023 |
| Ironlatch Management Company Limited | Households | 2024 |
| Isabel & Joshua Ltd | Real estate | 2021 |
| Island Media Limited | Professional & scientific | 2014 |
| Islanders FJ Group Ltd | Wholesale & retail | 2022 |