| Indigo Properties Solutions Ltd | Construction | 2025 |
| Indigo Solutions Limited | Real estate | 2015 |
| Indigo Swan Limited | Professional & scientific | 2009 |
| Indigo Tattoo and Piercing Ltd | Other services | 2023 |
| Indirect Tax Services Ltd | Professional & scientific | 2010 |
| Indo UK PVT Ltd | Wholesale & retail | 2024 |
| Indo UK Retail Ltd | Wholesale & retail | 2025 |
| Induct EA Limited | Education | 2017 |
| Inductive Logic Ltd | Wholesale & retail | 2009 |
| Indulge Desserts Limited | Hospitality | 2017 |
| Indulgence Chocolates Ltd | Wholesale & retail | 2020 |
| Induluxe Resources Ltd | Health & social care | 2023 |
| Industrial & Welding Ovens Limited | Manufacturing | 1973 |
| Industrial Boys Limited | Real estate | 2019 |
| Industrial Building Maintenance Ltd | Construction | 2013 |
| Industrial Domestic Boiler Services Ltd | Construction | 2015 |
| Inext Petroleum Ltd | Manufacturing | 2019 |
| Infection Control Enterprise Limited | Manufacturing | 2005 |
| Inferno Alarms Ltd | Public administration | 2024 |
| Infinisyn AI Ltd | Information & communication | 2025 |
| Infinite Compassion Limited | Health & social care | 2023 |
| Infinite Electrics Ltd | Construction | 2021 |
| Infinite Spaces Ltd | Administrative & support | 2003 |
| Infinitee Solutions Ltd | Professional & scientific | 2015 |
| Infinitii Ltd | Hospitality | 2019 |
| Infinity CNC Ltd | Manufacturing | 2022 |
| Infinity Green Technology Ltd | Information & communication | 2026 |
| Infinity Hospitality 1 Ltd | Hospitality | 2018 |
| Infinity Keyz Limited | Real estate | 2020 |
| Influence Display Limited | Professional & scientific | 2021 |
| Infopragmatica Limited | Information & communication | 1999 |
| Informix Solutions Limited | Information & communication | 2025 |
| Infralogic (UK) Ltd | Information & communication | 2012 |
| Infrared Integrated Systems Limited | Professional & scientific | 1996 |
| Infrastructure Survey Solutions Limited | Professional & scientific | 2012 |
| Ingendehsa Investments Ltd | Energy | 2025 |
| Ingle Property Ltd | Real estate | 2024 |
| Inglis Consulting Limited | Professional & scientific | 2012 |
| Ingram Micro Services Holdings Ltd | Information & communication | 2000 |
| Ingram Micro Services Ltd | Other services | 1998 |
| Initial Flooring Ltd | Construction | 2020 |
| Initium Apps Limited | Information & communication | 2025 |
| Initium Management Ltd | Professional & scientific | 2020 |
| Initium Technology Limited | Information & communication | 2023 |
| Injectd Ltd | Manufacturing | 2017 |
| INK Bespoke Ltd | Professional & scientific | 2015 |
| INK FLO Creative Limited | Arts & recreation | 2012 |
| Inka Contractors Ltd | Construction | 2017 |
| Inking Ltd | Information & communication | 2017 |
| Innate Family Chiropractic Centre Limited | Health & social care | 2000 |
| Innate Needs C.I.C. | Health & social care | 2022 |
| Inncount Limited | Administrative & support | 2008 |
| Inner Voices Ltd | Arts & recreation | 2020 |
| Innerbit Therapy Services Ltd | Health & social care | 2026 |
| Innerglow Limited | Construction | 2019 |
| Innershed Ltd | Information & communication | 2005 |
| Innerspark Limited | Wholesale & retail | 2026 |
| Innertrends Ltd | Information & communication | 2015 |
| Innovare Recruitment Ltd | Administrative & support | 2023 |
| Innovation Xperts Limited | Hospitality | 2018 |
| Innovative Design Systems Limited | Construction | 2000 |
| Innovative IT Serv Ltd | Information & communication | 2026 |
| Innovo Warehouse Ltd | Wholesale & retail | 2020 |
| Inoscape Limited | Manufacturing | 2012 |
| Inova Consultants Limited | Professional & scientific | 2015 |
| Inovace Ltd | Manufacturing | 2014 |
| Inovit Consulting Limited | Professional & scientific | 2023 |
| Inproperty Media Ltd | Real estate | 2017 |
| Inside Bird Ltd | Other services | 2025 |
| INSIDE2OUTSIDE Limited | Construction | 1991 |
| Insight Accountancy Services Ltd | Professional & scientific | 2016 |
| Insight East Limited | Professional & scientific | 2013 |
| Insight Ecology Ltd | Professional & scientific | 2017 |
| Insight Group Holdings Limited | Financial services | 2020 |
| Insight Health Solutions Ltd | Financial services | 2023 |
| Insight Horizon Limited | Professional & scientific | 2023 |
| Insight Prime Ltd | Extraterritorial | 2021 |
| Insight Private Clients Limited | Financial services | 2005 |
| Insight Private Finance Limited | Financial services | 2004 |
| Insight Property Holdings Ltd | Extraterritorial | 2022 |
| Insight Wealth Limited | Financial services | 2002 |
| Insightbenefits Limited | Financial services | 2024 |
| Insightful Properties Ltd | Real estate | 2022 |
| Insignia Healthcare Group Limited | Health & social care | 2011 |
| INSIGNIA16 Ltd | Administrative & support | 2016 |
| Insites Digital Limited | Professional & scientific | 2014 |
| Insphigher Ltd | Construction | 2020 |
| Inspiralis Limited | Professional & scientific | 2006 |
| Inspiration Services Limited | Education | 2016 |
| Inspiration Trust | Education | 2012 |
| Inspire Design & Development Limited | Construction | 2004 |
| Inspire Properties Group Ltd | Extraterritorial | 2023 |
| Inspire Training Group (East Anglia) Ltd | Education | 2019 |
| Inspireaccord Limited | Financial services | 2024 |
| Inspired Architectural Solutions Limited | Manufacturing | 2018 |
| Inspired Building Group Ltd | Construction | 2024 |
| Inspired Building Services Ltd | Construction | 2007 |
| Inspired Inspirations Ltd | Other services | 2019 |
| Inspired Jewellery Limited | Wholesale & retail | 2008 |
| Inspired Motorsport Ltd | Wholesale & retail | 2023 |