| IN Car Technology Limited | Manufacturing | 2002 |
| IN2CARPENTRY Limited | Manufacturing | 2020 |
| IN2CONVERSIONS Limited | Construction | 2011 |
| IN2KITCHENS (Hampshire) Limited | Construction | 2013 |
| IN2OUT Projects Ltd | Construction | 2024 |
| IN2STONE Limited | Manufacturing | 2012 |
| Inauthor Limited | Information & communication | 2022 |
| INB Automation Limited | Wholesale & retail | 2019 |
| Incania Construction Solutions Ltd | Construction | 2026 |
| Incessus Casalis Limited | Education | 2023 |
| Independent Boilerhouse Supplies Limited | Extraterritorial | 2002 |
| Independent Youth Volunteer Support CIC | Education | 2025 |
| Indexpro Limited | Information & communication | 2021 |
| Indian Cottage Restaurant | | 1997 |
| Indigo Consultancy Southern Limited | Administrative & support | 2017 |
| Indus Valley Developments Ltd | Construction | 2025 |
| Industrial Boilerhouse Supplies Limited | Wholesale & retail | 1993 |
| Industrial Coatings Inspectors (Global) Ltd | Construction | 2021 |
| Industrial Engineering Plastics Limited | Manufacturing | 1986 |
| Industrial Maintenance Services Limited | Administrative & support | 2003 |
| Inferno Karate Limited | Education | 2024 |
| Infinite Form Limited | Manufacturing | 2018 |
| Infinitum Property Management Ltd | Real estate | 2021 |
| Infinity 8 Limited | Real estate | 2012 |
| Infinity Business Specialists Ltd | Professional & scientific | 2025 |
| Infinity England Limited | Other services | 2018 |
| Infinity Scada Systems Ltd | Manufacturing | 2023 |
| Inflata Glasgow Limited | Arts & recreation | 2018 |
| Inflata Peterborough Limited | Arts & recreation | 2019 |
| Infrared Service Solutions Ltd | Professional & scientific | 2025 |
| Inn-Dispensable Business Services Limited | Professional & scientific | 2000 |
| Inner Phoenix Coaching Limited | Health & social care | 2020 |
| Inner Technologies Limited | Information & communication | 2019 |
| Innovair Air Conditioning Ltd | Construction | 2023 |
| Innovate-Laboratory Ltd | Professional & scientific | 2024 |
| Innovatech Group Flooring Limited | Construction | 2024 |
| Innovation by Design Limited | Administrative & support | 2010 |
| Innovation Hair Academy Ltd | Other services | 2024 |
| Innovation I.T. Services Limited | Wholesale & retail | 2005 |
| Innovative Intelligence Ltd | Information & communication | 2024 |
| Innovative Life Coaching Ltd | Health & social care | 2017 |
| Innsupply Ltd | Wholesale & retail | 2026 |
| Inova Digital Services Ltd | Information & communication | 2021 |
| Insava Ltd | Hospitality | 2025 |
| Inspire Electrical Solutions Limited | Construction | 2021 |
| Inspire Others Ltd | Health & social care | 2026 |
| Installation South Ltd | Construction | 2017 |
| Integer Holdings Ltd | Construction | 2025 |
| Integra Site Solutions Limited | Construction | 2021 |
| Integrated Public Relations Limited | Professional & scientific | 1991 |
| Integrated Services (Hants) Limited | Construction | 2007 |
| Integrated Urgent Care 24 Limited | Health & social care | 2019 |
| Integrity Estate Planning Limited | Professional & scientific | 2016 |
| Integrity Financial Planning Limited | Financial services | 2007 |
| Interactive Management Agency Limited | Financial services | 2012 |
| Interactive Space Projects Limited | Professional & scientific | 2019 |
| International Diving Consultants Ltd | Transport & logistics | 2015 |
| International Insurance Technical Services Ltd | Financial services | 2018 |
| Introglobal Ltd | Professional & scientific | 2021 |
| Intruder Alert Systems Ltd | Administrative & support | 2014 |
| Intuitive Developments Ltd | Construction | 2024 |
| Inverleigh Road Freehold Ltd | Real estate | 2019 |
| Inview Systems Ltd | Administrative & support | 2007 |
| Invitations Entertainment Limited | Information & communication | 2015 |
| Invite Events Limited | Arts & recreation | 2022 |
| IOW AFD Ltd | Hospitality | 2024 |
| IP Boutique Limited | Professional & scientific | 2013 |
| Ipave Groundworks Ltd | Extraterritorial | 2010 |
| IQ365 Holdings Limited | Financial services | 2026 |
| Iqbal Company Holdings Ltd | Financial services | 2025 |
| Iraj Afshar Limited | Extraterritorial | 2022 |
| Iron Mill Approach Management Company Limited | Households | 2018 |
| Iron Oak Investments Limited | Real estate | 2025 |
| ISL Football Tours Limited | Arts & recreation | 2014 |
| Island Hazelton Limited | Hospitality | 2021 |
| Isle FM Ltd | Construction | 2021 |
| Isle Provenance Honey Limited | Agriculture & fishing | 2021 |
| Ismail Radiology Services Limited | Health & social care | 2022 |
| Isotek Power Systems Limited | Administrative & support | 2013 |
| Isroah Limited | Health & social care | 2024 |
| IT Four ME Ltd | Information & communication | 2011 |
| It's a Jungle Ltd | Administrative & support | 2013 |
| ITB Limited | Professional & scientific | 1995 |
| ITC Support Services Limited | Information & communication | 2002 |
| Itiq Limited | Information & communication | 2013 |
| ITP Limited | Professional & scientific | 2023 |
| Itrac Computing Ltd | Other services | 2011 |
| Izzie Haak Ltd | Arts & recreation | 2015 |
| J & D Holdings Limited | Professional & scientific | 2006 |
| J & G Rutter Agricultural Engineers Limited | Manufacturing | 2012 |
| J & J Norman LLP | | 2005 |
| J & L Financial Services Ltd | Financial services | 2015 |
| J & L Ventures Limited | Financial services | 2016 |
| J & M Contractors Limited | Construction | 2012 |
| J & P Burbidge Ltd | Construction | 2014 |
| J & S Drops Logistics Limited | Transport & logistics | 2025 |
| J and K Presentations Ltd | Arts & recreation | 2023 |
| J Brown Engineering Ltd | Information & communication | 2015 |
| J D Builders Southern Ltd | Construction | 2024 |
| J D T Properties Limited | Real estate | 2017 |