| IN 'N' OUT Centres Retail Limited | Wholesale & retail | 2019 |
| IN a Flash Couriers Ltd | Transport & logistics | 2008 |
| IN a Flash Freight Limited | Transport & logistics | 2024 |
| IN a Flash Holdings Limited | Financial services | 2024 |
| IN House Recruiter International Limited | Administrative & support | 2019 |
| IN Music in Media C.I.C. | Arts & recreation | 2013 |
| IN Town Automotive Limited | Wholesale & retail | 2010 |
| In-House Electrical Limited | Wholesale & retail | 1989 |
| IN2SECURE Limited | Information & communication | 2020 |
| Incentifi Group Ltd | Financial services | 2022 |
| Incentifi Ltd | Administrative & support | 2023 |
| Incentivemk Limited | Other services | 2013 |
| Incipio Semper Porro Estates Limited | Real estate | 2025 |
| Inclusive Training Solutions Ltd | Education | 2007 |
| Inclusys Ltd | Information & communication | 2023 |
| Incom Design Limited | Professional & scientific | 2012 |
| Increation Tech Ltd | Information & communication | 2023 |
| Incubeator Limited | Extraterritorial | 2020 |
| Incura Seraph Ltd | Information & communication | 2024 |
| Independent Consulting Ltd | Professional & scientific | 2025 |
| Independent Finance Network Ltd | Information & communication | 2011 |
| Independent Pest Management & Insect Consultancy Ltd | Administrative & support | 2016 |
| Independent Warranty Limited | Extraterritorial | 2014 |
| Independiente Communications Limited | Information & communication | 2009 |
| Indetail Architecture & Consultancy Ltd | Professional & scientific | 2026 |
| Indexate Ltd | Information & communication | 2015 |
| Indi Line Group Limited | Construction | 2020 |
| Indi Local Ltd | Information & communication | 2024 |
| India Grill Ltd | Hospitality | 2019 |
| Indian Hindu Welfare Organisation (Northampton) Limited | Education | 2005 |
| Indian Khani Limited | Hospitality | 2022 |
| Indian Mirchi Ltd | Hospitality | 2023 |
| Indian Ocean Gateway Limited | Professional & scientific | 2026 |
| Indie Masala Ltd | Hospitality | 2025 |
| Indigenous Brands Ltd | Wholesale & retail | 2024 |
| Indigo SA Ltd | Households | 2024 |
| Indoor Adventure Limited | Arts & recreation | 2003 |
| Indulgence (UK) Ltd | Hospitality | 2005 |
| Industrial Control Distributors (Holdings) Ltd | Financial services | 2012 |
| Industrial Heat Research Limited | Professional & scientific | 2025 |
| Industrial Pallet Solutions Limited | Administrative & support | 2021 |
| Industrial,Medical and Safety Services Limited | Extraterritorial | 1994 |
| Industry Insights Investments Ltd | Real estate | 2022 |
| Indy Brands Limited | Arts & recreation | 2013 |
| Indy IT Limited | Extraterritorial | 2012 |
| Indy Ware Limited | Information & communication | 2002 |
| Ineco OZE Ltd | Wholesale & retail | 2014 |
| Infaaq Ltd | Administrative & support | 2017 |
| Infinis (California) Limited | Construction | 2021 |
| Infinis (Caton Road) Energy Storage Limited | Administrative & support | 2017 |
| Infinis (Ford Oaks) Limited | Energy | 2022 |
| Infinis (Gowerton) Limited | Energy | 2022 |
| Infinis (Oaklands) Limited | Construction | 2020 |
| Infinis (Peel Road) Energy Storage Limited | Administrative & support | 2017 |
| Infinis (Re-Gen) Limited | Energy | 1918 |
| Infinis (Shoreside) Limited | Energy | 2021 |
| Infinis Alternative Energies Limited | Energy | 2013 |
| Infinis Energy Group Holdings Limited | Financial services | 2016 |
| Infinis Energy Management Limited | Financial services | 2016 |
| Infinis Energy Services Limited | Other services | 2010 |
| Infinis Energy Storage Limited | Energy | 2008 |
| Infinis Limited | Energy | 2006 |
| Infinis Solar Developments Limited | Construction | 2019 |
| Infinis Solar Holdings Limited | Financial services | 2019 |
| Infinis Wind Limited | Financial services | 2026 |
| Infinit Gear Limited | Administrative & support | 2021 |
| Infinit Properties Ltd | Real estate | 2022 |
| Infinita Concepts UK Ltd | Information & communication | 2023 |
| Infinite 7 Trading Ltd | Manufacturing | 2025 |
| Infinite Computing Ltd | Wholesale & retail | 2020 |
| Infinite Improbability Inc Holdings Limited | Real estate | 2025 |
| Infinite Wonder Limited | Manufacturing | 2025 |
| Infiniti Foods Limited | Hospitality | 2015 |
| Infinity 2 Limited | Information & communication | 1996 |
| Infinity 8 Elevate and Empower Ltd | Arts & recreation | 2024 |
| Infinity and Beyond Enterprises Ltd | Wholesale & retail | 2022 |
| Infinity D-Ls Ltd | Wholesale & retail | 2024 |
| Infinity Electrical Contractors Ltd | Construction | 2013 |
| Infinity Electrical Installations Ltd | Construction | 2024 |
| Infinity Estate Agency Ltd | Real estate | 2025 |
| Infinity Fine Jewellery Ltd | Wholesale & retail | 2019 |
| Infinity Geeks Ltd | Information & communication | 2025 |
| Infinity Hair & Beauty 2024 Ltd | Other services | 2024 |
| Infinity Hair & Beauty LAB Ltd | Education | 2022 |
| Infinity Reliance Limited | Wholesale & retail | 2009 |
| Infinity Rise Ltd | Real estate | 2023 |
| Infinity Vending Ltd | Hospitality | 2024 |
| Infinity Water Treatment Ltd | Construction | 2018 |
| Infinity Wedding Planning Services Limited | Professional & scientific | 2009 |
| Infinityv Ltd | Construction | 2024 |
| Influx Gallery Ltd | Wholesale & retail | 2022 |
| Infocurious Ltd | Professional & scientific | 2025 |
| Infrabid Consulting Limited | Professional & scientific | 2012 |
| Infrastructure Development Group Limited | Construction | 2019 |
| Infrastructure Technologies Group Limited | Information & communication | 2021 |
| Inga’S Secrets Aesthetics Ltd | Health & social care | 2022 |
| Ingear Solutions Limited | Professional & scientific | 2011 |
| Ingleby (2016) Limited | Professional & scientific | 2016 |
| Inglecade Limited | Construction | 2018 |
| Inglis Imports Ltd | Wholesale & retail | 2020 |