| Independent Financial Advisors (1987) Limited | Financial services | 1987 |
| Independent Paint and Coatings Supplies Limited | Wholesale & retail | 2023 |
| Independent Property Lawyers Limited | Professional & scientific | 2008 |
| Independent Security Limited | Other services | 1998 |
| Index Enclosures Ltd | Manufacturing | 2010 |
| India Rocks Corporation Ltd | Administrative & support | 2020 |
| Indica Forestry Ltd | Agriculture & fishing | 2019 |
| Indicator Limited | Information & communication | 1996 |
| Indiebob Holdings Limited | Professional & scientific | 2025 |
| Indiflow Ltd | Information & communication | 2025 |
| Indigo Direct Ltd | Wholesale & retail | 2016 |
| Indigo Luxury Hospitality Ltd | Hospitality | 2022 |
| Indigo Winter Consulting Ltd | Information & communication | 2012 |
| Indoor Sports Arena Limited | Extraterritorial | 2009 |
| Industrial Doors & Cladding Limited | Construction | 2014 |
| Industrial Hub Properties Ltd | Real estate | 2023 |
| Inevitable LJW Ltd | Construction | 2017 |
| Infinite Iris Ltd | Professional & scientific | 2010 |
| Infinity Loom Ltd | Information & communication | 2024 |
| Inflate Decorate Ltd | Wholesale & retail | 2020 |
| Inform Brickwork Services Ltd | Construction | 2024 |
| Infotech Group Ltd | Information & communication | 2019 |
| Ingenx Limited | Professional & scientific | 2003 |
| Ingham Pinnock Associates Limited | Professional & scientific | 2012 |
| Inglenook Estates Limited | Real estate | 2019 |
| Inglewood Fire & Flues Ltd | Wholesale & retail | 2021 |
| Ingole Limited | Health & social care | 2019 |
| Inisy Consulting Limited | Information & communication | 2018 |
| INITI8 AV Ltd | Construction | 2019 |
| Initial Systems Limited | Construction | 2008 |
| Inivur Limited | Real estate | 2024 |
| INK to Barrow Limited | Administrative & support | 2023 |
| Inkerman (Group) Limited | Administrative & support | 1995 |
| Inkerman Cyber Limited | Information & communication | 2007 |
| Inkerman Group Medical Services Limited | Administrative & support | 1995 |
| Inkerman Group Special Projects Ltd | Administrative & support | 2000 |
| Inkerman Private Clients Limited | Administrative & support | 1997 |
| INKS4YOU Ltd | Wholesale & retail | 2020 |
| Inn-Victa | | 1994 |
| Inna's House Ltd | Construction | 2024 |
| Inner Solutions Limited | Health & social care | 2012 |
| Innflair Ltd | Hospitality | 2015 |
| Innosport Marketplace Ltd | Wholesale & retail | 2023 |
| Innotronix Ltd | Wholesale & retail | 2019 |
| INNOV8 Training Ltd | Education | 2012 |
| Innovate Capital Partners Limited | Professional & scientific | 2026 |
| Innovate College London Ltd | Real estate | 2023 |
| Innovate Medicals Limited | Health & social care | 2022 |
| Innozify Ltd | Information & communication | 2019 |
| Inprint Systems Limited | Administrative & support | 1998 |
| Inside OUT Secure Ltd. | Administrative & support | 2018 |
| Insight Safety Services Ltd | Administrative & support | 2023 |
| Insight Solution Accounts Limited | Professional & scientific | 2024 |
| Insightcore Ltd | Information & communication | 2025 |
| Insignia Projects Limited | Professional & scientific | 2021 |
| Inspire Nutrition Ltd | Health & social care | 2019 |
| Inspired GAS Service Ltd | Construction | 2015 |
| Instant Gifts International Limited | Wholesale & retail | 1987 |
| Instant Magic Ltd | Information & communication | 2023 |
| Inta Lofts Limited | Construction | 2012 |
| Intanon Media Ltd | Professional & scientific | 2026 |
| Integra South Limited | Information & communication | 2025 |
| Integrated Business Planning Limited | Professional & scientific | 2007 |
| Integrated Care 24 | Health & social care | 1996 |
| Integrated Construction Services Limited | Construction | 2007 |
| Integrated Solutions & Services Limited | Information & communication | 2005 |
| Integrated Technologies (Holdings) Limited | Manufacturing | 1991 |
| Integrated Technologies Limited | Manufacturing | 1977 |
| Integrity Leverage Africa (ILA) PVT Ltd | Professional & scientific | 2026 |
| Intek Resources (Consulting) Limited | Administrative & support | 2013 |
| Intelligent Insulation Limited | Administrative & support | 2014 |
| Intelligent Security Services Inc Limited | Construction | 2025 |
| Intelligent Testing Auditing Limited | Professional & scientific | 2019 |
| Inten Facilities Ltd | Administrative & support | 2018 |
| Interactivem Limited | Arts & recreation | 2003 |
| Intercapitalplus Limited | Professional & scientific | 2011 |
| Intercontinental CAD Services Ltd | Professional & scientific | 2021 |
| Intercontinental Health Hub Ltd | Health & social care | 2025 |
| Intergraition Group Ltd | Information & communication | 2025 |
| Interlocked Solutions Limited | Information & communication | 2026 |
| International Biodiversity Consultants Limited | Professional & scientific | 2019 |
| International Cargo Transits Limited | Transport & logistics | 2008 |
| International Confectionery Ltd | Wholesale & retail | 2025 |
| International Glaucoma Association Limited(The) | Professional & scientific | 1977 |
| International News Services Limited | Professional & scientific | 2000 |
| International Positive Education Network | Education | 2015 |
| International Power Shot Ltd | Extraterritorial | 2025 |
| International Property Trust Limited | Construction | 1996 |
| International TCG Ltd | Wholesale & retail | 2026 |
| International Work at Height Seminar Ltd | Other services | 2025 |
| Internet Marketing Business Limited | Administrative & support | 2010 |
| Interpretis Limited | Other services | 2010 |
| Intertag Media Limited | Administrative & support | 2008 |
| Intgene Solutions Limited | Information & communication | 2015 |
| Intogreat Coaching Limited | Administrative & support | 2019 |
| Intothefire Electrical Services Ltd | Construction | 2015 |
| Intu Property Limited | Real estate | 2019 |
| Intuitive AIM Consultancy Ltd | Information & communication | 2014 |
| Inventex Solutions Limited | Wholesale & retail | 2012 |
| Inveris Training Solutions Limited | Public administration | 1992 |