| Hydra EVC Ltd | Wholesale & retail | 2021 |
| Hydro Outlet Ltd | Health & social care | 2025 |
| I ALB Limited | Information & communication | 2021 |
| I E M (UK) Limited | Professional & scientific | 2005 |
| I SPY Coffee & Water (Europe) Ltd | Administrative & support | 2017 |
| I T Office Supplies Ltd | Wholesale & retail | 2021 |
| I-Arch Consulting Limited | Professional & scientific | 2009 |
| I-Klenz Limited | Administrative & support | 2025 |
| IA Entreprises Ltd | Professional & scientific | 2024 |
| Iactivatelove Ltd | Manufacturing | 2020 |
| IAN Norton LEA International Limited | Professional & scientific | 2004 |
| IAN Ward Security Services Ltd | Administrative & support | 2001 |
| Ibelieve in ME Limited | Education | 2022 |
| Ibex Technologies Ltd | Information & communication | 2024 |
| Ibsimple (International) Limited | Manufacturing | 2020 |
| Ibsimple (UK) Limited | Manufacturing | 2020 |
| Ibtl Ltd | Transport & logistics | 2023 |
| IC Dent Ltd | Health & social care | 2025 |
| IC Optics Ltd | Health & social care | 2022 |
| Icare Security Systems Ltd | Administrative & support | 2014 |
| Icdm Solutions Ltd | Construction | 2024 |
| Ice Active Solutions Ltd | Construction | 2019 |
| ICJ Heating & A/C Ltd | Construction | 2023 |
| Iclight Limited | Administrative & support | 2012 |
| Icon Property Care Ltd | Construction | 2026 |
| Icontrols London Ltd | Professional & scientific | 2015 |
| Icover Limited | Wholesale & retail | 2023 |
| ID Property Investment Limited | Extraterritorial | 2006 |
| Ideal Direct Solutions Ltd | Financial services | 2019 |
| Ideal Parts Ltd | Wholesale & retail | 2024 |
| Identi-Fire Limited | Professional & scientific | 1994 |
| IDP Build Ltd | Construction | 2020 |
| IEG Utilities Limited | Energy | 2024 |
| IF (Intl) Ltd | Professional & scientific | 2022 |
| Ifar Ltd | Wholesale & retail | 2024 |
| Ifma Trans Limited | Transport & logistics | 2016 |
| IFP Ltd | Professional & scientific | 2006 |
| Ifps Ltd | Administrative & support | 2008 |
| Ignite Signs Limited | Other services | 2014 |
| IH Legacy Ltd | Wholesale & retail | 2026 |
| Iitmechanic Ltd | Manufacturing | 2025 |
| IKB Furniture Limited | Wholesale & retail | 2010 |
| Ikoma Limited | Households | 2018 |
| IL Gusto (Essex) Limited | Hospitality | 2024 |
| IL Mondo Restaurant Ltd | Hospitality | 2018 |
| IL Salvatore Limited | Hospitality | 2019 |
| Illyrian Stone Atelier Limited | Manufacturing | 2026 |
| Imaat Group Ltd | Hospitality | 2021 |
| IMI Corp Ltd | Hospitality | 2023 |
| Immaculate Catering Services Ltd | Hospitality | 2023 |
| Imperial Optical Company Ltd. | | 1989 |
| Impire Pizza Ltd | Hospitality | 2026 |
| Imyna Limited | Information & communication | 2018 |
| IN OUT Living Ltd | Wholesale & retail | 2025 |
| Inbox UK Limited | Wholesale & retail | 2017 |
| Inco Supplies Ltd | Wholesale & retail | 2020 |
| Independent Living Services (S.E.) Ltd | Health & social care | 2018 |
| Independent Media Alliance Ltd | Information & communication | 2022 |
| Index Healthcare Ltd | Administrative & support | 2023 |
| Indie Game Publishing Limited | Information & communication | 2023 |
| Indigo Create Limited | Professional & scientific | 2020 |
| Indirock Ltd | Hospitality | 2019 |
| Indulge Holdings Limited | Hospitality | 2015 |
| Industrial Analysis Limited | Professional & scientific | 1989 |
| Infernix Computing Limited | Other services | 2013 |
| Infiniofoods Ltd | Hospitality | 2024 |
| Infinite Creativity Ltd | Professional & scientific | 2017 |
| Infinite Design Ideas UK Ltd | Wholesale & retail | 2013 |
| Infinity Seating Solutions Limited | Wholesale & retail | 2009 |
| Infinity Showbar Limited | Hospitality | 2020 |
| Infinity Sources Ltd | Real estate | 2020 |
| INFINITY888 Limited | Information & communication | 2014 |
| Infoview Solutions Limited | Information & communication | 2011 |
| Infrastructure Sustainability and Natural Environment Limited | Professional & scientific | 2025 |
| Ingenious Fundraising Limited | Professional & scientific | 2009 |
| Ingenium Automotive Ltd | Professional & scientific | 2012 |
| Inkersall Road (Chesterfield) Management Company Limited | Households | 2022 |
| Inlet GAS, Heating and Plumbing Ltd | Construction | 2022 |
| Inner Harmony EST 2016 Ltd | Health & social care | 2025 |
| Inner Strength Group Limited | Health & social care | 2025 |
| Innovate Engineering Limited | Wholesale & retail | 2025 |
| Innovate Enterprise Solutions Ltd | Professional & scientific | 2019 |
| Innovation Business Vision Limited | Professional & scientific | 1987 |
| Innovation Programmes & Projects Limited | Professional & scientific | 2004 |
| Inseen Construction Limited | Construction | 2005 |
| Inside OUT Clearances Limited | Wholesale & retail | 2023 |
| Insight Integrated Solutions Limited | Information & communication | 1995 |
| Insignia Building Services Limited | Construction | 2017 |
| Insignia Building Structures Limited | Extraterritorial | 2021 |
| Insignia Fire Protection Services Ltd | Public administration | 2024 |
| Insignia Roofing Services Ltd | Construction | 2026 |
| Inspired Bathrooms by Michael Georgiou Limited | Construction | 2020 |
| Insure & Go Insurance Services Limited | Administrative & support | 2000 |
| Intech Fire & Security Limited | Administrative & support | 2009 |
| Integra Cloud Solutions Ltd | Information & communication | 2014 |
| Intellikon AI Ltd | Information & communication | 2025 |
| Interbridge Group Ltd | Administrative & support | 2025 |
| Interiors Your Way Limited | Manufacturing | 2013 |
| Internode Limited | Information & communication | 1991 |
| Invaluable Care Ltd | Health & social care | 2023 |