| Incar (South East) Limited | Wholesale & retail | 2006 |
| Inclusify Digital UK Ltd | Other services | 2025 |
| Incms Ltd | Wholesale & retail | 2017 |
| Incomplete Inc Ltd | Hospitality | 2025 |
| Incrementum Business Consultancy Ltd | Professional & scientific | 2020 |
| Independent Living With Care Limited | Hospitality | 2008 |
| Independent Secondary Care Advisory Service Limited | Health & social care | 2012 |
| Index Property Services Ltd | Real estate | 2020 |
| Indian Food Eastbourne Ltd | Hospitality | 2025 |
| Indie Exped Ltd | Administrative & support | 2025 |
| Indie Health Ltd | Health & social care | 2024 |
| Indigo Architecture & Design Limited | Construction | 2005 |
| Indigo IMP Consulting Ltd | Professional & scientific | 2023 |
| Indigo Inc Limited | Professional & scientific | 2023 |
| Indigo Industries Limited | Financial services | 2022 |
| Indigo UK Group Ltd | Wholesale & retail | 2022 |
| Indine South East Ltd | Hospitality | 2022 |
| Indramrut Limited | Health & social care | 2022 |
| Indus Mega Finance Limited | Financial services | 2014 |
| Industrial Therapy Organisation (Thames) Limited | Health & social care | 1963 |
| Infinite Being Ltd. | Public administration | 2018 |
| Infinite Electrical Solutions (Sussex) Limited | Construction | 2018 |
| Infinite INK22 Ltd | Other services | 2022 |
| Infinite Sport Ltd | Education | 2025 |
| Inforima Ltd | Information & communication | 2023 |
| Ingel Limited | Real estate | 2014 |
| Ingenui Limited | Professional & scientific | 2017 |
| Ingenyus Medical Ltd | Health & social care | 2011 |
| Inglenook Medical Limited | Health & social care | 2020 |
| Initiate Consulting Limited | Professional & scientific | 1998 |
| Innerwick Storage Ltd | Administrative & support | 2021 |
| Innings Developments Limited | Real estate | 2014 |
| Innotech Group (UK) Limited | Education | 2002 |
| Innovating Reality Limited | Professional & scientific | 2020 |
| Innovation and Design Ltd | Construction | 2013 |
| Innovation Construction Design & Build Surrey Limited | Construction | 2026 |
| Innovationpsp Limited | Professional & scientific | 2024 |
| Inoh Ltd | Professional & scientific | 2013 |
| Inside Global Limited | Professional & scientific | 2010 |
| Inside OUT Designs Ltd | Professional & scientific | 2017 |
| Insieme Kent Ltd | Agriculture & fishing | 2025 |
| Insight Employment Limited | Administrative & support | 2010 |
| Insight International Corporation Limited | Wholesale & retail | 1991 |
| Insite Specialists Ltd | Construction | 2016 |
| Insley Consulting Ltd | Other services | 2014 |
| Inspiration 2 Dance Academy Ltd | Education | 2016 |
| Inspiration 2 Dance Ltd | Arts & recreation | 2010 |
| Inspired AI Limited | Information & communication | 2018 |
| Inspired Carpets Limited | Wholesale & retail | 2003 |
| Inspired Humans Ltd | Arts & recreation | 2025 |
| Inspya Ltd | Professional & scientific | 2013 |
| Instepp Fitness Limited | Wholesale & retail | 2021 |
| Institute for Human Rights & Business Limited | Other services | 2009 |
| Insurance Search Ltd | Administrative & support | 2015 |
| Intafast Limited | Wholesale & retail | 1988 |
| Integral Logistics Limited | Transport & logistics | 2015 |
| Integrate London Ltd | Information & communication | 2003 |
| Integrated Community Care Ltd | Health & social care | 2014 |
| Integrity Dental Limited | Health & social care | 2021 |
| Integrity Property Ltd | Real estate | 2026 |
| Intelligentassetadvisory Ltd | Professional & scientific | 2024 |
| Intelliwan Ltd | Administrative & support | 2018 |
| Interlock Systems Limited | Professional & scientific | 1992 |
| Internal Auditors Ltd | Professional & scientific | 2025 |
| International Moving Services UK Limited | Transport & logistics | 2016 |
| Intouch Business (UK) LLP | | 2010 |
| Intouch Business Limited | Professional & scientific | 2007 |
| Intrinsic Facilities Engineering Limited | Professional & scientific | 2013 |
| Intrinsic Facilities Management Ltd | Professional & scientific | 2015 |
| Investment Company Eastbourne Limited | Administrative & support | 2018 |
| Invictus Roofing Ltd | Construction | 2014 |
| Inzen Limited | Professional & scientific | 2026 |
| IP Studio Physiotherapy Ltd | Education | 2024 |
| IPC Construction Limited | Construction | 2008 |
| IQ Group Southern Holdings Ltd | Administrative & support | 2026 |
| Iqfm Ltd | Other services | 2019 |
| Iranian Pasargad Ltd | Hospitality | 2024 |
| Iremia Consulting Ltd | Professional & scientific | 2016 |
| IRF Scaffolding Limited | Construction | 2023 |
| IRM Enterprises Limited | Agriculture & fishing | 2005 |
| Iron Will Holdings Ltd | Other services | 2025 |
| Irongrid Tech Ltd | Information & communication | 2025 |
| Ironhorse Professionals Ltd | Hospitality | 2025 |
| Irresistible Skin Clinic Ltd | Other services | 2024 |
| ISA Global IT Limited | Hospitality | 2015 |
| Isabel Vogel Ltd | Professional & scientific | 2012 |
| Ischma Investments Ltd | Real estate | 2024 |
| Isheish Limited | Health & social care | 2024 |
| Isla Yacht Group Ltd | Administrative & support | 2025 |
| Islaks Ltd | Professional & scientific | 2022 |
| Island Social Ltd | Hospitality | 2017 |
| Ismail Furniture Ltd | Wholesale & retail | 2014 |
| Ismail Property Ltd | Real estate | 2019 |
| Issi PAY Ltd | Wholesale & retail | 2023 |
| Istan Barber Ltd | Other services | 2025 |
| Istanbul Aslan Ltd | Hospitality | 2019 |
| Istanbul Sampiyon Ltd | Hospitality | 2026 |
| Isuntza Limited | Real estate | 2011 |
| IT Oasis Digital Ltd | Wholesale & retail | 2026 |
| It's Dog Time Limited | Other services | 2022 |