| Influencescore Ltd | Administrative & support | 2025 |
| Infomatik Solutions Ltd | Wholesale & retail | 2013 |
| Informadvance Solutions Ltd | Information & communication | 2026 |
| Infra-Shield Ltd | Construction | 2023 |
| Ingenious Entertainment Limited | Other services | 2023 |
| Ingram Court Residents Association Limited | Households | 1985 |
| Inklick Ltd | Arts & recreation | 2020 |
| Inksnap UK Ltd | Wholesale & retail | 2026 |
| Inner Ambitions Consulting Ltd | Professional & scientific | 2013 |
| Innovative Strategies Limited | Information & communication | 2014 |
| Innovify UK Ltd | Professional & scientific | 2011 |
| Innozyne Limited | Information & communication | 2016 |
| INS Cons Limited | Construction | 2017 |
| Insaan Skin Aesthetics Ltd | Other services | 2025 |
| Insine Consulting Ltd | Professional & scientific | 2022 |
| Insperanto Ltd | Professional & scientific | 2019 |
| Inspine Technologies Limited | Information & communication | 2016 |
| Inspiracore Ltd | Construction | 2026 |
| Inspiring Others Limited | Administrative & support | 2017 |
| INT Property Ltd | Real estate | 2025 |
| INT. Trading Ltd | Professional & scientific | 2007 |
| Integrate CMS Ltd | Professional & scientific | 2023 |
| Integrative Medical Health Limited | Health & social care | 2024 |
| Intelligence & Risks Consulting Limited | Professional & scientific | 2010 |
| Intelligent Goat Limited | Professional & scientific | 2014 |
| Interface Collective Ltd | Financial services | 2023 |
| Interface Facade Engineering Ltd | Professional & scientific | 2012 |
| Interim M&A Partners Limited | Professional & scientific | 2002 |
| Interlink Direct (UK) Ltd | Wholesale & retail | 2013 |
| Interlink Direct Holdings Limited | Financial services | 2018 |
| Interlink Direct Import and Export Ltd | Wholesale & retail | 2013 |
| Interlink Direct Limited | Wholesale & retail | 2000 |
| Interlink Direct Properties Limited | Real estate | 2018 |
| Interlink Direct Wholesale Ltd | Wholesale & retail | 2013 |
| Interlink Euro Limited | Hospitality | 2016 |
| International Business Seminars Limited | Professional & scientific | 2001 |
| International Corporation and Merger Services Ltd | Professional & scientific | 2026 |
| International Plastic Surgeons Limited | Health & social care | 2022 |
| Intersys Compliance Ltd | Professional & scientific | 2017 |
| Intupay Ltd | Professional & scientific | 2020 |
| Investing Essex Properties Limited | Households | 2023 |
| Investor Update Limited | Information & communication | 2016 |
| Invincible Investments Limited | Administrative & support | 2014 |
| Ioan Adin Ghiurutan Ltd | Administrative & support | 2023 |
| Iolt Limited | Education | 2013 |
| Ionyx Solutions Ltd | Information & communication | 2019 |
| Ipie Learning Centre Ltd | Information & communication | 2011 |
| IPS Power Consultancy Limited | Professional & scientific | 2023 |
| IPS Power Holdings Limited | Financial services | 2022 |
| IPS Power Services Ltd | Construction | 2024 |
| Ipsm Design Ltd | Professional & scientific | 2012 |
| Ipswich Performing Arts Ltd | Education | 2015 |
| Iqspeaks Limited | Information & communication | 2015 |
| Iqspeaks Properties Limited | Real estate | 2021 |
| IR Tech IT Consultancy Ltd | Information & communication | 2020 |
| Iresolv Ltd | Professional & scientific | 2024 |
| Iris Brand Limited | Administrative & support | 2013 |
| Iron Clad Media Ltd | Arts & recreation | 2025 |
| IS Glazing UK Limited | Construction | 2021 |
| Isla Analytics Limited | Administrative & support | 2014 |
| Islamic Hands | Health & social care | 2012 |
| Island FX Limited | Administrative & support | 2020 |
| Isle of Fleets Ltd | Administrative & support | 2024 |
| Ismailtyvoro Ltd | Wholesale & retail | 2025 |
| Isnaptech Ltd | Wholesale & retail | 2026 |
| Isufi Services Ltd | Construction | 2019 |
| IT Electrical Ltd | Construction | 2018 |
| IT Holdings U.K Limited | Financial services | 2018 |
| IT Squared Ltd. | Information & communication | 2016 |
| IT Web Professional Ltd | Information & communication | 2017 |
| It's UR Event Limited | Administrative & support | 2020 |
| Italtherm Ltd | Construction | 2019 |
| Itdoesthejob.Com Limited | Administrative & support | 2009 |
| Itees Property Ltd | Real estate | 2025 |
| Itog Ltd | Professional & scientific | 2026 |
| Itsmyturn CIC | Education | 2023 |
| Ivel Electrical Services Ltd | Other services | 2011 |
| Ivive Health Consultants Ltd | Health & social care | 2024 |
| Ivnas 76 Ltd | Construction | 2013 |
| Iyanu Financial Services Ltd | Financial services | 2025 |
| Iyra Ltd | Administrative & support | 2021 |
| J & S Ahmed Ltd | Real estate | 2013 |
| J & S Investments Assets Ltd | Real estate | 2025 |
| J Beasley Consulting Limited | Professional & scientific | 2013 |
| J Bilson Ltd | Professional & scientific | 2015 |
| J Bullman & Sons Building & Roofing Contractors Ltd | Other services | 2000 |
| J C Gills Properties Limited | Real estate | 2025 |
| J Deboy & Co Limited | Wholesale & retail | 2015 |
| J Heard Consultancy Limited | Professional & scientific | 2018 |
| J M C Building Contractors Ltd | Construction | 2011 |
| J P Driving Standards Consultancy Ltd | Administrative & support | 2023 |
| J T Shand Limited | Professional & scientific | 2022 |
| J Turner Ltd | Construction | 2016 |
| J&C (Europe) Limited | Wholesale & retail | 2024 |
| J&C Group Limited | Wholesale & retail | 2017 |
| J&Coj Consultancy Ltd | Financial services | 2016 |
| J&J Property Portfolio Limited | Real estate | 2023 |
| J&M Painters Limited | Construction | 2020 |
| J&M Solutions Ltd | Information & communication | 2025 |
| J&V Holdings Ltd | Real estate | 2019 |