| I Tech Expert Ltd | Wholesale & retail | 2024 |
| I&L Consulting Limited | Professional & scientific | 2020 |
| I&N Ltd | Construction | 2016 |
| I-Promise Limited | Wholesale & retail | 2013 |
| I.S Aesthetics Ltd | Health & social care | 2023 |
| I.Say Medical Consulting Limited | Health & social care | 2026 |
| IAN Bower Enterprises Limited | Professional & scientific | 2011 |
| Ianthe Consulting Ltd | Information & communication | 2022 |
| IAR Ventures Ltd | Hospitality | 2024 |
| IB Instant IT Limited | Information & communication | 2012 |
| Ibdaw Limited | Other services | 2017 |
| Ibitqa Ltd | Information & communication | 2011 |
| Iceberg HR Limited | Professional & scientific | 2019 |
| ICS Associates Ltd | Financial services | 2026 |
| IDA Wadhams Ltd | Professional & scientific | 2019 |
| Idea Desk Ltd | Manufacturing | 2019 |
| Ifma Ltd | Real estate | 2018 |
| Ihop Limited | Other services | 2023 |
| IHP Consulting Limited | Information & communication | 2023 |
| Iken Care and Support Limited | Health & social care | 2023 |
| Ikigai Executive Coaching Limited | Professional & scientific | 2022 |
| Ikon Intermediate Limited | Administrative & support | 2018 |
| Ikon Parent Limited | Administrative & support | 2018 |
| Ikon Science Limited | Information & communication | 2001 |
| Ikventure Store Ltd | Wholesale & retail | 2023 |
| Imani Properties Ltd | Information & communication | 2025 |
| IMF Automotive Ltd | Wholesale & retail | 2026 |
| Impala Productions Limited | Administrative & support | 1998 |
| Impct Studio Limited | Information & communication | 2024 |
| Imperial Design Consulting Limited | Administrative & support | 2021 |
| Improvise Events Ltd | Education | 2021 |
| Imregeoffrey Ltd | Financial services | 2026 |
| Imzota Limited | Professional & scientific | 2022 |
| In.Cos Idea Ltd | Construction | 2016 |
| IN4ALL Limited | Administrative & support | 2019 |
| Incaline Enterprises Ltd | Information & communication | 2016 |
| Incubiq Solutions Limited | Information & communication | 2013 |
| Indigo Medical Clinic Ltd | Health & social care | 2021 |
| Infinite Appletree Ltd | Information & communication | 2017 |
| Infinite London Limited | Construction | 2017 |
| Infinite Media 8 Ltd | Professional & scientific | 2026 |
| Infinite Properties Group Ltd | Real estate | 2023 |
| Infinity Talent Ltd | Hospitality | 2024 |
| Infinity Therapy Limited | Health & social care | 2023 |
| Infinix Store Limited | Wholesale & retail | 2025 |
| Infracloud Limited | Information & communication | 2017 |
| Infraview Limited | Administrative & support | 2016 |
| Infun Ltd | Wholesale & retail | 2017 |
| Inilume Ltd | Information & communication | 2021 |
| INK Critter Ltd. | Information & communication | 2014 |
| Inkworks Management Company Limited | Households | 2011 |
| Inner-Beauty Limited | Other services | 2025 |
| Innoflight Ltd | Professional & scientific | 2024 |
| Innohealth Consultancy Ltd | Health & social care | 2024 |
| Insaxocondita Limited | Professional & scientific | 2023 |
| Inside OUT Agencies Limited | Wholesale & retail | 2019 |
| Insideout Boxing Ltd | Other services | 2023 |
| Inspirational Perspectives Limited | Professional & scientific | 2022 |
| Inspire Hope Limited | Health & social care | 2024 |
| Inspire Management Group Ltd | Health & social care | 2019 |
| Inspired Management Solutions Limited | Professional & scientific | 2024 |
| Integrated Circles Design & Support Services Ltd | Professional & scientific | 2014 |
| Integrated Medicine and Chinese Medicine Professionals Ltd | Health & social care | 2019 |
| Integritas Properties Ltd | Real estate | 2018 |
| Intelitech Ltd | Real estate | 2013 |
| Inteliweb Ltd | Information & communication | 2021 |
| Interim HR Consultancy Limited | Administrative & support | 2012 |
| Interior Furniture Ltd | Wholesale & retail | 2018 |
| International Traders and Distributors Limited | Wholesale & retail | 2023 |
| International Wines & Spirits Ltd | Wholesale & retail | 2026 |
| Intersect Property Ltd | Real estate | 2023 |
| Intersect Surveys Ltd | Professional & scientific | 2015 |
| Inverbrae Management Company Limited | Households | 1992 |
| Invertiv Limited | Other services | 2019 |
| Investor Media Limited | Information & communication | 2013 |
| Invicta Advisory Limited | Professional & scientific | 2010 |
| Invicta Court Maintenance Limited | Real estate | 1964 |
| Ipoint Media Ltd | Professional & scientific | 2023 |
| Iris World Limited | Administrative & support | 2025 |
| Iron Ladies Surrey Ltd | Other services | 2020 |
| Isazi UK Ltd | Information & communication | 2024 |
| ISG Esolutions Private Limited | Administrative & support | 2014 |
| IT Penguin Ltd | Information & communication | 2012 |
| It-Wire Ltd | Information & communication | 2020 |
| Itgoalz Ltd | Information & communication | 2017 |
| IVA Catering Ltd | Hospitality | 2024 |
| IVA Gardening Express Limited | Administrative & support | 2020 |
| Ivymist Limited | Households | 1994 |
| Iwbf Limited | Professional & scientific | 2024 |
| Iyria Financial Services Ltd | Financial services | 2025 |
| IZG Consulting Limited | Professional & scientific | 2016 |
| J C B S Limited | Wholesale & retail | 1998 |
| J Cafferkey Pipelines Ltd | Construction | 2015 |
| J D Woodward Consulting Ltd | Professional & scientific | 2022 |
| J E Property Service Limited | Real estate | 2018 |
| J Larkin Entertainment Ltd | Construction | 2019 |
| J Newton & Co Ltd | Wholesale & retail | 2025 |
| J Swiezy Ltd | Wholesale & retail | 2024 |
| J Waldron Trading Limited | Wholesale & retail | 2007 |
| J&Hw Consulting Limited | Professional & scientific | 2018 |