| Iconic Landscapes Services Ltd | Administrative & support | 2023 |
| Ideal Electrical Systems Ltd | Construction | 2020 |
| Idency Limited | Information & communication | 2014 |
| Iebba Restaurant Limited | Hospitality | 2019 |
| IF Agri Investco Limited | Professional & scientific | 2023 |
| Ignition Technology Group Limited | Information & communication | 2018 |
| Ignition Technology Ltd | Wholesale & retail | 2015 |
| IGO REC Ltd | Administrative & support | 2023 |
| II Logistics Limited | Transport & logistics | 2014 |
| IJ Logistics Ltd | Transport & logistics | 2026 |
| IKRA02 Limited | Hospitality | 2025 |
| IL Portico Limited | Hospitality | 2011 |
| Ilkari UK Ltd | Information & communication | 2023 |
| Illingworth Research Group Limited | Health & social care | 1998 |
| Ilmdean Court Management Company Limited | Real estate | 2016 |
| ILR-00 UK Ltd | Construction | 2023 |
| Impact HGV Recovery Ltd | Transport & logistics | 2024 |
| Imperial Catering Supplies Limited | Professional & scientific | 1981 |
| Imports by Design Limited | Manufacturing | 2014 |
| Imprint Colour Ltd | Administrative & support | 2008 |
| Improve With Luke Ltd | Education | 2019 |
| IMW Ltd. | Construction | 2017 |
| IN Motion Solutions Limited | Education | 2015 |
| IN Pawsuit of Happiness Ltd | Other services | 2024 |
| Indian Taste Foods UK Limited | Wholesale & retail | 2023 |
| Indrisec Ltd | Administrative & support | 2017 |
| Infinity Electricity Ltd. | Construction | 2009 |
| Inflexion Leadership Development Ltd | Professional & scientific | 2024 |
| Information Directory Limited | Extraterritorial | 2004 |
| Ingo Ltd | Administrative & support | 2022 |
| Injector Pulling & Thread Specialist Ltd | Wholesale & retail | 2014 |
| INK Music Limited | Information & communication | 2012 |
| Inmusic Europe Limited | Wholesale & retail | 1998 |
| Inmusic UK Development, Limited | Information & communication | 2020 |
| Innobest Limited | Real estate | 2025 |
| Innosonian Europe Limited | Health & social care | 2016 |
| Innovation Forum Publishing Limited | Professional & scientific | 2014 |
| Innovations 4 Airports Ltd | Extraterritorial | 2009 |
| Innovative Resourcing Limited | Administrative & support | 2009 |
| Inntravel Limited | Administrative & support | 1992 |
| Ins-Sure Holdings Limited | Financial services | 2001 |
| Ins-Sure Services Limited | Financial services | 2000 |
| Insights That Shine Ltd | Information & communication | 2015 |
| Integral Fire Door Services Ltd | Manufacturing | 2021 |
| Integrated Electronics Limited | Manufacturing | 1961 |
| Inteleqt & Intuition Ltd | Information & communication | 2013 |
| Intellihaus Ltd | Extraterritorial | 2018 |
| Intercessions Limited | Information & communication | 1998 |
| Interchange Research IRL Limited | Professional & scientific | 2026 |
| Interchange Resources Limited | Professional & scientific | 1998 |
| Internal Alterations Ltd | Construction | 2024 |
| International Jetclub Limited | Transport & logistics | 1998 |
| International Project Management Consultants Ltd | Professional & scientific | 2015 |
| Intirity International Limited | Information & communication | 2009 |
| Intrinsic House Limited | Financial services | 2009 |
| Intuitive Solutions Limited | Information & communication | 1991 |
| Inventrite Ltd | Manufacturing | 2025 |
| Invest and Grow Projects Ltd | Professional & scientific | 2018 |
| Invhgroup Ltd | Professional & scientific | 2022 |
| Invincible Trade Frames Ltd | Wholesale & retail | 2020 |
| Invite Designs Ltd | Wholesale & retail | 2011 |
| Invivo UK Ltd | Extraterritorial | 2000 |
| Inwood Consulting Limited | Professional & scientific | 2025 |
| ION Design Limited | Information & communication | 2001 |
| Iosifdan Surveys Ltd | Professional & scientific | 2019 |
| IP Removals & Builders Ltd | Construction | 2026 |
| Iprintanything Ltd | Manufacturing | 2017 |
| IQ EP Limited | Financial services | 2023 |
| Iqqs Limited | Professional & scientific | 2012 |
| Iridium Legal Recruitment Limited | Administrative & support | 2024 |
| Irock School of Music Ltd | Arts & recreation | 2016 |
| Iron Collectables Limited | Wholesale & retail | 2025 |
| Ironfab Ltd | Manufacturing | 2025 |
| Ironing Fairy Ltd | Other services | 2016 |
| Ironman 2019 Ltd | Financial services | 2020 |
| IS Aviation Ltd | Manufacturing | 2019 |
| Isah Sustainable Farming Ltd | Agriculture & fishing | 2022 |
| Italy Co Holding Limited | Financial services | 2022 |
| Itinerary Limited | Administrative & support | 1988 |
| Itpc Consultants Ltd | Information & communication | 2014 |
| Itsallagame Ltd. | Information & communication | 2016 |
| Iventa Trade Ltd | Hospitality | 2023 |
| IZD Investments Ltd | Real estate | 2022 |
| Izzi Richardson Performing Arts Ltd | Arts & recreation | 2022 |
| J & C Automotive Limited | Other services | 2012 |
| J & C Property Investment Limited | Real estate | 2022 |
| J & C Restoration Ltd | Wholesale & retail | 2013 |
| J & G Homeshare Limited | Real estate | 2026 |
| J & J Kelly Ltd | Professional & scientific | 2013 |
| J & J Mechanical Limited | Construction | 2023 |
| J & S B Design Ltd | Construction | 2016 |
| J Lamb Consulting Group Ltd | Information & communication | 2026 |
| J Murphy Property Services Ltd | Construction | 2024 |
| J Murphy Roofing & Property Ltd | Construction | 2026 |
| J S Roofing Specialists Ltd | Construction | 2009 |
| J S Searle Properties Limited | Real estate | 2019 |
| J T Fascias Limited | Manufacturing | 2013 |
| J W Roofing & Building Services Limited | Construction | 2026 |
| J W Tropical Treats Ltd | Wholesale & retail | 2025 |
| J&E Goods Ltd | Wholesale & retail | 2025 |