| Ignite My Boiler Limited | Extraterritorial | 2026 |
| IGS Dry-Wall Ltd | Construction | 2017 |
| Ihsaan Development Ltd | Professional & scientific | 2018 |
| Ihubbusiness Limited | Information & communication | 2012 |
| Iiwyk Ltd | Professional & scientific | 2025 |
| Ikies Properties Ltd | Real estate | 2025 |
| IL Capriccio Limited | Wholesale & retail | 2024 |
| Illumitec Limited | Information & communication | 2024 |
| ILO Estates Ltd | Real estate | 2024 |
| Image Internet Limited | Information & communication | 2020 |
| Imagesteps Limited | Information & communication | 2003 |
| Imagine XO Ltd | Wholesale & retail | 2022 |
| Imap Student Ltd | Construction | 2014 |
| Imogenics Haematology Services Ltd | Health & social care | 2023 |
| Impact Computer Systems Limited | Information & communication | 1995 |
| Impact Solution Services Ltd | Wholesale & retail | 2023 |
| Imperium Adderbury Limited | Real estate | 2025 |
| Imperium Construction and Development Limited | Construction | 2024 |
| Imperium SG5 4FT Ltd | Real estate | 2022 |
| Implant Training Egypt Limited | Education | 2023 |
| IN Pursuit of Better Ltd | Professional & scientific | 2025 |
| In-House Investments Limited | Real estate | 1999 |
| Incontro Ltd | Hospitality | 2019 |
| Indigo Electrics Ltd | Construction | 2021 |
| Indira EYE Care Ltd | Health & social care | 2021 |
| Indoor Maintenance Limited | Construction | 2025 |
| Infinitus IT Services Ltd | Information & communication | 2022 |
| Infinity Holiday Camps Limited | Health & social care | 2022 |
| Infinity Wines Limited | Wholesale & retail | 2015 |
| Inflection Films Limited | Other services | 2019 |
| Infomap Solutions Ltd | Information & communication | 2016 |
| Innotex Transfers Ltd | Manufacturing | 2024 |
| INNOV8 Projects Ltd | Construction | 2019 |
| Innovation Hub Services Ltd | Professional & scientific | 2020 |
| Innovation Minds Consulting Ltd | Professional & scientific | 2011 |
| Insanely Gifted Teachers Ltd | Education | 2020 |
| Insight Consulting Solutions Ltd | Administrative & support | 2024 |
| Insolum Services Limited | Wholesale & retail | 2007 |
| Inspire Day Service Limited | Health & social care | 2016 |
| Insta Products Limited | Wholesale & retail | 2026 |
| Instix UK Ltd | Information & communication | 2024 |
| Instrument Glasses,Limited | Manufacturing | 1962 |
| Intanglo Limited | Professional & scientific | 2009 |
| Intec Systems (EOT) Limited | Professional & scientific | 2022 |
| Intec Systems Limited | Information & communication | 1987 |
| Integrated Computer Controls Ltd | Information & communication | 1999 |
| Integrated Cranial Practice Limited | Health & social care | 2010 |
| Intelligent Conversation Development Limited | Information & communication | 2015 |
| Intelligent Enterprises Limited | Arts & recreation | 1996 |
| Intelligent Security & Electrical Ltd | Construction | 2021 |
| Interiors Europe Projects Ltd | Construction | 2014 |
| Interlink Trading Limited | Real estate | 1984 |
| International Business and Executive Management Ltd | Professional & scientific | 2018 |
| International Creative Agency (ICA) Ltd | Administrative & support | 2008 |
| International Services Limited | Real estate | 2016 |
| International Spill Control Organisation Ltd | Administrative & support | 2024 |
| Internet Brands Limited | Professional & scientific | 2003 |
| Internet Wizard Limited | Information & communication | 2011 |
| Interproject Enterprises LLP | | 2012 |
| Into Concerts Limited | Arts & recreation | 2014 |
| Intocoin Ltd | Real estate | 2013 |
| Inveniam Partners Limited | Professional & scientific | 2018 |
| Investment Asset Management Limited | Administrative & support | 2012 |
| Invision Property Group Limited | Real estate | 2023 |
| Ioannides Properties Ltd | Real estate | 2022 |
| Ioniq Energy Ltd | Professional & scientific | 2026 |
| Ion’S Transport Ltd | Transport & logistics | 2020 |
| IPJ Creative Ltd | Education | 2024 |
| IQ Infomedia Ltd | Information & communication | 2021 |
| Iqueue.Com Limited | Administrative & support | 2025 |
| Iron Blue Ltd | Administrative & support | 2013 |
| Iron Way Ltd | Transport & logistics | 2025 |
| Ironwood Worldwide Ltd. | Financial services | 2017 |
| IS Property Ventures Ltd | Real estate | 2026 |
| Isca Foil Limited | Professional & scientific | 2001 |
| Iskra Inter Commerce Ltd | Wholesale & retail | 2003 |
| Ismash Tech Limited | Wholesale & retail | 2024 |
| Istari Collectibles Ltd | Wholesale & retail | 2024 |
| IT Systems Recovery Limited | Information & communication | 2023 |
| It'Z a Wrap Ltd | Hospitality | 2024 |
| Italian Food at Home Ltd | Wholesale & retail | 2022 |
| Italian.It Ltd | Administrative & support | 2018 |
| Italianshowcasing by LR Ltd | Wholesale & retail | 2020 |
| ITG Creative Limited | Wholesale & retail | 2025 |
| Iulian's Transport Ltd | Transport & logistics | 2025 |
| IV an & SON Transport Limited | Transport & logistics | 2016 |
| Ivew Limited | Other services | 2023 |
| J & C Amatt Ltd | Construction | 2013 |
| J Ayinde Ltd | Information & communication | 2021 |
| J Caras Ltd | Professional & scientific | 2011 |
| J E Electrics Ltd. | Manufacturing | 2013 |
| J Floyd Consulting Limited | Professional & scientific | 2017 |
| J Ghosh Ltd | Health & social care | 2010 |
| J Goddard Home Developments Limited | Construction | 2025 |
| J J Accountancy Tax & Management Consultants Ltd | Professional & scientific | 2019 |
| J K Construction (Europe) Ltd | Construction | 2017 |
| J Kelly Plant Services Ltd | Construction | 2014 |
| J L S Consulting Limited | Professional & scientific | 2003 |
| J S Rainbow Limited | Real estate | 2010 |
| J Satwick Consulting Ltd | Real estate | 2016 |