| Inform Ventures Limited | Financial services | 2025 |
| Informatica Cambridge Ltd | Information & communication | 2013 |
| Informatics Unlimited Ltd | Information & communication | 2013 |
| Information Corporation Ltd | Information & communication | 2026 |
| Information for Management Limited | Professional & scientific | 2023 |
| Information in Images Limited | Professional & scientific | 2013 |
| Information Transfer Limited | Extraterritorial | 2012 |
| Informetis Europe Limited | Manufacturing | 2014 |
| Infosition Ltd. | Information & communication | 1998 |
| Inframind Labs Ltd | Information & communication | 2023 |
| Infusion Physical Theatre CIC | Arts & recreation | 2025 |
| Infusive Asset Management Limited | Administrative & support | 2014 |
| Infutech Limited | Wholesale & retail | 2007 |
| Ingenum Systems Ltd | Information & communication | 2015 |
| Ingram . Kaifeng International Ecological Engineering Co., Ltd | Wholesale & retail | 2023 |
| Ingrid Richardson Consultancy Limited | Professional & scientific | 2009 |
| Inheritance Legal Services Limited | Professional & scientific | 2010 |
| Inhouse IP Ltd | Professional & scientific | 2017 |
| Inivata Limited | Professional & scientific | 2014 |
| Inivatech Limited | Information & communication | 2005 |
| Injury Active Clinic Limited | Health & social care | 2015 |
| INK Estates Ltd | Real estate | 2021 |
| INK IT Right PMU Training Ltd | Education | 2024 |
| INK Matters Limited | Manufacturing | 2016 |
| INK Models International Ltd | Manufacturing | 2015 |
| Inkle Ltd | Information & communication | 2011 |
| Inkling Consulting Ltd | Extraterritorial | 2013 |
| Inkodo Ltd | Professional & scientific | 2017 |
| Inktop Ltd | Professional & scientific | 2021 |
| Innate Consultants Ltd | Information & communication | 2015 |
| Innate Estates Limited | Real estate | 2024 |
| Inndeavor UK Ltd | Real estate | 2025 |
| Innerlight Collective Ltd | Professional & scientific | 2025 |
| Inno Build Ltd | Construction | 2016 |
| Innoccam Ltd | Professional & scientific | 2025 |
| Innofrugal UK Ltd | Professional & scientific | 2025 |
| Innomatica Limited | Professional & scientific | 2006 |
| Innosleep Ltd | Extraterritorial | 2017 |
| Innotec Holdings Co., Ltd | Wholesale & retail | 2017 |
| Innotechai Limited | Information & communication | 2026 |
| Innotronic Solutions Ltd | Professional & scientific | 2021 |
| Innova Biosciences Ltd | Manufacturing | 2002 |
| Innovador Limited | Professional & scientific | 2018 |
| Innovate Cambridge Ltd | Professional & scientific | 2020 |
| Innovation Boat Investment Ltd | Financial services | 2022 |
| Innovation Drive Limited | Financial services | 2017 |
| Innovative Products Limited | Extraterritorial | 2009 |
| Innovensys Limited | Professional & scientific | 2000 |
| Innovia Technology Limited | Professional & scientific | 1999 |
| Innovis Search Limited | Administrative & support | 2024 |
| Innovo ACC Ltd | Professional & scientific | 2016 |
| Innovo HR Ltd | Administrative & support | 2023 |
| Innovo Tax Ltd | Administrative & support | 2016 |
| Innovosity Limited | Professional & scientific | 2016 |
| Innvo-Gen Limited | Professional & scientific | 2019 |
| INO Racing LLP | | 2022 |
| Inod International Limited | Extraterritorial | 2022 |
| Inoptec Limited | Administrative & support | 2011 |
| Inorss (UK) Technology Limited | Manufacturing | 2026 |
| Inotec AMD Limited | Professional & scientific | 2003 |
| Inputdynamics Ltd | Information & communication | 2006 |
| Inquisit Ltd | Professional & scientific | 2015 |
| Inrify Ltd | Real estate | 2024 |
| Insane Laban Limited | Manufacturing | 2026 |
| Insect Bioconversion Association Limited | Professional & scientific | 2024 |
| Insensor Ltd | Professional & scientific | 2018 |
| Inshangman Trade Andinvestment Co.. Ltd | Wholesale & retail | 2024 |
| Insight by Numbers Limited | Administrative & support | 2016 |
| Insight Regulatory Consulting Ltd. | Professional & scientific | 2013 |
| Insight Regulatory LLP | | 2018 |
| Insight Technology Search Limited | Administrative & support | 2023 |
| Insight View Limited | Real estate | 2022 |
| Insightful Marketing & Research Ltd | Professional & scientific | 2015 |
| Insignia IP Services Limited | Professional & scientific | 2009 |
| Insignis Asset Management Limited | Information & communication | 2015 |
| Insiida Electrical Technology Co., Ltd | Manufacturing | 2023 |
| Insmed Innovation UK Ltd | Professional & scientific | 2017 |
| Inspection and Engineering Services Ltd | Construction | 2010 |
| Inspiracion Consulting Limited | Information & communication | 2009 |
| Inspiramus Education Limited | Education | 2024 |
| Inspire Carpentry and Construction Ltd | Manufacturing | 2018 |
| Inspire Lettings Ltd | Real estate | 2023 |
| Inspire Properties (Cambridge) Limited | Real estate | 2020 |
| Inspired Educational Consulting Limited | Education | 2025 |
| Inspired Gardens Limited | Administrative & support | 2007 |
| Inspired Health & Fitness Club Limited | Health & social care | 2015 |
| Inspiyer Ltd | Professional & scientific | 2017 |
| Instantclean Ltd | Administrative & support | 2025 |
| Instep Adventures Ltd | Administrative & support | 2022 |
| Instratom Limited | Professional & scientific | 2022 |
| Intact Digital, Limited | Information & communication | 2016 |
| Inteachan Technologies Limited | Information & communication | 2014 |
| Integral Security Ltd | Administrative & support | 1983 |
| Integrated Communication Systems Limited | Information & communication | 1990 |
| Integrated Crop Management (SW) Limited | Agriculture & fishing | 1999 |
| Integrated IT Consultancy Ltd | Information & communication | 2014 |
| Integrated Physics Ltd | Professional & scientific | 2004 |
| Integrated Resources Ltd | Administrative & support | 2001 |
| Integre Ltd. | Professional & scientific | 2024 |
| Integrity Project Solutions Limited | Information & communication | 2018 |