| Inspired Strategic Consulting Ltd | Information & communication | 2010 |
| Inspiring Imaginations Ltd | Education | 2022 |
| Inspiros Project Solutions Limited | Other services | 2016 |
| Instant Impact Marketing Ltd | Professional & scientific | 2020 |
| Instant Protect Limited | Construction | 2010 |
| Instashopapp Ltd | Information & communication | 2024 |
| Instrumental Arts Ltd | Education | 2026 |
| Insulation Services (Anglia) Limited | Manufacturing | 1981 |
| Insurance Service Centre Limited(The) | Extraterritorial | 1985 |
| Insurance Surveys Limited | Professional & scientific | 2011 |
| Insurindex Limited | Administrative & support | 2021 |
| Intabeauty Ltd | Professional & scientific | 2026 |
| Integer Private Finance Limited | Financial services | 2015 |
| Integgra Ltd | Information & communication | 2024 |
| INTEGR8 Interiors Ltd | Construction | 2017 |
| Integra Aerospace Limited | Information & communication | 2014 |
| Integra Recruitment Ltd | Administrative & support | 2015 |
| Integral Pharma Solutions Ltd | Professional & scientific | 2024 |
| Integrated Cleaning Services Limited | Administrative & support | 1998 |
| Integrated Control Solutions (Eastern) Limited | Construction | 2001 |
| Integrated Financial Aims Limited | Financial services | 2016 |
| Integrated Security Installations Ltd | Administrative & support | 2016 |
| Integrity Fitness Education Ltd | Education | 2021 |
| Integro Languages Ltd | Professional & scientific | 2011 |
| Intelligent Charging Limited | Manufacturing | 1996 |
| Intelligent Lock & Safe Limited | Wholesale & retail | 2019 |
| Intelligent Marmalade Ltd | Information & communication | 2025 |
| Intellirad Limited | Health & social care | 2018 |
| Intellisense Ltd | Information & communication | 2026 |
| Intellixus Ltd | Health & social care | 2018 |
| Inter Group Insurance Services Limited | Extraterritorial | 1992 |
| Inter Regional Public Relations Limited | Professional & scientific | 1963 |
| Inter-Logic Norfolk Limited | Administrative & support | 2015 |
| Interactive Dimension Limited | Administrative & support | 1995 |
| Intercepter Drain Services Ltd | Manufacturing | 2014 |
| Interconnect Consulting Ltd | Professional & scientific | 2019 |
| Intercounty Plumbing & Heating Limited | Construction | 2017 |
| Interface Associates UK Limited | Education | 2011 |
| Interface Enterprises Limited | Public administration | 2012 |
| Interface IT Consultancy Limited | Information & communication | 2013 |
| Intergen Consultancy Ltd | Professional & scientific | 2022 |
| Intergroup Assistance Services Limited | Extraterritorial | 1997 |
| Interior Imports Group Limited | Wholesale & retail | 2015 |
| Interior Universe Ltd | Professional & scientific | 2022 |
| Intermediary Ltd | Manufacturing | 2020 |
| International Academy of Xunzhen Meridian Palpation Therapeutics Limited | Education | 2024 |
| International Aviation Academy-Norwich Ltd | Education | 2015 |
| International Food Market Ltd | Wholesale & retail | 2016 |
| International Grocery Store Ltd | Wholesale & retail | 2025 |
| International Maritime Asset Consult Ltd | Professional & scientific | 2018 |
| International Packaging Press Organisation | Other services | 2025 |
| International Payment Solutions (UK) Limited | Information & communication | 2023 |
| International School of Aerospace NDT Limited | Professional & scientific | 1995 |
| International Study Programmes Limited | Education | 1982 |
| International Supermarket Norwich Ltd | Wholesale & retail | 2021 |
| International Talent Limited | Information & communication | 2007 |
| International Travel Photography Ltd | Professional & scientific | 2019 |
| Interpreting Solutions Limited | Professional & scientific | 2010 |
| Intershoring Limited | Administrative & support | 2011 |
| Intertid Ltd | Hospitality | 2018 |
| Into the Gift Box Ltd | Wholesale & retail | 2021 |
| Into the Poke-Abyss Limited | Wholesale & retail | 2026 |
| Into UEA LLP | | 2007 |
| Intouch Systems Limited | Extraterritorial | 2020 |
| Intral Europe Limited | Transport & logistics | 2019 |
| Intrepid Star Limited | Professional & scientific | 2005 |
| Intricate Developments Ltd. | Real estate | 2021 |
| Intuition Logic Limited | Financial services | 2025 |
| Intwood Analytics Limited | Professional & scientific | 2009 |
| Intwood Properties Limited | Real estate | 2015 |
| Intwood Property Rentals Limited | Real estate | 2018 |
| Intwood Science Ltd | Professional & scientific | 2024 |
| Inventorize Limited | Information & communication | 1996 |
| Inverness Garage Limited | Wholesale & retail | 1972 |
| Investing Ethically Ltd | Financial services | 2000 |
| Investment Expectations Limited | Real estate | 2006 |
| Investment Trends Limited | Information & communication | 2014 |
| Investors for Purpose Limited | Financial services | 2020 |
| Investri Ltd | Wholesale & retail | 2016 |
| Invidia Hair Ltd | Other services | 2018 |
| Invidia Voices Limited | Arts & recreation | 2012 |
| Invincible Aesthetics Ltd | Other services | 2026 |
| Invisible Touch Bookkeeping Ltd | Professional & scientific | 2022 |
| Invoke Digital Ltd | Construction | 2017 |
| Invoke Digital Signage Ltd | Extraterritorial | 2018 |
| Ioannis Dimopoulos Ltd | Health & social care | 2020 |
| Iosif Zafeiropoulos Ltd | Health & social care | 2023 |
| IOT Technologies Nominees Ltd | Professional & scientific | 2023 |
| Ip-Bid Limited | Professional & scientific | 2008 |
| Iprojectsuccess Ltd | Professional & scientific | 2016 |
| IPS Dempsey Ltd | Construction | 2025 |
| Ipswich Bridalwear Ltd | Wholesale & retail | 2021 |
| Ipswich Corporation Transport Ltd | Transport & logistics | 2009 |
| Ipswich Property Services Ltd | Real estate | 2021 |
| IQ Construction Solutions Ltd | Professional & scientific | 2024 |
| IQS Security Limited | Administrative & support | 2014 |
| IR35 Shield Limited | Information & communication | 2018 |
| Irakoze-Jaros Ltd | Professional & scientific | 2019 |
| Irecharge Limited | Construction | 2021 |
| Iremovals UK Ltd | Transport & logistics | 2013 |