| Imperial Tobacco Overseas Limited | Financial services | 1903 |
| Imperial Tobacco Pension Trustees (Burlington House) Limited | Real estate | 2002 |
| Imperial Tobacco Pension Trustees Limited | Financial services | 1929 |
| Imperial Tobacco US Holdings B.V. | | 2021 |
| Imperial Tobacco Ventures Limited | Wholesale & retail | 2017 |
| Imperial Windows & Conservatories (Bristol) Limited | Manufacturing | 2021 |
| Imperial Windows and Conservatories Limited | Manufacturing | 2006 |
| Imperium Business Solutions Limited | Professional & scientific | 2007 |
| Impermanence Dance Theatre | Arts & recreation | 2014 |
| Impetus Legal Limited | Professional & scientific | 2024 |
| Impinj UK Limited | Information & communication | 2015 |
| Implement One Limited | Information & communication | 2021 |
| Import Export Services (GRP) Limited | Manufacturing | 2010 |
| Import Export Services Ltd | Manufacturing | 2001 |
| Importance Records Ltd | Information & communication | 2025 |
| Impossible Trading Ltd | Wholesale & retail | 2022 |
| Imprints Music Ltd | Arts & recreation | 2021 |
| Improgresso Ltd | Professional & scientific | 2014 |
| Improved Financial Solutions Limited | Extraterritorial | 2003 |
| Improvement House Ltd | Administrative & support | 2013 |
| Improving Prospects Ltd | Health & social care | 2009 |
| Impulsonics Ltd | Professional & scientific | 2023 |
| Imranmrd Ltd | Hospitality | 2022 |
| IMS Consulting Europe Ltd | Professional & scientific | 2003 |
| Imsco Limited | Information & communication | 2018 |
| IMX Ltd | Construction | 2025 |
| IMX Software Group Limited | Information & communication | 2014 |
| IMX Software UK Limited | Information & communication | 2001 |
| IN Bristol Limited | Arts & recreation | 2006 |
| IN Depth Film & Media Productions Limited | Information & communication | 2025 |
| IN Faith Care Ltd | Health & social care | 2019 |
| IN Faith Care Solutions Ltd | Real estate | 2025 |
| IN House Building Design Limited | Professional & scientific | 2003 |
| IN House Supported Accommodation Ltd | Hospitality | 2024 |
| IN Pictures Limited | Arts & recreation | 2009 |
| IN Progress Engineering (IPL) Ltd | Manufacturing | 1992 |
| IN Rhythm Living Ltd | Real estate | 2023 |
| IN Step Paraplanning Ltd | Administrative & support | 2023 |
| IN the Meantime Limited | Arts & recreation | 2010 |
| IN the MIX Introductions Limited | Other services | 2014 |
| IN the Presence of Love C.I.C. | Hospitality | 2020 |
| IN Veritate Ltd | Professional & scientific | 2009 |
| IN VIA Lactea Ltd | Hospitality | 2021 |
| In(F)Inite Records UK C.I.C. | Information & communication | 2024 |
| In-House Research Global Ltd | Professional & scientific | 2017 |
| In-Touch Talent Group Limited | Arts & recreation | 2026 |
| Inaata Ltd | Other services | 2022 |
| Inaca UK Limited | Administrative & support | 2012 |
| Inalignment Living Limited | Real estate | 2023 |
| Inarc Limited | Professional & scientific | 2012 |
| Inaro Limited | Health & social care | 2023 |
| Inature Limited | Wholesale & retail | 2023 |
| INB Terminals Infrastructure (NI) Ltd. | Transport & logistics | 2016 |
| Inba Trans Ltd | Transport & logistics | 2021 |
| Inbiuro Ltd | Professional & scientific | 2019 |
| Inbroke LLP | | 2018 |
| Inca Coffee Limited | Wholesale & retail | 2012 |
| Inca Empire Limited | Wholesale & retail | 2019 |
| Incastone Landscaping Ltd | Administrative & support | 2000 |
| Incite Solutions Limited | Administrative & support | 2007 |
| Incite Technologies Group Limited | Information & communication | 2026 |
| Incline Arts Ltd | Arts & recreation | 2023 |
| Inclued Ltd | Information & communication | 2021 |
| Inclusive Change at Work C.I.C. | Professional & scientific | 2021 |
| Inclusive Change Ltd | Professional & scientific | 2020 |
| Inclusive Events SW Ltd | Arts & recreation | 2024 |
| Inclusive Futures Academy Limited | Administrative & support | 2022 |
| Inclusive Futures Coaching CIC | Education | 2020 |
| Inclusive Integrations C.I.C. | Information & communication | 2024 |
| Inclusive Learning Solutions Limited | Education | 2015 |
| Incog Properties Ltd | Administrative & support | 2024 |
| Incom Technical Solutions Ltd. | Information & communication | 2016 |
| Incore Group Limited | Real estate | 2024 |
| Incorporate UK Limited | Extraterritorial | 1998 |
| Incorporation UK Limited | Professional & scientific | 1998 |
| Incredibots CIC | Wholesale & retail | 2018 |
| Incremental Architecture Ltd | Professional & scientific | 2021 |
| Incubator Services and Sales Limited | Manufacturing | 2012 |
| Incubus Finance Limited | Financial services | 2004 |
| Incubus Limited | Professional & scientific | 2004 |
| INCUV8OR Limited | Information & communication | 2022 |
| Indaba Consulting Limited | Professional & scientific | 2021 |
| Indago Development Ltd | Professional & scientific | 2024 |
| Indago Development One Ltd | Education | 2022 |
| Indata Products Limited | Professional & scientific | 2007 |
| Indeed Care Security Ltd | Administrative & support | 2021 |
| Indeed Security Security Limited | Administrative & support | 2023 |
| Indent Design Limited | Professional & scientific | 1999 |
| Independence Support Services Ltd | Administrative & support | 2019 |
| Independent Audit Limited | Administrative & support | 2002 |
| Independent Business Centres (1LKS) Limited | Real estate | 2015 |
| Independent Business Centres (7 Unity Street) Limited | Real estate | 2015 |
| Independent Business Centres (70PS) Limited | Real estate | 2014 |
| Independent Business Centres (Managed) Limited | Real estate | 2006 |
| Independent Commercial Lets Limited | Real estate | 2025 |
| Independent Composites Limited | Manufacturing | 2006 |
| Independent Financial Advisory Service Limited | Financial services | 2006 |
| Independent Gourmet Foods (Ideal Foods) Limited | Wholesale & retail | 2007 |
| Independent Investment Analysis Limited | Financial services | 1995 |
| Independent Mobiles Ltd | Information & communication | 2003 |