| Hygges London Limited | Wholesale & retail | 2024 |
| Hyle Trading Co., Ltd. | Extraterritorial | 2015 |
| Hyndewood Garages Freehold Limited | Households | 2020 |
| Hyoung Hockey Co., Ltd | Extraterritorial | 2024 |
| Hypernation Fitness Ltd | Administrative & support | 2017 |
| Hyway Cleaning Limited | Administrative & support | 2017 |
| I AM an Adult Community Interest Company | Health & social care | 2020 |
| I G Humphrey Developments Limited | Real estate | 2000 |
| I-Deserved Limited | Real estate | 2010 |
| I-Group Construction Ltd | Construction | 2013 |
| I-Ship Marine Service Limited | Wholesale & retail | 2020 |
| IA Accountancy Limited | Professional & scientific | 2024 |
| Iain Green Consultancy Limited | Professional & scientific | 2026 |
| IAM Properties Rentals and Lettings Ltd | Hospitality | 2023 |
| IAN Industrial Systems Limited | Manufacturing | 2025 |
| IAN Johnson Limited | Professional & scientific | 2010 |
| Iangler Ltd | Wholesale & retail | 2010 |
| Iauss Global Limited | Extraterritorial | 2020 |
| IB Chalets Group Limited | Hospitality | 2017 |
| Ibbh Limited | Information & communication | 2020 |
| Iber Interiors Limited | Construction | 2014 |
| Ice London Aesthetics Clinic Limited | Other services | 2024 |
| Ice Tree Yard Limited | Other services | 2017 |
| Iceberg Recovery Ltd | Wholesale & retail | 2024 |
| Icehub Ltd | Professional & scientific | 2018 |
| Icepworld Ltd | Wholesale & retail | 2009 |
| ICM Elite Ltd | Professional & scientific | 2018 |
| ICM Engineering Limited | Construction | 2010 |
| ID2 Productions Limited | Administrative & support | 2013 |
| IDA International Trade Co., Ltd | Extraterritorial | 2019 |
| Ideal Cleaning Services (South East) Ltd | Administrative & support | 2009 |
| Ideals Trading Co., Ltd | Extraterritorial | 2019 |
| Identity Custom Furniture Co., Ltd | Extraterritorial | 2021 |
| Idimt Ltd | Wholesale & retail | 2024 |
| Idiomniscience Limited | Information & communication | 2012 |
| Ifix Group Limited | Wholesale & retail | 2017 |
| Ifrs 9 MK Risk Solutions Limited | Information & communication | 2018 |
| IG Giantech Ltd | Information & communication | 2022 |
| IG Humphrey Holdings Limited | Real estate | 2024 |
| IG1Z Ltd | Construction | 2018 |
| Iggy Empire Ltd | Other services | 2025 |
| Ignet Group Ltd | Wholesale & retail | 2014 |
| Ignite Games Limited | Information & communication | 2026 |
| Igreentech Garden Industry Co., Ltd | Extraterritorial | 2019 |
| Igroup Access Limited | Construction | 2024 |
| Igroup Roofing Limited | Construction | 2016 |
| IKC Bearing Co., Ltd | Professional & scientific | 2018 |
| Ikeya International Trading Ltd | Wholesale & retail | 2020 |
| Ilderton Road Developments Limited | Construction | 2023 |
| Illuminaid Ltd | Information & communication | 2024 |
| Image YW Corporation Limited | Wholesale & retail | 2019 |
| Iman DE Contactos Ltd | Information & communication | 2022 |
| Imay Industrial Co., Ltd | Extraterritorial | 2014 |
| Immortal Marine Service Company Limited | Manufacturing | 2023 |
| Imoda Limited | Extraterritorial | 2020 |
| Imoveproperty Limited | Real estate | 2011 |
| Impact Fire Limited | Professional & scientific | 2005 |
| Impact Multi Academy Trust | Education | 2011 |
| Impact Teaching Ltd | Education | 2018 |
| Imperial Auto Imports Ltd | Wholesale & retail | 2026 |
| Imperial Property Company (Norwich 3) Limited | Real estate | 2006 |
| Impet Limited | Information & communication | 2008 |
| IN House Projects Limited | Construction | 2025 |
| IN OUR Nature Productions Ltd | Information & communication | 2021 |
| IN R.E. Ltd | Professional & scientific | 2009 |
| Inai Finance Limited | Administrative & support | 2026 |
| Inastrum Limited | Professional & scientific | 2019 |
| Inbloom International Trading Co., Ltd | Extraterritorial | 2013 |
| Inborn International Group Co., Limited | Extraterritorial | 2023 |
| Incana Control Ltd | Extraterritorial | 2016 |
| Inception Creative Limited | Professional & scientific | 2018 |
| Incerval, S.L. Ltd | Professional & scientific | 2016 |
| Inchoi Holdings Limited | Manufacturing | 2026 |
| Inclusive Impact Ltd | Professional & scientific | 2021 |
| Indigo ILG Limited | Real estate | 2023 |
| Indigo Vehicle Co., Ltd. | Manufacturing | 2018 |
| Indum Limited | Manufacturing | 2021 |
| Infee Fashion Products Co., Ltd | Wholesale & retail | 2020 |
| Infinite Movement Limited | Financial services | 2024 |
| Infinite Optical Limited | Extraterritorial | 2014 |
| Ingeil International Group (UK) Limited | Extraterritorial | 2016 |
| Ingersoll-Rand Industrial Technologies Limited | Manufacturing | 2024 |
| Ingram Fluid Technology Co., Limited | Extraterritorial | 2012 |
| Inhom Trading Co., Ltd | Wholesale & retail | 2023 |
| Inicio Homes Limited | Construction | 2015 |
| Inicio Investments Limited | Real estate | 2020 |
| Inlier Ltd | Other services | 2019 |
| Inner Mongolia Hongte New Material Technology Co., Ltd | Wholesale & retail | 2024 |
| Inness Furniture UK Limited | Extraterritorial | 2010 |
| Inno Internaitonal Limited | Manufacturing | 2025 |
| Innoleo Ltd | Extraterritorial | 2018 |
| Innotec Worldwide Limited | Extraterritorial | 2017 |
| Innova EME Limited | Wholesale & retail | 2024 |
| Innovate Industry Ltd | Manufacturing | 2020 |
| Innovate International Co., Ltd. | Wholesale & retail | 2021 |
| Innovation Biotech (Beijing) Co., Ltd | Extraterritorial | 2009 |
| Innovative Start Point Ltd | Information & communication | 2021 |
| Innoverse Mart Ltd | Extraterritorial | 2025 |
| Inopha International Co., Limited | Extraterritorial | 2016 |
| Inpans Fast Foods Ltd | Hospitality | 2020 |