| Ibiza Executive Service Ltd | Professional & scientific | 2006 |
| ICB Inns Ltd | Hospitality | 2024 |
| Icbs Educational Consultants Ltd | Education | 2026 |
| ICC Hemel Ltd | Administrative & support | 2024 |
| Icraft Group Ltd | Wholesale & retail | 2025 |
| ID Integrated Security Limited | Administrative & support | 2008 |
| ID Logistic Ltd | Transport & logistics | 2022 |
| ID8 Media Ltd | Information & communication | 2026 |
| Ideal Market Limited | Wholesale & retail | 2024 |
| Idfa Ltd | Financial services | 2021 |
| IDI Events Ltd | Administrative & support | 2025 |
| Idiotlamp Productions Limited | Information & communication | 2005 |
| IDM Construct Ltd | Construction | 2026 |
| IFA Pole & Aerial Ltd | Health & social care | 2016 |
| IFD Construction Limited | Construction | 2021 |
| Ifeco-Vim Limited | Information & communication | 2016 |
| Ifenties Ltd | Health & social care | 2014 |
| IFY Consults Ltd | Professional & scientific | 2022 |
| Igas Heating Limited | Construction | 2016 |
| Igbo Community Luton | Other services | 2018 |
| Ignis Care Limited | Administrative & support | 2024 |
| Ignite Insight Brokers Ltd | Professional & scientific | 2019 |
| Ignition Growth Ltd | Administrative & support | 2023 |
| Ignition Human Performance Ltd | Professional & scientific | 2016 |
| Iguana Creative Services Limited | Administrative & support | 1996 |
| Ihaz Ltd | Wholesale & retail | 2018 |
| IHD-2012 Ltd | Other services | 2012 |
| Ihome Creative Ltd | Construction | 2017 |
| IHR Construction and Development Limited | Construction | 2024 |
| IJB Engineering Limited | Manufacturing | 2019 |
| Ikdl Ltd | Information & communication | 2024 |
| IKL Living Limited | Hospitality | 2025 |
| Ikya IT Solutions Ltd | Information & communication | 2021 |
| Ikya Properties Ltd | Real estate | 2022 |
| Iliminate Limited | Other services | 2025 |
| Illumaglaze Ltd | Manufacturing | 2025 |
| IMA (Property) Management Company Limited | Households | 2014 |
| IMA Mortgages & Protection Ltd | Financial services | 2010 |
| Image Carpentry and Construction Ltd | Construction | 2019 |
| Imagexchange Grooming Chambers Limited | Professional & scientific | 2022 |
| Imagination 360 Ltd | Wholesale & retail | 2022 |
| Imagine Executive Solutions Ltd | Administrative & support | 2025 |
| Imagine Food Ltd | Hospitality | 2018 |
| Imagine International Group Ltd | Wholesale & retail | 2019 |
| Imega Ltd | Information & communication | 2022 |
| Imerchants Limited | Wholesale & retail | 2020 |
| Imhotec Ltd | Information & communication | 2018 |
| Imindu Limited | Health & social care | 2025 |
| Immanentize Ltd | Professional & scientific | 2022 |
| IMP Trans Limited | Transport & logistics | 2023 |
| Impact Consulting and Development Ltd | Education | 2025 |
| Impart.Money Limited | Information & communication | 2024 |
| Imperator Installations Ltd | Construction | 2018 |
| Imperium SDM Ltd | Real estate | 2020 |
| Imre Bartus Logistics Limited | Transport & logistics | 2017 |
| IMT Resourcing Solutions Ltd | Administrative & support | 2022 |
| Imus Iterum Capital Limited | Professional & scientific | 2016 |
| Imutlu Electrical Limited | Construction | 2024 |
| IN Car Systems Limited | Wholesale & retail | 2012 |
| IN Home Property Maintenance Ltd | Manufacturing | 2017 |
| IN the Frame Photography Limited | Arts & recreation | 2013 |
| In-Excess Removals Limited | Transport & logistics | 2000 |
| In-Excess Waste Management Ltd | Water & waste | 2023 |
| Incensed Films UK Ltd. | Information & communication | 2017 |
| Independence Plumbing & Heating Ltd | Construction | 2020 |
| Independent Mortgage Associates (Property) Limited | Real estate | 2013 |
| Independent Telecommunications Consultants Limited | Information & communication | 1999 |
| Independia Ltd | Health & social care | 2023 |
| Indicro Ltd | Professional & scientific | 2023 |
| Indigo (Bath Lane) Management Company Limited | Households | 2006 |
| Indigo Food Limited | Hospitality | 2025 |
| Indigo Tree Digital Limited | Information & communication | 2011 |
| Indigopatch Limited | Information & communication | 2024 |
| Industrial and Commercial Supplies Limited | Wholesale & retail | 2020 |
| Industrial Coordination Limited | Information & communication | 2025 |
| Inel Electrical Ltd | Construction | 2024 |
| Infermiera Healthcare Ltd | Administrative & support | 2020 |
| Infinit Digital Ltd | Professional & scientific | 2024 |
| Infinite Adventures Ltd | Administrative & support | 2025 |
| Infinite Steel Solution Limited | Manufacturing | 2022 |
| Infinity Home Solutions Limited | Construction | 2018 |
| Infinity Plumbing and Heating Services Ltd | Construction | 2025 |
| Infinity Staff Global Ltd | Administrative & support | 2025 |
| Infinity Web Design Ltd | Information & communication | 2019 |
| Influx Productions Ltd | Information & communication | 2019 |
| Infornixs Ltd | Information & communication | 2026 |
| Infrascape Contracting Limited | Construction | 2012 |
| Inger Lease Limited | Information & communication | 2015 |
| Inicio Partners Executive Search Ltd | Administrative & support | 2024 |
| Inicio Partners Group Ltd | Extraterritorial | 2025 |
| Inline Plumbing and Heating Ltd | Construction | 2016 |
| Inndus UK Limited | Manufacturing | 2013 |
| INNOV8 LS Services Limited | Professional & scientific | 2024 |
| Innovate Bookkeeping Limited | Professional & scientific | 2023 |
| Innovation Advances Limited | Health & social care | 2017 |
| Innovation Media Group Ltd | Information & communication | 2025 |
| Innovation Support Group Ltd. | Construction | 2015 |
| Innovative Eco Homes Limited | Manufacturing | 2025 |
| Innovative Plasterers Limited | Construction | 2025 |
| Innovative.Ly Ltd | Information & communication | 2018 |