| Iannis Ltd | Transport & logistics | 2020 |
| IAW Plumbing & Heating Limited | Construction | 2021 |
| Ibcon Ltd | Construction | 2015 |
| Ice Dreaming Ltd | Wholesale & retail | 2023 |
| Ice Global Enterprises Ltd | Information & communication | 2021 |
| Ice Phoenix Trading Ltd | Administrative & support | 2025 |
| Icenorth Limited | Transport & logistics | 1984 |
| Ichiko Bento Ltd | Administrative & support | 2017 |
| ICM Testing Limited | Information & communication | 2017 |
| Icol Limited | Real estate | 1953 |
| Iconfirm Privacy UK Limited | Information & communication | 2017 |
| Iconic Padel Ltd | Arts & recreation | 2025 |
| Iconic Velocity Group Ltd | Wholesale & retail | 2025 |
| ID Domestic Ltd | Administrative & support | 2026 |
| Idbi Living Limited | Construction | 2025 |
| Idbi Solutions Limited | Information & communication | 2016 |
| Iddy Biddy Ltd | Manufacturing | 2025 |
| Identity Agency Limited | Professional & scientific | 2021 |
| IDK Commerce Ltd | Wholesale & retail | 2025 |
| Idle Valley View Management Company Limited | Households | 2018 |
| IDM Financial Management Advisory Services Ltd | Professional & scientific | 2020 |
| Idmskills Limited | Professional & scientific | 2011 |
| Idreesmomand Ltd | Wholesale & retail | 2026 |
| IE Building Services Ltd | Construction | 2021 |
| IES Medical Services Ltd | Manufacturing | 2011 |
| IES Property Investments Ltd | Real estate | 2020 |
| IES UK Holdings Ltd | Financial services | 2020 |
| IES UK Limited | Construction | 2006 |
| IFI Group Holding Company Ltd | Agriculture & fishing | 2024 |
| IFI Group Ltd | Public administration | 2017 |
| Ifrandwia Ltd | Real estate | 2022 |
| Igas Energy Development Limited | Mining & quarrying | 2010 |
| Igas Energy Enterprise Limited | Mining & quarrying | 2005 |
| Igas Energy Limited | Mining & quarrying | 2004 |
| IGD Engineering Services Limited | Professional & scientific | 2006 |
| IGL HDD Limited | Construction | 2024 |
| Igluu Ltd | Wholesale & retail | 2016 |
| Ignite Education AI Limited | Education | 2024 |
| Ignite Education Ltd | Education | 2016 |
| Ignite Growth Consultancy Ltd | Professional & scientific | 2019 |
| IGS GAS (Industrial GAS Services) Limited | Manufacturing | 2014 |
| IH Legal Consultancy Ltd | Professional & scientific | 2025 |
| Ihoneyfield Ltd | Arts & recreation | 2023 |
| IJB Property Developing Company Limited | Real estate | 2008 |
| IJB Property Investment Ltd | Real estate | 2014 |
| Ik&W Properties Limited | Real estate | 1975 |
| Ilarch Limited | Wholesale & retail | 2020 |
| Ilkeston Rentals Limited | Real estate | 2015 |
| Illsley Holdings (Lincoln) Limited | Financial services | 2019 |
| Illuminated Consultancies Limited | Administrative & support | 2025 |
| Ilott Management Services Ltd | Professional & scientific | 2016 |
| Imagen Technology Ltd | Information & communication | 2010 |
| Imagenation Lincoln Limited | Professional & scientific | 2018 |
| Imagevision.Ai UK Ltd | Information & communication | 2026 |
| Imagine Smith Ltd | Arts & recreation | 2018 |
| IMB Race Clothing Limited | Wholesale & retail | 2025 |
| Imisir Medical Ltd | Health & social care | 2023 |
| IMJ Retail Consultancy Ltd | Professional & scientific | 2023 |
| IMP & Maker Holdings Ltd | Financial services | 2022 |
| IMP & Maker Ltd | Manufacturing | 2020 |
| IMP Building Services Ltd | Construction | 2024 |
| IMP Conservation Limited | Construction | 2000 |
| IMP Electrical Ltd | Construction | 2022 |
| IMP GAS Supplies Ltd | Wholesale & retail | 2021 |
| IMP Healthcare Limited | Health & social care | 2015 |
| IMP Heating Limited | Manufacturing | 2011 |
| IMP Home Surveying Ltd | Construction | 2023 |
| IMP Pave Limited | Administrative & support | 2015 |
| IMP Property Ltd | Real estate | 2017 |
| IMP Scaffolding Lincoln Ltd | Construction | 2023 |
| IMP Scaffolding Ltd | Construction | 2019 |
| IMP Trading Lincoln Ltd | Wholesale & retail | 2021 |
| Impact Contracting Solutions Limited | Administrative & support | 2015 |
| Impact Employment Law Limited | Professional & scientific | 2026 |
| Impact Engineering Services Limited | Construction | 2002 |
| Impact Managed Services Limited | Information & communication | 2024 |
| Impact Recruitment Solutions Limited | Administrative & support | 2013 |
| Impart Investments Limited | Financial services | 2023 |
| Impdustrial Ltd | Wholesale & retail | 2022 |
| Imperial Machine Company Limited | Manufacturing | 1917 |
| Imperium Aeternum Corporation Ltd | Real estate | 2026 |
| Imperium Air Conditioning Limited | Professional & scientific | 2025 |
| Impfinity Ltd | Administrative & support | 2017 |
| Impi Book Ltd | Wholesale & retail | 2024 |
| Impress Barber Ltd | Other services | 2023 |
| Imprint Colour Printers Limited | Manufacturing | 1995 |
| Imprint Wrightsway Limited | Professional & scientific | 2001 |
| Imps (UK) Ltd | Professional & scientific | 2012 |
| Imps Maintenance Engineering Ltd | Professional & scientific | 2018 |
| Imps Rest Ltd | Hospitality | 2024 |
| Impsgaming Ltd. | Wholesale & retail | 2016 |
| Impware Ltd | Information & communication | 2025 |
| Imran Mushtaq Ltd | Health & social care | 2012 |
| IN 2 Food Innovation Ltd | Other services | 2017 |
| In-House (PBS) Limited | Professional & scientific | 2015 |
| In-House CAD Ltd | Information & communication | 2019 |
| Inca 571 Property Ltd | Real estate | 2026 |
| Incar (Lincoln) Limited | Wholesale & retail | 2010 |
| Incitatio Limited | Wholesale & retail | 2024 |
| Inclusion 21 Centre Ltd | Health & social care | 2020 |