| I & M Corporates Ltd | Wholesale & retail | 2012 |
| I Clark Property Limited | Real estate | 2022 |
| I J J Services Limited | Agriculture & fishing | 2023 |
| I T G (GB) Limited | Real estate | 1994 |
| I&I Engineering Associates Ltd. | Professional & scientific | 2017 |
| I.D.S. Freeholds Limited | Real estate | 2020 |
| I.G.Investment Ltd | Real estate | 2010 |
| I.T. Inspection and Maintenance Ltd | Construction | 2024 |
| I4 Automation and Control Ltd | Manufacturing | 2013 |
| IAN Holdan Limited | Extraterritorial | 2002 |
| IAN Leach Safety Services Limited | Public administration | 2016 |
| IAN Robinson Bloodstock Limited | Agriculture & fishing | 2002 |
| IAN Sherburn Limited | Professional & scientific | 2012 |
| IAN Taylor Services Limited | Construction | 2016 |
| IAN V Event Services Ltd | Other services | 2018 |
| IAN Ward Services Ltd | Agriculture & fishing | 2021 |
| IAN Woodhead Limited | Wholesale & retail | 2002 |
| Ian's Fish Limited | Wholesale & retail | 2012 |
| Ianis and ADI Transport Ltd | Transport & logistics | 2023 |
| Ibishaq Limited | Health & social care | 2024 |
| Ibwest Security Services Limited | Other services | 1985 |
| Ice Systems Limited | Wholesale & retail | 2010 |
| Ice-Group Grimsby Limited | Wholesale & retail | 2016 |
| Icebrit Limited | Professional & scientific | 1993 |
| Iced Co (UK) Ltd | Arts & recreation | 2014 |
| Icing Cabin Limited | Manufacturing | 2009 |
| Icing on the Bake Ltd | Manufacturing | 2025 |
| Iconic Creative Media Ltd | Information & communication | 2013 |
| Icpa Global Limited | Information & communication | 2022 |
| ID Architecture Limited | Professional & scientific | 2010 |
| ID Developments (Lincolnshire) Limited | Real estate | 2018 |
| IDA PL Ltd | Transport & logistics | 2022 |
| Ideal Cadence Limited | Information & communication | 2014 |
| Idjassociates Limited | Professional & scientific | 2012 |
| Idol Nails & Beauty Limited | Other services | 2022 |
| Idyllic Estates Limited | Construction | 2014 |
| Iesj Limited | Wholesale & retail | 2019 |
| Ifix Fones Ltd | Wholesale & retail | 2025 |
| IHM Endoscopy Ltd | Health & social care | 2024 |
| IHM Investments Ltd | Real estate | 2022 |
| IHM Surgical Limited | Health & social care | 2021 |
| IIE Management Limited | Real estate | 2006 |
| IJS Commercial Limited | Wholesale & retail | 2012 |
| IKS Stores Ltd | Wholesale & retail | 2020 |
| Iliffe & Melhuish Ltd | Construction | 2019 |
| IM Natural Sports Services Limited | Construction | 2023 |
| IMA Elena Ltd | Transport & logistics | 2022 |
| Image School Art Exhibitions Unlimited | Wholesale & retail | 2006 |
| Imagination Enterprises Limited | Information & communication | 2013 |
| Imagineering Limited | Mining & quarrying | 2007 |
| IMC Pro Solutions Ltd | Education | 2017 |
| IMF Properties Limited | Households | 2020 |
| Immingham Industrial Estates Limited | Transport & logistics | 1973 |
| Immingham Lashing & Securing Limited | Other services | 2005 |
| Impact-Business Health & Wellbeing Limited | Professional & scientific | 2018 |
| Impcon Limited | Other services | 1990 |
| Imperial Crescent Limited | Construction | 2016 |
| Imperial Crescent Management Company Limited | Households | 2018 |
| Imperial Resin Coatings Ltd | Other services | 2001 |
| Implantology Orthodontics and Facial Aesthetics Practice Limited | Health & social care | 2026 |
| IMS (2007) Ltd | Professional & scientific | 2013 |
| IMS Flooring Limited | Extraterritorial | 2021 |
| IN Love WE Grow Limited | Wholesale & retail | 2024 |
| In-House Crusher Hire Limited | Administrative & support | 2020 |
| IN2ACHIEVE Ltd | Education | 2015 |
| Inc Labs Limited | Professional & scientific | 2025 |
| Incisive Recruitment Limited | Administrative & support | 2011 |
| Incredible Ice Cream Ltd | Wholesale & retail | 2018 |
| Independent Shipping Agencies Limited | Transport & logistics | 2006 |
| Indigo Sales Performance Ltd | Administrative & support | 2017 |
| Individual Differences Ltd | Administrative & support | 2019 |
| Industrial Control & Software Limited | Professional & scientific | 2026 |
| Industrial Drying Systems Limited | Real estate | 1993 |
| Industrial Engines Limited | Wholesale & retail | 2020 |
| Industrial Medical Agency Limited | Professional & scientific | 2008 |
| Industrial Site Services Limited | Manufacturing | 2017 |
| Industrix Plumbing & Joinery Limited | Construction | 2026 |
| Infinite Care (Lincs) Limited | Health & social care | 2003 |
| Infinity Coves Ltd | Construction | 2014 |
| Ingoldby Limited | Wholesale & retail | 2024 |
| Ings Consultants Ltd | Professional & scientific | 2023 |
| Initiatives for Nursing Research Limited | Professional & scientific | 2025 |
| Inline Access Limited | Construction | 2025 |
| Inn Pubs Ltd | Hospitality | 2016 |
| INNOV8 Consultancy Ltd | Professional & scientific | 2018 |
| Innova Consultancy Limited | Professional & scientific | 2017 |
| Innovateapi Limited | Information & communication | 2018 |
| Innovation Software Consultants Limited | Information & communication | 2001 |
| INS Property Investment Ltd | Real estate | 2019 |
| Insight Hypnotherapy Limited | Health & social care | 2015 |
| Inspire Community Activities Louth Community Interest Company | Education | 2025 |
| Inspire Global Learning Limited | Education | 2016 |
| Inspired Property Hub Limited | Real estate | 2018 |
| Insta Shell Limited | Manufacturing | 2025 |
| Instant Cash Limited | Wholesale & retail | 2023 |
| Instropro Limited | Professional & scientific | 2012 |
| Instyle Groundworks Ltd | Construction | 2018 |
| INT Building & Maintenance Services Ltd | Construction | 2026 |
| Intelligence Project Management Limited | Information & communication | 2019 |
| Intelligent Trust Recruitment Limited | Administrative & support | 2006 |