| Human Consumption Productions Limited | Information & communication | 2023 |
| Humberstone Park Close Limited | Households | 2009 |
| Hungry Clearance Ltd | Wholesale & retail | 2021 |
| Hungry Olive Ltd | Hospitality | 2023 |
| Hunter Construction Group Ltd | Construction | 2026 |
| Hursley Systems Ltd | Information & communication | 2025 |
| Hyde Leadership Consultancy Ltd | Education | 2025 |
| Hynes GAS Ltd | Construction | 2010 |
| I Smyth Ltd | Professional & scientific | 2023 |
| I. a. (East MID) Ltd | Health & social care | 2010 |
| IAN Williams Electrical Limited | Construction | 2010 |
| IB Kumar Ltd | Administrative & support | 2022 |
| Ichiro Consulting Ltd | Information & communication | 2026 |
| Iconiq Innovation Ltd | Professional & scientific | 2010 |
| ICP Cleaning Services Ltd | Administrative & support | 2008 |
| ID Ology Limited | Information & communication | 1994 |
| Id-Direct Ltd | Administrative & support | 2002 |
| IDE Medical Ltd | Health & social care | 2025 |
| Image Copy Print Ltd | Manufacturing | 2026 |
| Imelda Barry Ltd | Professional & scientific | 2024 |
| Imogen Fawkes Ltd | Wholesale & retail | 2021 |
| Imperio Holdings Ltd | Professional & scientific | 2023 |
| Impex Foods (Midlands) Limited | Wholesale & retail | 2019 |
| Impex Foods (South) Limited | Wholesale & retail | 2019 |
| Impex Pro Limited | Wholesale & retail | 2019 |
| Impulse Power Limited | Construction | 2026 |
| IN House Procurement Limited | Wholesale & retail | 2013 |
| IN Property Management Limited | Real estate | 2010 |
| India 2 Mawsley Limited | Hospitality | 2011 |
| India 2M Limited | Hospitality | 2015 |
| Indigo (Midlands) Limited | Information & communication | 2002 |
| Indigo Computing Limited | Information & communication | 2004 |
| Indigo Sigma Insights Ltd | Professional & scientific | 2024 |
| Industrial Packaging Solutions Limited | Administrative & support | 2024 |
| Inferva Ltd | Information & communication | 2026 |
| Infinitra Films Ltd | Information & communication | 2025 |
| Infinity PR Limited | Professional & scientific | 2024 |
| Infonote Datasystems Limited | Information & communication | 1998 |
| Informed Consulting Limited | Professional & scientific | 2008 |
| Informed Properties Ltd | Real estate | 2021 |
| Inicio Tutors Ltd | Education | 2012 |
| Initiator Limited | Financial services | 2004 |
| INK Employee Benefits Limited | Financial services | 2013 |
| INK HR Limited | Professional & scientific | 2009 |
| Innovate Business Consulting Ltd | Professional & scientific | 2023 |
| Innovative Systems Partnership Limited | Real estate | 2003 |
| Inovex Software Limited | Manufacturing | 2015 |
| Inspimove Limited | Real estate | 2022 |
| Inspirit Performance Limited | Education | 2007 |
| Instructus | Education | 2009 |
| Insync Developments Ltd | Construction | 2021 |
| Integrated Automotive Ltd | Wholesale & retail | 2022 |
| Integrity Quality Solutions Ltd | Professional & scientific | 2025 |
| Interhome (Properties) Limited | Construction | 1973 |
| Intermediary Mortgage Lenders Association | Other services | 1988 |
| International Professional Audio Technologies Limited | Administrative & support | 2008 |
| Interstream Limited | Health & social care | 2018 |
| Intervac Ltd | Manufacturing | 2007 |
| Investment Yield Limited | Real estate | 2001 |
| Invigorated Ltd | Hospitality | 2023 |
| Ipecc Limited | Professional & scientific | 2007 |
| Ipost Manage Limited | Manufacturing | 2024 |
| Ireland and Company Limited | Professional & scientific | 2014 |
| Ireton Web Limited | Other services | 2013 |
| Irle Consultancy Ltd | Administrative & support | 1988 |
| Irle Developments Ltd | Information & communication | 1990 |
| Irle Holdings Ltd | Wholesale & retail | 1999 |
| Iron Tiger Development Limited | Professional & scientific | 2020 |
| Iron Tiger Limited | Wholesale & retail | 2017 |
| Iron Tiger Services Limited | Wholesale & retail | 2020 |
| Isabella Lettings Ltd | Real estate | 2025 |
| Isis Forestry Limited | Agriculture & fishing | 2010 |
| Iskah Consulting Limited | Information & communication | 2024 |
| ITP Events Limited | Arts & recreation | 2013 |
| IVY Law Limited | Professional & scientific | 2014 |
| IVY Timber Structures Ltd | Construction | 2013 |
| Iwan Ltd | Hospitality | 2023 |
| J & GC PM Services Ltd | Professional & scientific | 2020 |
| J & J Avedisian Limited | Hospitality | 2017 |
| J & J Roofs Limited | Manufacturing | 2002 |
| J & S White Farms Limited | Information & communication | 2002 |
| J Burrows Carpentry Ltd | Construction | 2023 |
| J Culleton Solutions Limited | Wholesale & retail | 2007 |
| J D Excavations Limited | Construction | 1999 |
| J G Locksmiths Limited | Administrative & support | 2010 |
| J LEE Telecoms Ltd | Construction | 2019 |
| J M S Property Services Limited | Real estate | 2015 |
| J P Engineering Services Ltd | Professional & scientific | 2025 |
| J R Centrepieces Limited | Manufacturing | 2015 |
| J R Percival Holdings Ltd | Agriculture & fishing | 2019 |
| J S Szafranski Limited | Health & social care | 2012 |
| J Scott&Son Roofing&Building Ltd | Construction | 2024 |
| J Stamp & Sons Limited | Other services | 2013 |
| J V Plumbing & Heating Limited | Construction | 2013 |
| J&De Limited | Wholesale & retail | 2017 |
| J&S Baggott Ltd | Construction | 2017 |
| J.A Horton Homes Ltd | Real estate | 2023 |
| J.C Decorations Ltd | Administrative & support | 2017 |
| J.L.W.B Investments Ltd | Professional & scientific | 2021 |
| J.R. Percival Limited | Agriculture & fishing | 1972 |