| Hygromatics Ltd | Professional & scientific | 2025 |
| Hymac Limited | Manufacturing | 1946 |
| Hyperion Market Intelligence Services Limited | Professional & scientific | 2019 |
| I & M Upholstery Limited | Manufacturing | 2025 |
| I B Plumbing & Heating Services Ltd | Construction | 2023 |
| I Crave Desserts Ltd | Wholesale & retail | 2024 |
| I Love Meet and Greet Ltd | Other services | 2011 |
| I Love Park and Ride Limited | Transport & logistics | 2012 |
| I Majid Solutions Limited | Information & communication | 2026 |
| I&M Social Housing CIC | Hospitality | 2026 |
| I'M Good Ltd. | Information & communication | 2022 |
| I'M Heating & Plumbing Ltd | Administrative & support | 2014 |
| I.D-Tect Ltd | Manufacturing | 2018 |
| I.W.S. Nominee Company Limited | Professional & scientific | 1963 |
| Iago Solutions Limited | Professional & scientific | 2004 |
| IAN Bone Limited | Professional & scientific | 2025 |
| IAN Spooner Developments Limited | Real estate | 1985 |
| IAN Spooner Limited | Real estate | 1963 |
| Ianpaul Care Ltd | Health & social care | 2022 |
| IB Motorworx Ltd | Wholesale & retail | 2026 |
| IC Electricians Ltd | Construction | 2018 |
| Icanprove.It Limited | Administrative & support | 2014 |
| ICC Crawley Ltd | Other services | 2018 |
| Ice Club Ltd | Extraterritorial | 2020 |
| Iceberg Press Limited | Information & communication | 2014 |
| Icecube Hospitality and Recruitment Ltd | Professional & scientific | 2024 |
| Iceround Limited | Transport & logistics | 1986 |
| Icgastapsss Limited | Other services | 2014 |
| Icon Brows Ltd | Health & social care | 2019 |
| Icon Digital Services Limited | Other services | 2007 |
| ICON2 Trade Limited | Wholesale & retail | 2026 |
| ICR8 Ltd. | Professional & scientific | 2021 |
| ICS (Property Cleaning and Maintenance) Limited | Administrative & support | 2011 |
| ICY G&G Limited | Arts & recreation | 2020 |
| Idacio International Services Ltd | Information & communication | 2022 |
| Idan Services Limited | Administrative & support | 2018 |
| IDD Contracts Limited | Construction | 2009 |
| Idea Novum Ltd | Administrative & support | 2014 |
| Ideal Plumbing & Heating Solutions Ltd | Construction | 2016 |
| Idealee Limited | Professional & scientific | 2016 |
| Ideate Design Ltd | Professional & scientific | 2020 |
| IDL Driving School Ltd | Education | 2026 |
| Idng Construction Ltd | Construction | 2023 |
| IEXA100 Consulting Ltd | Professional & scientific | 2009 |
| Ifield Flats (Mount Farm) Limited | Households | 1964 |
| Ifield Green Express Ltd | Wholesale & retail | 2020 |
| Ifield Lodge Ltd | Real estate | 2021 |
| Ifield Software Limited | Information & communication | 1990 |
| Ifield Trading Limited | Information & communication | 2025 |
| IGB Controls and Energy Services Ltd | Professional & scientific | 2013 |
| Igrill Crawley Ltd | Hospitality | 2025 |
| IHK Enterprise Ltd | Wholesale & retail | 2023 |
| IJ Cleaning Services Limited | Administrative & support | 2023 |
| Ijazadnan Ltd | Wholesale & retail | 2020 |
| IJT Associates Limited | Professional & scientific | 2016 |
| Ikase Ltd | Wholesale & retail | 2026 |
| Ikenaa Ltd | Information & communication | 2017 |
| Ikigai Osteopathy Ltd | Health & social care | 2022 |
| IM Autos Limited | Wholesale & retail | 2016 |
| Imagine Aesthetics Ltd | Other services | 2024 |
| Imagine Corp Limited | Financial services | 2024 |
| Imaging Holdings Company Limited | Financial services | 2018 |
| Imaging Midco Ltd | Financial services | 2025 |
| Imak Ltd | Hospitality | 2026 |
| Imbdc Ltd | Professional & scientific | 2018 |
| IMD Caraman Ltd | Construction | 2022 |
| Imgreen Ltd | Energy | 2025 |
| Immortal Tunes Limited | Information & communication | 2025 |
| Immy Barbers Ltd | Education | 2023 |
| Impact Golf Academy Ltd | Arts & recreation | 2024 |
| Impact Harvest Low-Gi Foods Ltd | Agriculture & fishing | 2026 |
| Impact Link Ltd | Professional & scientific | 2019 |
| Impartex Limited | Wholesale & retail | 1984 |
| Impera Consulting Ltd | Professional & scientific | 2025 |
| Imperlimpus Ltd | Administrative & support | 2019 |
| Imposter Creative Ltd | Professional & scientific | 2025 |
| IMS Contracting Ltd | Construction | 2019 |
| IN and OUT Accounting Limited | Professional & scientific | 2019 |
| IN Safer Hands Limited | Information & communication | 2017 |
| IN Total Control (UK) Limited | Information & communication | 2002 |
| In-Vent Services Limited | Construction | 2026 |
| Inclex NO 3 Limited | Information & communication | 2001 |
| Inclex NO 5 Limited | Extraterritorial | 1997 |
| Inclex NO 6 Limited | Extraterritorial | 2001 |
| Inclex NO 7 Limited | Professional & scientific | 1988 |
| Inco Builders Ltd | Administrative & support | 2019 |
| Independent Airport Parking Association Limited | Other services | 2026 |
| Indicore Tech Ltd | Information & communication | 2024 |
| Indigo Life Sciences Ltd | Administrative & support | 2020 |
| Indigo Pumps Ltd | Manufacturing | 2012 |
| Indigoskills Limited | Other services | 2007 |
| Inductus Limited | Information & communication | 1998 |
| Indulge & Associates Ltd | Other services | 2015 |
| Industrial Asylum Ltd | Extraterritorial | 2012 |
| Industrial Communication Products Limited | Wholesale & retail | 2008 |
| Industrial Roofing Group Limited | Construction | 2025 |
| Industrial Waste Recycling Ltd | Water & waste | 2013 |
| Ineo Digital Ltd | Information & communication | 2019 |
| Inferno Kitchen Limited | Hospitality | 2025 |
| Infinite ATV Parts Limited | Wholesale & retail | 2019 |