| Hxband Limited | Manufacturing | 2023 |
| Hybrid Networks Telecom Solutions Ltd | Construction | 2022 |
| Hyde Park Finance Ltd | Financial services | 2015 |
| Hygihub Ltd | Manufacturing | 2025 |
| Hymer (UK) Limited | Wholesale & retail | 2012 |
| Hymer Limited | Wholesale & retail | 2012 |
| Hyperion Site Services Ltd | Construction | 2019 |
| Hyperlaw Limited | Information & communication | 2015 |
| Hyperscale Networks Ltd | Information & communication | 2025 |
| I & L Emmerson Holdings Limited | Financial services | 2020 |
| I a News Ltd | Wholesale & retail | 2017 |
| I Fitness and Health Limited | Arts & recreation | 2016 |
| I H Freelance Services Limited | Manufacturing | 2003 |
| I S E Estates Limited | Real estate | 2003 |
| I-V-K Image Co Limited | Extraterritorial | 2013 |
| I.C.Limited | Manufacturing | 1987 |
| IAN Bailey Electrical Limited | Construction | 2015 |
| IAN Dowson (Blinds) Limited | Wholesale & retail | 2003 |
| IAN Hough & Associates (UK) Limited | Professional & scientific | 2024 |
| IAN Williams Partnership EPC Limited | Professional & scientific | 2012 |
| IAN Williams Partnership Limited | Professional & scientific | 2010 |
| Ians Fishing Tackle Ltd | Wholesale & retail | 2025 |
| Iasio Consultancy Ltd | Professional & scientific | 2025 |
| Iasio Holdings Ltd | Financial services | 2025 |
| Iasio Property Management Limited | Extraterritorial | 2022 |
| IB22 Engineering Solutions Limited | Professional & scientific | 2017 |
| IBS Dalian Co., Ltd | Extraterritorial | 2016 |
| Ice Tiger Solutions Ltd | Administrative & support | 2024 |
| Icell (HK) Int'L Co., Limited | Manufacturing | 2023 |
| ICS Dataware Ltd | Information & communication | 2013 |
| Icszso Ventures Ltd | Real estate | 2025 |
| IDC Facilities Limited | Administrative & support | 2015 |
| IEC Contracting Limited | Administrative & support | 2017 |
| IER Holding Ltd | Financial services | 2026 |
| IFO Limited | Extraterritorial | 2019 |
| Ifrc Ltd | Professional & scientific | 2015 |
| Ignis-Uk Ltd | Construction | 2023 |
| Iheating Ltd | Construction | 2017 |
| Ikon Bodyz & Mekaniks Ltd | Wholesale & retail | 2016 |
| Ileri Healthcare Ltd | Health & social care | 2025 |
| Imagine Life Medical Ltd | Manufacturing | 2024 |
| Imbue Marketing Ltd | Administrative & support | 2018 |
| Immersive LBE Ltd | Professional & scientific | 2020 |
| Impact Social Work Consultancy Limited | Professional & scientific | 2024 |
| Impact Wealth Management Limited | Financial services | 2012 |
| Impactful Limited | Education | 2015 |
| Impala Adventures Limited | Administrative & support | 2019 |
| Impressions Painting & Decorating Limited | Construction | 2012 |
| Impromptu Limited | Education | 1998 |
| In-Syscon Limited | Information & communication | 2019 |
| Incendium Fire Protection Consultants Limited | Professional & scientific | 2024 |
| Incept Limited | Financial services | 2023 |
| Incube Limited | Manufacturing | 2007 |
| Independent Hospitality Association Ltd | Hospitality | 2024 |
| Independent Hseq Advisory Services Ltd | Professional & scientific | 2022 |
| Industrial Door Contracts Limited | Construction | 2010 |
| Industrial Electric Elements Limited | Manufacturing | 2003 |
| Inext Home Renovations Ltd | Other services | 2014 |
| Infinite EA LUX Gold Ltd | Wholesale & retail | 2023 |
| Infinity Film & TV Productions Ltd | Information & communication | 2017 |
| Infinity MEP Limited | Professional & scientific | 2019 |
| Infinity Sourcing Co., Ltd. | Wholesale & retail | 2024 |
| Infinity Surgery Limited | Health & social care | 2020 |
| Inflata Playsports Limited | Arts & recreation | 2018 |
| Inflatanation (Newcastle Upon Tyne) Limited | Administrative & support | 2018 |
| Inflatanation (Newcastle) Trading Ltd | Arts & recreation | 2019 |
| Inflow (UK) Limited | Manufacturing | 1992 |
| Infoplanet International Data Center Limited | Manufacturing | 2025 |
| Ingb Solutions Limited | Wholesale & retail | 2017 |
| Ingestre Golf Club Limited | Arts & recreation | 1972 |
| Ingestre Park Golf Club Limited | Arts & recreation | 2012 |
| Ingestre Properties Limited | Administrative & support | 2002 |
| Inglewood Investment Company Limited(The) | Real estate | 1951 |
| Ingrid's Hair&Beauty Salon Ltd | Other services | 2022 |
| Inhi International Ltd | Wholesale & retail | 2025 |
| Inical Ltd | Professional & scientific | 1981 |
| Inis Cara Developments Limited | Construction | 2003 |
| INITI8CHANGE Ltd | Professional & scientific | 2023 |
| Inkwell Video Ltd | Information & communication | 2022 |
| Inky Needles Ltd | Other services | 2015 |
| INL Associates Ltd | Professional & scientific | 2011 |
| INL Consultancy Ltd | Professional & scientific | 2005 |
| Inland and Coastal Ltd | Information & communication | 2021 |
| Inlane UK Limited | Professional & scientific | 2003 |
| Innovation Home Improvements Ltd | Construction | 2026 |
| Innovation Inspired Limited | Manufacturing | 2020 |
| Innovative Business Change Solutions Ltd | Information & communication | 2015 |
| Inscope Property Consultants Ltd | Professional & scientific | 2017 |
| Insert Copy Ltd | Professional & scientific | 2021 |
| Inside OUT (Stafford) Limited | Wholesale & retail | 2003 |
| Insight Multi Academy Trust | Education | 2016 |
| Inspec Comms Limited | Information & communication | 2021 |
| Inspire Aerial Images Limited | Professional & scientific | 2015 |
| Instant Quizzes Ltd. | Arts & recreation | 2000 |
| Instantiex Limited | Wholesale & retail | 2021 |
| Institute of Explosives Engineers | Information & communication | 2012 |
| Insulation Services (Europe) Limited | Construction | 2018 |
| Inta Eco Limited | Manufacturing | 2007 |
| Intaco Limited | Construction | 1991 |
| Intandem Promotions UK Limited | Wholesale & retail | 2020 |