| Hxcuk Ltd | Real estate | 2025 |
| Hxcuk SPV1 Ltd | Professional & scientific | 2023 |
| Hxcuk SPV2 Ltd | Real estate | 2023 |
| Hxcuk SPV3 Ltd | Real estate | 2026 |
| Hyalpharm Limited | Extraterritorial | 2015 |
| Hyatt Consulting Limited | Professional & scientific | 2012 |
| Hydra Technical Safety Solutions Limited | Construction | 2025 |
| Hydro Property Developments Limited | Real estate | 2024 |
| Hydro Trading Limited | Wholesale & retail | 2022 |
| Hydrostatic Testing Pipeline Services Ltd | Water & waste | 2016 |
| Hydrotec and Engineering Consultants Limited | Professional & scientific | 2015 |
| Hygge Property Management Limited | Real estate | 2020 |
| Hygge Property Trading Limited | Real estate | 2018 |
| Hyland Rigging Ltd | Construction | 2024 |
| Hyperion Aerospace and Industrial Infrastructure Limited | Professional & scientific | 2018 |
| Hypha Restaurants Limited | Hospitality | 2019 |
| Hypharm Limited | Extraterritorial | 2015 |
| Hyphen Blue Ltd | Professional & scientific | 2018 |
| Hyprsan Limited | Professional & scientific | 2020 |
| Hypsu Ltd | Professional & scientific | 2025 |
| I & C Hendry Limited | Wholesale & retail | 2022 |
| I AM Sailing Limited | Real estate | 2022 |
| I B Project Management Limited | Administrative & support | 2011 |
| I Capital International Limited | Administrative & support | 2020 |
| I D Access Ltd | Professional & scientific | 2024 |
| I Data COM Limited | Information & communication | 2008 |
| I Malek Limited | Health & social care | 2015 |
| I SEE Maths Ltd | Education | 2016 |
| I'M NOT Plastic Ltd | Administrative & support | 2019 |
| I-Convergence Ltd | Professional & scientific | 2015 |
| I-Siam Thai Massage & Spa Ltd | Other services | 2022 |
| I.C.P.M.S. Cones Limited | Manufacturing | 2002 |
| I.D.B. Property Developments Limited | Construction | 2024 |
| I4THRIVE Limited | Financial services | 2018 |
| Iain Paul Mcadam Limited | Extraterritorial | 2024 |
| Iain.Bennett Telecoms Ltd | Information & communication | 2021 |
| IAM Compliant Limited | Professional & scientific | 2012 |
| IAM Trade 365 Limited | Wholesale & retail | 2018 |
| IAN Frost Limited | Professional & scientific | 2025 |
| IAN Jeffcott Associates Limited | Administrative & support | 2007 |
| IAT Property Management Limited | Households | 2022 |
| Icarus Cooling Ltd. | Construction | 2022 |
| Ickle BAO Ltd | Manufacturing | 2021 |
| Icons Foundation | Health & social care | 2013 |
| Icons Media Group Ltd | Extraterritorial | 2019 |
| ID Mcdowell Holdings Limited | Financial services | 2026 |
| Idbid Limited | Wholesale & retail | 2025 |
| Ideal Abode Property Investment Ltd | Real estate | 2024 |
| Idee Fixe | Education | 1996 |
| Idoychev Ltd | Real estate | 2024 |
| Ifemy Beauty Salon Ltd | Administrative & support | 2025 |
| IGM Consultants Limited | Professional & scientific | 2020 |
| Ignis Technologies Limited | Health & social care | 2018 |
| Ignite Sustainable Energy Ltd | Professional & scientific | 2014 |
| Ignition Global Ltd | Administrative & support | 2021 |
| Igr.Properties Ltd | Real estate | 2024 |
| IJ GAS Services Ltd | Construction | 2026 |
| IJF Management Consulting Limited | Professional & scientific | 2024 |
| IJM Consultants Limited | Professional & scientific | 2016 |
| IJM Properties Limited | Real estate | 2016 |
| IK Building & Maintenance Ltd | Construction | 2022 |
| Ikonic Group Ltd | Real estate | 2018 |
| Ikonic Holding Group Ltd | Real estate | 2020 |
| Ikonic Management Services Ltd | Administrative & support | 2021 |
| Ikonic Serviced Accommodation Ltd | Hospitality | 2018 |
| Ikonic Training Academy Ltd | Education | 2020 |
| IL Palagione Limited | Hospitality | 2025 |
| Ilach Limited | Wholesale & retail | 2018 |
| Iles Industries Ltd | Hospitality | 2008 |
| Ilieva Bookkeeping and Payroll Limited | Professional & scientific | 2024 |
| ILL Communication Limited | Professional & scientific | 2017 |
| Illingworth Seddon Financial Limited | Financial services | 2021 |
| Illingworth Seddon Group Ltd | Financial services | 2026 |
| Illumex Limited | Manufacturing | 2016 |
| Illuminate Leadership Coaching and Development Ltd | Professional & scientific | 2022 |
| Imagenpay UK Limited | Professional & scientific | 2017 |
| Imaginators Creative Limited | Education | 2025 |
| Imagine Montessori Childcare Ltd | Health & social care | 2023 |
| Imagohr Ltd | Administrative & support | 2018 |
| Imagopm Limited | Professional & scientific | 2021 |
| IMD Consultancy Services Ltd | Professional & scientific | 2024 |
| Imogen Stokes Tattoo Ltd | Other services | 2023 |
| Imogen’S Imaging Ltd | Public administration | 2022 |
| Impact Homes (NW) | Health & social care | 2018 |
| Impact HQ Limited | Wholesale & retail | 2025 |
| Impactech Solutions Ltd | Information & communication | 2017 |
| Impactel Limited | Professional & scientific | 2018 |
| Impakt Claims Ltd | Professional & scientific | 2019 |
| Imperial AST Ltd | Manufacturing | 2025 |
| Imperial IT Business Solutions Ltd | Information & communication | 2011 |
| Imperial Orchid LLP | | 2016 |
| Imperial Pets Ltd | Wholesale & retail | 2015 |
| Imperial Richester Consult Limited | Professional & scientific | 2014 |
| Imperial Shine Carwash Ltd | Wholesale & retail | 2025 |
| Imprint Engine UK Limited | Administrative & support | 2026 |
| Improve Construction Limited | Construction | 2012 |
| IN and OUT Homes Ltd | Hospitality | 2023 |
| IN Motion Clinics Limited | Health & social care | 2015 |
| IN the Fast Lane Ltd | Professional & scientific | 2021 |
| IN the Know Insights Limited | Professional & scientific | 2007 |