| Highgate Private Ltd | Professional & scientific | 2018 |
| Highways (UK) Limited | Construction | 2011 |
| Hilarioliz K Limited | Health & social care | 2014 |
| HIP HOP Museum LLP | | 2020 |
| Hitea WGC Ltd | Hospitality | 2023 |
| Hive Industries Limited | Manufacturing | 1996 |
| HKZ Productions Ltd | Information & communication | 2008 |
| HL Electrical Ltd | Construction | 2018 |
| HM Portfolio Ltd | Real estate | 2022 |
| HNL International (UK) Limited | Professional & scientific | 2007 |
| Hodge (Lighting) Limited | Wholesale & retail | 1964 |
| Holdings Limited | Professional & scientific | 1993 |
| Holiday Planners Ltd | Administrative & support | 2010 |
| Holly Corner Kindergarten Limited | Education | 1998 |
| Hollybush Clinic WGC Ltd | Health & social care | 2015 |
| Holman Property (Holding) Limited | Financial services | 2019 |
| Home and Business Charging Ltd | Wholesale & retail | 2018 |
| Home Extension Team (ST Albans) Ltd | Professional & scientific | 2021 |
| Home Sellers Packs Ltd | Administrative & support | 2004 |
| Homecare 360 Ltd | Health & social care | 2021 |
| Homecare Living Ltd | Health & social care | 2013 |
| Hongyunge Limited | Hospitality | 2024 |
| Hopping Duck Limited | Arts & recreation | 2021 |
| Hostech Limited | Information & communication | 2023 |
| Hot Property Team Limited | Real estate | 2024 |
| House of Mezze Ltd | Hospitality | 2024 |
| Howlands Estate Management Company Limited | Households | 2003 |
| HPG Industrial Coatings Pension Trustees Limited | Extraterritorial | 1998 |
| HUC South West Limited | Health & social care | 2004 |
| Hucknall Day Nursery Holdings Limited | Financial services | 2019 |
| Hucknall Day Nursery Limited | Education | 2019 |
| Hunbuild Ltd | Construction | 2008 |
| Hurrah Consultants Ltd | Professional & scientific | 2023 |
| Hurst & Partners LLP | | 2015 |
| Hutch Creative LLP | | 2012 |
| HVN Events Ltd | Hospitality | 2024 |
| HVR Tanner Ltd | Construction | 2023 |
| Hyde Way Cafe Limited | Hospitality | 2025 |
| Hydrocert Limited | Professional & scientific | 2008 |
| Hydrocert Property Ltd | Real estate | 2022 |
| Hypr Group Ltd | Information & communication | 2024 |
| HZ Enterprises & Solutions Limited | Wholesale & retail | 2026 |
| I Care 1826 Limited | Extraterritorial | 2013 |
| I Picture This C.I.C. | Education | 2019 |
| I-Movo Holdings Limited | Financial services | 2003 |
| I-Movo Limited | Information & communication | 2009 |
| IAM Drive & Survive Limited | Education | 1986 |
| IAM Driver Retraining Academy Limited | Professional & scientific | 2012 |
| IAM Group Services Ltd. | Wholesale & retail | 1960 |
| IAM Motoring Trust Trading Limited | Extraterritorial | 2002 |
| IAM Roadsmart Limited | Extraterritorial | 2002 |
| Iapg Ltd | Real estate | 2020 |
| Ibrowsnlash Limited | Other services | 2020 |
| Icarus Incorporated Ltd | Information & communication | 2014 |
| Icedelights Ltd | Hospitality | 2018 |
| Iclarify Ltd | Professional & scientific | 2009 |
| ICS Globe Europe Ltd | Wholesale & retail | 2016 |
| Ideal BIM Ltd | Administrative & support | 2019 |
| Iderm Limited | Other services | 2012 |
| Idolo LLP | | 2024 |
| IFJ Events Ltd | Wholesale & retail | 2026 |
| Igad Ltd | Information & communication | 2026 |
| IGL Films Ltd | Information & communication | 2019 |
| IHL Services Limited | Administrative & support | 2024 |
| IKB Networks Ltd | Information & communication | 2018 |
| Imagination Atlas Ltd | Administrative & support | 2017 |
| Imagine IF Films Ltd | Information & communication | 2014 |
| Imagine Pharmacovigilance Ltd | Professional & scientific | 2021 |
| Immobilier Anglais Limited | Real estate | 2019 |
| Impact Design and Media Limited | Other services | 2011 |
| Imperial Care 24/7 Limited | Health & social care | 2012 |
| Imperium Payroll Services Ltd | Professional & scientific | 2018 |
| Impex Freight Limited | Transport & logistics | 2026 |
| IN Esse Ltd | Construction | 2014 |
| IN the Mind Ltd | Professional & scientific | 2024 |
| In-Habit Enterprises Limited | Professional & scientific | 2013 |
| IN2ON Limited | Professional & scientific | 2007 |
| Incorporate Secretariat Limited | Professional & scientific | 2001 |
| Incult Projects Ltd | Arts & recreation | 2023 |
| Independent Living Supplies Limited | Information & communication | 2009 |
| Individu Consulting Ltd | Information & communication | 2025 |
| Infinity Group UK Holdings Limited | Financial services | 2022 |
| Infinity Plant Ltd | Construction | 2020 |
| Infotox Limited | Professional & scientific | 2013 |
| Inhana Education Ltd | Education | 2024 |
| Inhouse Property Group Limited | Construction | 2026 |
| Inkcow Ltd | Information & communication | 2026 |
| Innit Limited | Information & communication | 2018 |
| Innovate Scaffolding Ltd | Construction | 2017 |
| Innovative Investments International Ltd | Real estate | 2019 |
| Innsway Developments Limited | Real estate | 2016 |
| Inspace Mechanical & Electrical Limited | Construction | 2010 |
| Inspired Integrated Systems Ltd | Administrative & support | 2015 |
| Institute of Advanced Motorists Limited(The) | Education | 1956 |
| Insurance Collections Bureau Ltd | Administrative & support | 2005 |
| Integra Physiotherapy & Performance Ltd | Other services | 2023 |
| Intelligent Design Hub Limited | Wholesale & retail | 2026 |
| Intelligent Storage WGC Ltd | Transport & logistics | 2011 |
| Intenda UK Ltd | Information & communication | 2005 |
| Intermune Holdings Limited | Professional & scientific | 2012 |