| HTC Nominees Limited | Professional & scientific | 1996 |
| HTC Secretarial Services Limited | Professional & scientific | 1996 |
| Huff & Puff Property Ltd | Real estate | 2021 |
| Hugh Harris Limited | Arts & recreation | 1946 |
| Huginn and Co Ltd | Wholesale & retail | 2022 |
| Hullabaloo House Ltd | Real estate | 2022 |
| Humelab Hospitality UK Ltd | Administrative & support | 2019 |
| Humphries Engineering Limited | Manufacturing | 2002 |
| Hunters Chase (Haslemere) Residents Management Company Limited | Households | 2023 |
| Hurry Curry Limited | Hospitality | 2025 |
| Hurtwood Capital Limited | Financial services | 2022 |
| Hutchinson & Co. Trustees (Asia) Limited | Professional & scientific | 2013 |
| Hutchinson Estates Limited | Professional & scientific | 1999 |
| Hutchinson Trustees (Lithuania) Limited | Professional & scientific | 2011 |
| Hutchinson Trustees Limited | Professional & scientific | 1996 |
| HVN Psychology Ltd | Education | 2023 |
| Hyde END Road (Spencers Wood) Management Company Limited | Households | 2017 |
| Hyderabad Spice Street Limited | Wholesale & retail | 2026 |
| Hydra Fintech Limited | Information & communication | 2020 |
| Hyperborea Management Ltd | Real estate | 2017 |
| Hyrebrid Fleet Ltd | Administrative & support | 2026 |
| Hyster-Yale UK Pension Co. Limited | Financial services | 1996 |
| Hyvve Limited | Professional & scientific | 2017 |
| HZA Technologies Limited | Information & communication | 2016 |
| I and O Services Ltd | Administrative & support | 2020 |
| I C Property Group Ltd | Real estate | 2021 |
| I T C (Travel) Limited | Administrative & support | 1985 |
| I-Web Solutions Ltd. | Information & communication | 2012 |
| I.D.D.C. Limited | Wholesale & retail | 1989 |
| Ibilots Ventures Limited | Professional & scientific | 2014 |
| Ibos Barber Limited | Other services | 2013 |
| Ibundle Ltd | Professional & scientific | 2008 |
| Ice-Tech Limited | Information & communication | 2017 |
| ICM Logistics Ltd | Transport & logistics | 2025 |
| Iconic Flooring Limited | Construction | 2018 |
| ID MKT Ltd | Professional & scientific | 2019 |
| IDC Europe Ltd | Professional & scientific | 2023 |
| Ideal Health Consultants Limited | Professional & scientific | 2003 |
| Ideal Health Middle East Limited | Professional & scientific | 2018 |
| Ideal Scaffolding (Southern) Ltd | Construction | 2005 |
| Ideal Scaffolding Group Ltd | Real estate | 2016 |
| IE Contractors Limited | Professional & scientific | 1907 |
| Iena Ltd | Wholesale & retail | 2024 |
| Iequinox Ltd | Transport & logistics | 2020 |
| IG Collection Ltd | Wholesale & retail | 2026 |
| Ignatov Delivery Ltd | Transport & logistics | 2018 |
| Ijgfiresafety Limited | Professional & scientific | 2018 |
| IK Facades Ltd | Construction | 2023 |
| IK Store Limited | Wholesale & retail | 2024 |
| Ikigai Streamline Limited | Administrative & support | 2023 |
| Illuminations of Camberley Limited | Wholesale & retail | 2004 |
| Ilyon Consulting Limited | Information & communication | 2005 |
| Ilyonred Ltd | Households | 2015 |
| Image Design Custom Ltd | Professional & scientific | 2007 |
| Image Farnham Ltd | Other services | 2019 |
| Immediate Health Placements Ltd | Administrative & support | 2025 |
| Immediate Leaders Limited | Professional & scientific | 2019 |
| Immediate Transportation Company Limited | Transport & logistics | 1914 |
| Immortal Designs Ltd | Wholesale & retail | 2026 |
| Immuno Leaf Ltd | Wholesale & retail | 2019 |
| Impact Clean Ltd | Administrative & support | 2019 |
| Impact Dynamics Limited | Information & communication | 2002 |
| Impact Evolve Ltd | Professional & scientific | 2022 |
| Impact Regulatory Services Limited | Professional & scientific | 2007 |
| Impact Sales Consulting Limited | Administrative & support | 2022 |
| Imperial Zone System Ltd | Construction | 2026 |
| Imperium R.S Ltd | Professional & scientific | 2009 |
| Impletek Limited | Construction | 2008 |
| Improving Connections Ltd | Professional & scientific | 2023 |
| Improving Experiences Ltd | Professional & scientific | 2026 |
| IMS Lettings Limited | Extraterritorial | 2002 |
| IN Focus IT (UK) Limited | Information & communication | 2005 |
| IN House Agency Leaders Club Ltd | Administrative & support | 2022 |
| IN Touch Communications Thamesway Ltd | Information & communication | 2003 |
| IN360 Ltd | Information & communication | 2020 |
| INA 69 Ltd | Construction | 2020 |
| Inca IT Ltd | Information & communication | 2010 |
| Independent Football Club Consulting Ltd | Professional & scientific | 2022 |
| Indie Ridge Digital Ltd | Information & communication | 2022 |
| Indie Ridge Limited | Professional & scientific | 2016 |
| Indigo Agencies Limited | Hospitality | 2019 |
| Indigo I.T. Ltd | Information & communication | 2002 |
| Indigo Wellbeing Ltd | Professional & scientific | 2015 |
| Indo Pacific Ltd | Real estate | 2025 |
| Industrial Turnkey Solutions Ltd | Information & communication | 2013 |
| Inedyt Vision Limited | Hospitality | 2026 |
| Ines Corporation Ltd | Transport & logistics | 2016 |
| Inex Property Solutions Ltd | Extraterritorial | 2021 |
| Infant Sleep Support With Ellen Ltd | Other services | 2025 |
| Infinity FUN Ltd | Arts & recreation | 2023 |
| Infobiz Solutions Ltd | Information & communication | 2022 |
| Infoprivacy Consultancy Ltd | Information & communication | 2024 |
| Infosit Ltd | Information & communication | 2018 |
| Infosoft Consulting Ltd | Information & communication | 2009 |
| Infotech International Holding Ltd | Real estate | 2026 |
| Infotech International Ltd | Hospitality | 2022 |
| ING Services ( London ) Ltd | Construction | 2017 |
| Inglenook Restoration Ltd | Construction | 2011 |
| Ingram & Co (Southern) Limited | Construction | 2006 |
| INK POT Productions Ltd | Information & communication | 2011 |