| Huacracocha Ventures Ltd | Manufacturing | 2020 |
| Hub Personnel Ltd | Real estate | 2024 |
| Hughson Brothers Limited | Professional & scientific | 2011 |
| Hugo Brownboy Limited | Real estate | 2008 |
| Human Transformation Works Group Ltd | Professional & scientific | 2026 |
| Humane Pest Control Herts Limited | Other services | 2022 |
| Humble Dani Care Ltd | Administrative & support | 2023 |
| Hunkar CAN Ltd | Hospitality | 2017 |
| Hunkydory Publishing Limited | Information & communication | 2007 |
| Huntercombe Court (Two) Management Company Limited | Households | 2006 |
| Huntpictures Ltd | Professional & scientific | 2017 |
| Hursts Electrical Ltd | Construction | 2012 |
| Husco & Associates Limited | Professional & scientific | 2002 |
| Hutchinson Electrical Factors Ltd | Construction | 2015 |
| HW Aesthetics Ltd | Other services | 2019 |
| Hydro GAS Heating Ltd | Construction | 2026 |
| Hydrocity LLP | | 2014 |
| HYM Finance Ltd | Administrative & support | 2025 |
| Hypro Technologies Limited | Information & communication | 2021 |
| I Pharmacistuk Ltd | Health & social care | 2015 |
| I Q Security and Facility Services Ltd | Administrative & support | 2018 |
| I&E Accountancy Ltd | Professional & scientific | 2025 |
| I-Tech Solutions (SET) Limited | Professional & scientific | 2009 |
| I.E.D Investments Ltd | Real estate | 2016 |
| I.J.Installation&Refurbishment Ltd | Construction | 2019 |
| I.R. Energy Network Ltd | Construction | 2024 |
| IA Consultant Services Ltd | Wholesale & retail | 2018 |
| IAN Estates Ltd | Real estate | 2024 |
| IAN Gibbs Estate Management Limited | Real estate | 2004 |
| Ibiza Beat Limited | Manufacturing | 2021 |
| IBL Catering Limited | Hospitality | 2013 |
| Ice Blue Sky Limited | Information & communication | 2007 |
| Ice Blue Vision Ltd | Professional & scientific | 2021 |
| Ice Cold Van Solutions Ltd | Manufacturing | 2020 |
| Ice Cream Wagon Ltd | Hospitality | 2026 |
| Iceighty Limited | Financial services | 2021 |
| Iconic Windows Limited | Construction | 2013 |
| Iconicfs Ltd | Professional & scientific | 2019 |
| ICY Mango Design Ltd | Information & communication | 2024 |
| Ideal Solutions Utilities Ltd | Construction | 2019 |
| Idfolams Ventures Ltd | Information & communication | 2014 |
| IDL Solutions Limited | Construction | 2020 |
| IJ Investments Limited | Real estate | 2021 |
| Ijokitchen Limited | Hospitality | 2020 |
| Ijopec Publication Limited | Information & communication | 2023 |
| IK First Construction Limited | Construction | 2021 |
| Ilkten Properties Ltd | Real estate | 2026 |
| Iloryon Ltd | Transport & logistics | 2021 |
| Imagine Capital Holding Limited | Financial services | 2021 |
| Imaginereel Productions Ltd | Professional & scientific | 2010 |
| Imend Ltd. | Other services | 2012 |
| Impact Builds UK Limited | Construction | 2020 |
| Impact Education Training (South East) Ltd | Education | 2024 |
| Impact Training & Education Ltd | Education | 2023 |
| Imperialpersiamotors Limited | Wholesale & retail | 2026 |
| IMS of Smithfield Ltd. | Wholesale & retail | 1970 |
| IN the Chair Haircare Ltd | Other services | 2023 |
| In-Fity Limited | Real estate | 2025 |
| Incedal's Hairdressing Services Ltd | Other services | 2019 |
| Independent Children Social Work Services Limited | Health & social care | 2023 |
| Indg Ltd | Wholesale & retail | 2011 |
| India Ella Limited | Administrative & support | 2017 |
| Indigo Cleaners Ltd | Administrative & support | 2025 |
| Ineo Logistic Solutions Ltd | Transport & logistics | 2024 |
| Infarex Limited | Wholesale & retail | 2025 |
| Infinite Branding Limited | Administrative & support | 2021 |
| Infinite Heating Services Ltd | Construction | 2024 |
| Infinity FPC Limited | Wholesale & retail | 2024 |
| Infinity Supply Limited | Wholesale & retail | 2023 |
| Influencerconnect Limited | Professional & scientific | 2023 |
| Infomatical Group Holdings Ltd | Other services | 2022 |
| Infytics Ltd | Information & communication | 2023 |
| Inglefield Estates Ltd | Real estate | 2023 |
| Injeniox Limited | Information & communication | 2023 |
| INK Hell Limited | Other services | 2025 |
| Inkin Factory Ltd | Arts & recreation | 2026 |
| Inkin Hub Limited | Financial services | 2025 |
| Inkin Seminar Ltd | Education | 2024 |
| Inkin Studioz Ltd | Arts & recreation | 2022 |
| Inkl Limited | Information & communication | 2024 |
| Inktool Design Ltd | Information & communication | 2005 |
| Inner Vision Experience Ltd | Professional & scientific | 2024 |
| Innsai Construction Ltd | Construction | 2026 |
| Inside and OUT Beauty Limited | Wholesale & retail | 2026 |
| Insight Angels Limited | Professional & scientific | 2015 |
| Insights Unlocked Limited | Information & communication | 2024 |
| Inspiration Hub Limited | Health & social care | 2024 |
| Inspire Beauty World Ltd | Other services | 2018 |
| Inspire ME Creations Ltd | Professional & scientific | 2014 |
| Insta Micro Limited | Wholesale & retail | 2025 |
| Institute of Travel and Tourism(The) | Other services | 1973 |
| Integri Group Ltd | Construction | 2018 |
| Intellego Nexus Limited | Administrative & support | 2020 |
| Intelligent Groundworks Limited | Construction | 2017 |
| Intelligent Houses Ltd | Construction | 2022 |
| Intergrowth Ltd | Wholesale & retail | 2021 |
| International Golden Visa Consultancy Limited | Administrative & support | 2025 |
| International Waltham Cross Limited | Wholesale & retail | 2024 |
| Invent Cleaning Ltd | Administrative & support | 2025 |
| Inventri Ltd | Administrative & support | 2024 |