| Hunter Construction 88 Ltd | Construction | 2025 |
| Hussey Quality Butchers Ltd | Wholesale & retail | 2023 |
| Hutchison I.T. Solutions Limited | Information & communication | 2018 |
| Hvac Cooling and Heating Services Ltd | Construction | 2018 |
| Hwnh (Holdings) Ltd | Professional & scientific | 2021 |
| HWO Consulting Ltd | Real estate | 2023 |
| Hybrid Network Family (UK) Limited | Information & communication | 2012 |
| Hydrogen Power & Energy Ltd | Professional & scientific | 2022 |
| Hype Van Ltd | Information & communication | 2021 |
| Hyssop Health Ltd | Health & social care | 2023 |
| I.P.S Electrical Installations Ltd | Construction | 2018 |
| I25FOUR Limited | Real estate | 2024 |
| IAH Property Management Ltd | Real estate | 2023 |
| Iame Projects Limited | Construction | 2024 |
| Ibex Consultants Ltd. | Professional & scientific | 1987 |
| Ibhar Ltd | Wholesale & retail | 2014 |
| Ica:Uk | Education | 2000 |
| Icey Cosmetics Ltd | Other services | 2025 |
| Ickenham Carwash Ltd | Other services | 2019 |
| Iclean Valeting Limited | Administrative & support | 2024 |
| ICN Enterprises Ltd | Hospitality | 2012 |
| Icon.Boxing Ltd | Manufacturing | 2022 |
| Idea Warehouse Ltd | Professional & scientific | 2023 |
| Ideal Food Ingredients Limited | Manufacturing | 2003 |
| Ideal UK Properties Ltd | Real estate | 2024 |
| Idimak Limited | Wholesale & retail | 2020 |
| IEA Realty Ltd | Real estate | 2018 |
| Ierp Ltd | Information & communication | 2012 |
| IFA Creations Ltd | Construction | 2017 |
| Igniteco Group Ltd | Construction | 2024 |
| Igsd Creative Services Limited | Manufacturing | 2023 |
| IHU Catering Ltd | Hospitality | 2023 |
| IIC Digital Ltd | Professional & scientific | 2023 |
| Ikonic Building Design Ltd | Professional & scientific | 2009 |
| Ikonic Consultants Ltd | Construction | 2016 |
| ILI Consulting Ltd | Professional & scientific | 2024 |
| Illusions Online UK Limited | Administrative & support | 2015 |
| Illy Maintenance Ltd | Construction | 2025 |
| Ilondon Travels Ltd | Transport & logistics | 2018 |
| Image Editing Place Ltd | Information & communication | 2023 |
| Imap Limited | Real estate | 1959 |
| Imho Technologies Limited | Information & communication | 2017 |
| Impart ID Limited | Other services | 2023 |
| Impartial Consultant Ltd | Professional & scientific | 2023 |
| Imperial Auto Trade Ltd | Wholesale & retail | 2020 |
| Imperial Fiber Tech UK Ltd | Professional & scientific | 2020 |
| Imperial International Holdings Group Ltd | Other services | 2024 |
| Imperial International Holdings Ltd | Other services | 2024 |
| Imperial Meat Supply Ltd | Wholesale & retail | 2026 |
| Imperial Prime Ltd | Professional & scientific | 2023 |
| Imperial Real Estates Limited | Wholesale & retail | 2020 |
| Imperial Roofers Limited | Construction | 2025 |
| Imperial Supplies Ltd | Wholesale & retail | 2016 |
| Imperial Travel UK Ltd | Wholesale & retail | 2001 |
| Impervious Roofing & Building Ltd | Construction | 2017 |
| Impex UK Limited | Wholesale & retail | 2002 |
| Impulse Clicks Limited | Administrative & support | 2022 |
| In-Service Hospitality Ltd | Professional & scientific | 2026 |
| Incohare Ventures Ltd | Information & communication | 2015 |
| Incrementum Surgical Ltd | Manufacturing | 2026 |
| Incus Solutions Ltd | Professional & scientific | 2024 |
| Independent Investments Limited | Construction | 2003 |
| Independent Safety Design Limited | Administrative & support | 2019 |
| Independent Solution Design Ltd | Administrative & support | 2025 |
| India Middle East Agri Alliance Limited | Wholesale & retail | 2023 |
| Indira Consulting Limited | Professional & scientific | 2014 |
| Indon Foods Limited | Hospitality | 2024 |
| Indorider Ltd | Manufacturing | 2025 |
| Inevitable Energy Limited | Energy | 2025 |
| Infiiniite UK Limited | Real estate | 2025 |
| Infinity ARC Limited | Wholesale & retail | 2025 |
| Infinity Furnishing Ltd | Wholesale & retail | 2021 |
| Infinity Mortgage Solutions Limited | Financial services | 2016 |
| Infinity Tiles and Bathrooms Limited | Construction | 2017 |
| Influencebazar Media Ltd | Professional & scientific | 2023 |
| Infobit Inc Ltd | Information & communication | 2023 |
| Infold Limited | Information & communication | 1992 |
| Infotech Data Services Limited | Information & communication | 2023 |
| Ingenium Recruitment Ltd | Administrative & support | 2021 |
| INGLES2DAY Ltd | Education | 2025 |
| INK & Echo Limited | Information & communication | 2026 |
| INK187UK Ltd | Other services | 2015 |
| Inked Limited | Wholesale & retail | 2019 |
| Inlighten Life Limited | Other services | 2020 |
| Inn PUB Group 2 Limited | Hospitality | 2020 |
| Inn PUB Group Ltd | Hospitality | 2020 |
| Innersight Consulting Ltd | Professional & scientific | 2013 |
| Innertise Ltd | Professional & scientific | 2020 |
| Inno Finance Ltd | Extraterritorial | 2016 |
| Innovate Real Estates Ltd | Real estate | 2024 |
| Innovatious Limited | Information & communication | 2015 |
| Innovative Mortgage & Protection Ltd | Education | 2024 |
| Innovative Source Co., Limited | Extraterritorial | 2021 |
| Insa Innovations Limited | Information & communication | 2019 |
| Insha Bhat Ltd | Health & social care | 2023 |
| Insideout London Ltd | Construction | 2007 |
| Insight Editing London Ltd. | Professional & scientific | 2020 |
| Insight Mortgage Business Limited | Financial services | 2017 |
| Insight Through Science Ltd | Information & communication | 2013 |
| Insightfull Publishing Limited | Information & communication | 2018 |