| House of Visuals Limited | Information & communication | 2025 |
| HOUSE2BUY Limited | Real estate | 2017 |
| HP Prestige Limited | Administrative & support | 2004 |
| HS Prime Properties Ltd | Real estate | 2018 |
| HTJ Properties Ltd | Real estate | 2021 |
| Human Intelligence Technologies Limited | Information & communication | 2026 |
| Humble BEE Mandarin Limited | Hospitality | 2020 |
| Hume Interior Studio Ltd | Professional & scientific | 2020 |
| Hunter Broxburn Limited | Real estate | 2018 |
| Hurst Publications Limited | Information & communication | 2014 |
| Hussaini and Company Limited | Health & social care | 2013 |
| Hydren Group Ltd | Construction | 2025 |
| Hydreo Limited | Wholesale & retail | 2025 |
| Hyntech Limited | Information & communication | 2023 |
| I Love Yo-Chi Ltd | Hospitality | 2025 |
| IA & Sons Ltd | Wholesale & retail | 2026 |
| Iberflavours UK Ltd | Wholesale & retail | 2021 |
| Iberian Shutters Ltd | Construction | 2025 |
| IBM Joinery Ltd | Construction | 2019 |
| IC Accountants Ltd | Professional & scientific | 2020 |
| ICG Trades Limited | Wholesale & retail | 2021 |
| Iconic Interiors London Ltd | Manufacturing | 2023 |
| Ideal Development & Business Solutions Ltd | Information & communication | 2025 |
| Ideal Mortgage Advice Ltd | Financial services | 2019 |
| Ideal Roofing & Building Works Limited | Construction | 2026 |
| Igniteapp Ltd | Information & communication | 2025 |
| Image Projects Surrey Ltd | Construction | 2026 |
| Iman Holdings Ltd | Professional & scientific | 2025 |
| Immensus Limited | Professional & scientific | 2024 |
| Imperial Meat Market Limited | Wholesale & retail | 2026 |
| IMPERIALTR1BE Ltd. | Health & social care | 2024 |
| Imperium Building Systems Limited | Construction | 2014 |
| Impossible Dream LG Ltd | Information & communication | 2021 |
| Inclusive Health Ltd | Health & social care | 2023 |
| Inclusive Rowing Ltd | Education | 2021 |
| Indian Guru Ltd | Hospitality | 2025 |
| Indian Oasis London Ltd | Hospitality | 2023 |
| Inds Consultants Ltd | Professional & scientific | 2024 |
| Infinite Access Ltd | Construction | 2024 |
| Infizon Investment Limited | Real estate | 2024 |
| Inkarter Limited | Information & communication | 2013 |
| Inmotion With Marcella Ltd | Other services | 2025 |
| Innoratech PVT Ltd | Information & communication | 2010 |
| Innotech Education Ltd | Information & communication | 2026 |
| Innovateach Limited | Information & communication | 2021 |
| Innovative Web Services Ltd | Information & communication | 2010 |
| Inotary Limited | Professional & scientific | 2021 |
| Insightful Talent Limited | Administrative & support | 2024 |
| Inspire Kids Foundation | Wholesale & retail | 2010 |
| Institute of Search and Technical Rescue | Other services | 2013 |
| Instr (Consulting) Limited | Professional & scientific | 2023 |
| INT Construction Ltd | Construction | 2017 |
| Integrated Comms Ltd | Professional & scientific | 2023 |
| Intellipro Group UK Limited | Information & communication | 2020 |
| Interior Solution Consultants Limited | Professional & scientific | 2010 |
| International Shuheng Acupuncture Research Association Ltd | Education | 2019 |
| Interskan Limited | Professional & scientific | 2012 |
| ION Fire Stopping Ltd | Construction | 2026 |
| Irdis Ltd | Information & communication | 2008 |
| Isuna ISE Limited | Professional & scientific | 2019 |
| IT Deliverance Limited | Information & communication | 2008 |
| ITD Hosting Ltd | Information & communication | 2011 |
| ITI Drylining Ltd | Construction | 2021 |
| IVM Construction Ltd | Construction | 2013 |
| Izol Limited | Education | 2020 |
| J B Plastering & Building Services Limited | Construction | 2016 |
| J Cullen Building Services Ltd | Construction | 2010 |
| J S Morleys Ltd | Hospitality | 2018 |
| J&K Residential Limited | Real estate | 2024 |
| J.A & A.T Logistics Ltd | Transport & logistics | 2023 |
| J.A.G Property Letting Ltd | Real estate | 2019 |
| Jaan Trading Ltd | Hospitality | 2017 |
| Jacksons Roofing Ltd | Extraterritorial | 2024 |
| Jacksons Scaffolding Access Solutions Ltd | Construction | 2020 |
| Jacksons Scaffolding Services Ltd | Construction | 2019 |
| Jacob's Removals and Storage Ltd | Transport & logistics | 2023 |
| JAI Fintech Ltd | Financial services | 2020 |
| Jaigau Medical Ltd | Health & social care | 2019 |
| JAKAR97 Limited | Hospitality | 2025 |
| Jake Webster Ltd | Health & social care | 2024 |
| James Gardiner Ltd | Arts & recreation | 2025 |
| Jampz Ltd | Construction | 2015 |
| Jansee Holdings Limited | Real estate | 2025 |
| Janus Commercial Contracts Limited | Construction | 2019 |
| Jasvi Ltd | Real estate | 2024 |
| Jauri KJD Ltd | Real estate | 2024 |
| Jawd Ltd | Wholesale & retail | 2022 |
| Jaxan (London) Ltd | Professional & scientific | 2013 |
| Jayheen Limited | Wholesale & retail | 2009 |
| Jayshouse Park Ltd | Health & social care | 2021 |
| Jaytraders Limited | Wholesale & retail | 2026 |
| JB Consulting (MDP) Limited | Professional & scientific | 2011 |
| Jbsb Holdings Limited | Real estate | 2025 |
| JD Property Improvement Ltd | Construction | 2023 |
| Jdancestudios | | 2006 |
| JDG Mechanical Limited | Construction | 2024 |
| Jeni M T Company Ltd | Wholesale & retail | 2021 |
| Jenisi Associates Limited | Administrative & support | 2002 |
| Jetway Travel & Tours Ltd | Administrative & support | 2019 |
| JEY Group Ltd | Real estate | 2024 |