| Howe's Clearance Limited | Water & waste | 2016 |
| Howe's Plumbing & Heating Limited | Construction | 2024 |
| HPC Talent Group Limited | Administrative & support | 2025 |
| HR Auto Expo Ltd | Wholesale & retail | 2025 |
| HR Motoring Ltd | Wholesale & retail | 2021 |
| HR Project Solutions Ltd | Other services | 2017 |
| HRH Food & Services Ltd | Hospitality | 2020 |
| Hrlife Ltd | Administrative & support | 2017 |
| HSD Vehicle Diagnostics Ltd | Administrative & support | 2010 |
| HSG Technologies Ltd | Information & communication | 2024 |
| HST Digital Services Ltd | Professional & scientific | 2016 |
| Huddle Sports Events Limited | Arts & recreation | 2025 |
| Humiseal Europe Limited | Manufacturing | 1980 |
| Humphris Hall Ltd | Financial services | 2010 |
| Humphris Hall Technology Services Limited | Information & communication | 2011 |
| Hundredchefs Ltd | Hospitality | 2025 |
| Hungry Film Limited | Information & communication | 2024 |
| Hunters Chase (Chesham) Management Company Limited | Households | 2004 |
| Huntsman's Meadow/Woodcote Place Management Limited | Real estate | 1995 |
| Hurst Park Management Company Limited | Households | 1992 |
| Hurst Park NO. 2 Management Company Limited | Households | 1993 |
| Hurst Studios Photography Limited | Professional & scientific | 2023 |
| Hussey Automotive Ltd | Wholesale & retail | 2022 |
| HVR Clinical Psychology Ltd | Health & social care | 2022 |
| Hvra Limited | Other services | 2020 |
| Hwpsb Limited | Financial services | 2025 |
| HX Studio Ltd | Information & communication | 2025 |
| Hydrogen Networks Limited | Energy | 2020 |
| Hylo Athletics Limited | Manufacturing | 2019 |
| I AM S3 Limited | Information & communication | 2025 |
| I C Investment Property Ltd | Real estate | 2025 |
| I Love Windsor C.I.C. | Information & communication | 2010 |
| I Married a Cultist Holdco Limited | Information & communication | 2024 |
| I Married a Cultist Limited | Information & communication | 2024 |
| I-Arivan Consulting Limited | Information & communication | 2015 |
| I-Mob Ltd | Wholesale & retail | 2013 |
| IAC Consulting Ltd | Professional & scientific | 2018 |
| Iain C White Business Consultant Limited | Professional & scientific | 2014 |
| IAN LEE Builder Limited | Construction | 2005 |
| IB Transport Limited | Transport & logistics | 2023 |
| Icashcars Ltd | Wholesale & retail | 2017 |
| Icesupp Ltd | Manufacturing | 2021 |
| ICG Collective Ltd | Administrative & support | 2025 |
| Ichor Ltd | Information & communication | 2016 |
| Iconic Build Life Ltd | Real estate | 2024 |
| Iconic Project Management Ltd | Professional & scientific | 2018 |
| Iconic Vitam Ltd | Financial services | 2024 |
| ICS Diagnostic Solutions Limited | Professional & scientific | 2025 |
| ICU2 Cctv Ltd | Administrative & support | 2022 |
| ICW Holdings Limited | Financial services | 2026 |
| ID Coaching Ltd | Arts & recreation | 2020 |
| Idajack Ltd | Health & social care | 2017 |
| Ideal Double Glazing Limited | Construction | 2019 |
| Idemia Identity & Security UK Limited | Information & communication | 2007 |
| Identity Digital Studio Limited | Information & communication | 2019 |
| Idiosynergy Consultancy Ltd | Professional & scientific | 2017 |
| Idle Coffee Ltd | Hospitality | 2026 |
| Idowaz Technologies & Media Group Limited | Information & communication | 2017 |
| IDP Automation Ltd | Wholesale & retail | 2015 |
| IEP Infrastructure Holdco Limited | Financial services | 2017 |
| IEP Infrastructure Topco Limited | Financial services | 2017 |
| Ifill Holdings Ltd | Real estate | 2024 |
| Ifox One LLP | | 2026 |
| Ign!Te Creative Studio Ltd | Professional & scientific | 2025 |
| Ignition IQ Ltd | Information & communication | 2026 |
| Ignition Spark Ltd | Wholesale & retail | 2020 |
| IGT Electrical Ltd | Construction | 2023 |
| IJ Magilton Limited | Professional & scientific | 2019 |
| Ijak Residential Limited | Real estate | 2020 |
| Illuminaction Ltd | Information & communication | 2006 |
| Illyrian Group Ltd | Real estate | 2024 |
| Image-Corporate Limited | Professional & scientific | 1999 |
| Imagebase Technology Limited | Information & communication | 1988 |
| Imagination Children's Role Play Limited | Arts & recreation | 2016 |
| Imaginative Cuisine Limited | Wholesale & retail | 2003 |
| Immersed Live Ltd | Information & communication | 2023 |
| Immovable Midco Ltd | Administrative & support | 2023 |
| Immovable Studios Limited | Information & communication | 2022 |
| Imms Natives SPV Limited | Information & communication | 2024 |
| Imperial Court ( Wokingham ) Management Company Limited | Households | 2007 |
| Imperial Court (Wokingham) Freehold Limited | Households | 2010 |
| Imperium Connect Ltd | Administrative & support | 2026 |
| Imperium TNT Ltd | Hospitality | 2025 |
| IN4TYRES Limited | Water & waste | 2026 |
| Incar-Science Ltd | Administrative & support | 2007 |
| Independent Professional Services Limited | Information & communication | 1980 |
| Indexon Training Ltd | Information & communication | 2009 |
| Indigo Access Ltd | Health & social care | 2012 |
| Indio Lakes Limited | Hospitality | 2023 |
| Infinidev Limited | Information & communication | 2012 |
| Infinitus Developments Limited | Real estate | 2021 |
| Inflatable Kingdom Ltd | Administrative & support | 2026 |
| INFO4 Limited | Financial services | 2000 |
| Infomedia Publishing Limited | Information & communication | 2009 |
| Infotech Air-Conditioning Ltd | Construction | 2013 |
| Ingenerco Limited | Information & communication | 2006 |
| Ingenious Renewable Energy Lending Services Limited | Administrative & support | 2015 |
| Ingenious Software Solutions Ltd | Information & communication | 2020 |
| Inkfusion Ltd | Other services | 2025 |
| Inkspiring Ltd | Manufacturing | 2024 |