| Hughes Housing Investments Limited | Real estate | 2021 |
| Huntsmoor Residents' Association Limited | Other services | 1972 |
| Huxley Capital Partners Ltd | Financial services | 2025 |
| Hybone Ltd | Construction | 2025 |
| Hydra GTA Services Limited | Administrative & support | 2012 |
| Hydrogen Technology Solutions Ltd | Professional & scientific | 2023 |
| Hydrox Ltd | Wholesale & retail | 2020 |
| Hylandsbuild Limited | Administrative & support | 2016 |
| I Love Lucy TV Limited | Professional & scientific | 2010 |
| I-Improve Properties Ltd | Real estate | 2015 |
| Ibtv Ltd | Information & communication | 2024 |
| Icelab 1 Ltd | Health & social care | 2020 |
| Icon Holdings Limited | Wholesale & retail | 2026 |
| Iedp Ideas for Leaders Ltd | Information & communication | 2011 |
| Ikks UK Limited | Professional & scientific | 2006 |
| IL Villino Limited | Real estate | 2023 |
| Immortalit.Ai Limited | Information & communication | 2023 |
| Impactful Holdings Limited | Professional & scientific | 2024 |
| Imperial Wharf (Block C) Limited | Extraterritorial | 2000 |
| Imperial Wharf (Block J) Ltd | Extraterritorial | 2000 |
| Imperial Wharf (Riverside Tower) Residential Limited | Extraterritorial | 2000 |
| Indatel Limited | Information & communication | 1976 |
| Indesign Engineering Ltd | Professional & scientific | 2021 |
| India Oaks Limited | Administrative & support | 2017 |
| Indigo Eight PR Limited | Professional & scientific | 2015 |
| Indigoeight Communications LLP | | 2015 |
| Influentially Limited | Professional & scientific | 2018 |
| Inform Athletes Ltd | Arts & recreation | 2018 |
| Ingvar Angus Associates Ltd. | Professional & scientific | 2014 |
| Inhaus Interiors Limited | Manufacturing | 2019 |
| Innvia Tech LAB Limited | Information & communication | 2025 |
| Inscap Limited | Professional & scientific | 2021 |
| Insight Design Concepts Limited | Professional & scientific | 1998 |
| Insight OUT Research Ltd | Professional & scientific | 2015 |
| Integrated Neurotherapy Association Limited | Information & communication | 2017 |
| Intergration Ltd | Construction | 2025 |
| Interiors by Aida Limited | Professional & scientific | 2009 |
| International Models Ltd | Administrative & support | 2002 |
| International Premier Sports Management Limited | Professional & scientific | 2026 |
| Isandc Services Limited | Administrative & support | 2015 |
| ISG Live Limited | Arts & recreation | 2007 |
| J Campbell Consultancy Limited | Professional & scientific | 2026 |
| J J Planners Ltd | Professional & scientific | 2008 |
| J K Care Limited | Education | 2006 |
| J Ward & Co Ltd | Real estate | 2018 |
| J&T Design and Build Limited | Construction | 2020 |
| J&T Renovations Ltd | Construction | 2023 |
| JAC Management Ltd | Wholesale & retail | 2025 |
| JAI Laxmi Investments Ltd | Wholesale & retail | 2021 |
| Jaiter Ltd | Financial services | 2022 |
| Jakob Holm Limited | Administrative & support | 2026 |
| James Canavan Limited | Arts & recreation | 2013 |
| James Crosby Associates Limited | Professional & scientific | 2016 |
| James Crosby Limited | Hospitality | 2020 |
| James Herbert (Scribble) Limited | Professional & scientific | 1979 |
| Jane Thomson Designs Limited | Professional & scientific | 2003 |
| JBA Project Management Limited | Real estate | 2019 |
| JBL Access Hire Ltd | Administrative & support | 2022 |
| JBL Roofing & Building Maintenance Contractors Ltd | Construction | 2017 |
| Jbrb Estates Ltd | Real estate | 2023 |
| JC30 Promotions Limited | Arts & recreation | 2026 |
| Jcjo Holdings Limited | Information & communication | 2025 |
| JD Jones Properties Limited | Real estate | 2017 |
| JD Pope Investments Ltd | Financial services | 2013 |
| JEN4PROPERTY Limited | Real estate | 2024 |
| Jencol Co Limited | Financial services | 2025 |
| Jenta GP LLP | | 2024 |
| Jenta Investments Limited | Financial services | 2023 |
| Jenta Limited Partnership | | 2023 |
| Jeremy Stack Music Limited | Information & communication | 2020 |
| Jets (U.K.) Limited | Professional & scientific | 1992 |
| JFR Property Limited | Financial services | 2026 |
| JGS Homes Ltd | Professional & scientific | 2009 |
| JJC & MBM Holdings Ltd | Professional & scientific | 2019 |
| JJM Sports Ltd | Arts & recreation | 2024 |
| JKP Communications Ltd | Information & communication | 2025 |
| JLM Bros Consultancy Limited | Professional & scientific | 2024 |
| JML (Financial) Associates Limited | Financial services | 2001 |
| JND Business Limited | Arts & recreation | 2023 |
| Joanna Hudd Limited | Information & communication | 2007 |
| JOE Aribo Limited | Arts & recreation | 2023 |
| JOE42 Limited | Professional & scientific | 2025 |
| John Michael Holdings Ltd | Real estate | 2023 |
| Jojameli Investment Limited | Financial services | 2021 |
| Jojameli Properties Limited | Real estate | 2020 |
| Jones HR Consulting Ltd | Professional & scientific | 2017 |
| Jonny Boom Ltd | Information & communication | 2023 |
| JP Camera Limited | Information & communication | 2006 |
| JPH International Ltd | Real estate | 2024 |
| JPH Property Consultancy Ltd | Real estate | 2024 |
| JPN Properties Limited | Construction | 2021 |
| JR Sparky Ltd | Construction | 2024 |
| JSL Investments Limited | Financial services | 2014 |
| JSL Promotions Limited | Arts & recreation | 2025 |
| Jtlo Limited | Professional & scientific | 2025 |
| JTR Medical Services Ltd | Health & social care | 2011 |
| Juno Private Credit Limited | Financial services | 2025 |
| Jurijs Sell Ltd | Agriculture & fishing | 2024 |
| Juvare Limited | Real estate | 2015 |
| JW Epic Limited | Administrative & support | 2018 |