| Immaculate Cleaning Service Ltd | Wholesale & retail | 2019 |
| Impact Community Housing Ltd | Households | 2023 |
| Impact Project College Ltd | Education | 2021 |
| Impact Project Solutions Ltd | Health & social care | 2014 |
| IN OUT Property Services Ltd | Real estate | 2021 |
| IN9 Research and Development Ltd | Professional & scientific | 2024 |
| Incircity Limited | Information & communication | 2017 |
| Indian National Students Association (Insa-Uk) CIC | Administrative & support | 2023 |
| Indirect Solutions Ltd | Administrative & support | 2023 |
| Indulgence Beauty Salons Limited | Other services | 2012 |
| INFIN8 Potential Ltd | Professional & scientific | 2023 |
| Infonica Limited | Wholesale & retail | 2017 |
| Information Security Services Ltd | Information & communication | 2020 |
| Ingram Building and Electrical Contractors Limited | Construction | 2023 |
| Init Networks Limited | Information & communication | 2009 |
| INK Paradise Ltd | Other services | 2017 |
| Inksmiths of London Limited | Other services | 2009 |
| Innergy 212 Ltd | Wholesale & retail | 2025 |
| Inprop Management Ltd | Real estate | 2023 |
| Install Solutions Limited | Construction | 2024 |
| Intafinance Limited | Professional & scientific | 2010 |
| Intelectrical Solutions Ltd | Construction | 2019 |
| Intelli Data & AI Works Ltd | Information & communication | 2026 |
| Inter Decor Ltd | Construction | 2013 |
| Intercybersec Technologies Limited | Information & communication | 2019 |
| Interior Design & Innovation Ltd | Other services | 2025 |
| Intermix Group Limited | Financial services | 2025 |
| Intermix Management Limited | Construction | 2020 |
| Intermix Properties Limited | Real estate | 2025 |
| International Mineral Resources Agromineral Sudan Ltd | Mining & quarrying | 2026 |
| International Properties Solution Ltd | Households | 2023 |
| Interway Computer Consultants Limited | Information & communication | 1998 |
| Interxpress Colete Ltd | Transport & logistics | 2020 |
| Into Info Ltd | Information & communication | 2019 |
| Invicta Properties Sidcup Limited | Real estate | 2021 |
| Ionyx Properties Limited | Real estate | 2019 |
| Ionyx Technologies Limited | Information & communication | 2014 |
| Iovdan Building Ltd. | Construction | 2012 |
| Ip-Advisors Limited | Other services | 2025 |
| Irish Community Services | Health & social care | 1999 |
| IRW Trading Ltd | Wholesale & retail | 2021 |
| Ishanth Ltd | Information & communication | 2024 |
| Isite Facilities Ltd | Real estate | 2014 |
| ISLAND1623 Limited | Professional & scientific | 2025 |
| IT Arch Solutions Ltd | Information & communication | 2021 |
| IT Transmuter Cloud Force Limited | Information & communication | 2017 |
| Italian DRY Cleaners Ltd | Other services | 2022 |
| Itsco.Construction Ltd | Construction | 2024 |
| Ivan DE VÉ Limited | Real estate | 2025 |
| Ivanz Limited | Construction | 2025 |
| Ivory Aura Ltd | Financial services | 2025 |
| J & a London Ltd | Real estate | 2012 |
| J & L Specialist Fixing Ltd | Construction | 2006 |
| J & S Dryliners Ltd | Construction | 2022 |
| J Bains Construction Ltd | Construction | 2014 |
| J Engineering Services Ltd | Health & social care | 2019 |
| J Humber Properties Ltd | Real estate | 2023 |
| J R Heating & Plumbing Solutions Limited | Construction | 2013 |
| J Star Nails Ltd | Other services | 2019 |
| J Virdi Financial Consultancy Ltd. | Professional & scientific | 2012 |
| J W Scudder Roofing Limited | Construction | 2014 |
| J&C K Investments Limited | Real estate | 2026 |
| J. Walpole Solutions Limited | Professional & scientific | 2018 |
| J.A.B. Properties & Investments Limited | Real estate | 2022 |
| J.A.M Medical Ltd | Health & social care | 2020 |
| JAA Consulting Services Ltd | Professional & scientific | 2025 |
| Jabi Ltd | Wholesale & retail | 2023 |
| JAC Jossa School of Performing Arts Ltd | Arts & recreation | 2019 |
| Jack Maroni Limited | Arts & recreation | 2024 |
| Jagg Transport Ltd | Transport & logistics | 2019 |
| Jaisantri Ltd | Real estate | 2022 |
| Jaitash Investments Limited | Arts & recreation | 2025 |
| Jalapapple Limited | Hospitality | 2017 |
| JAM Tech Consulting Ltd | Information & communication | 2013 |
| JAM Tech Properties Ltd | Real estate | 2022 |
| Jane Allington Ltd | Health & social care | 2013 |
| Janstds Limited | Information & communication | 2016 |
| Jasmine City Stay Limited | Real estate | 2024 |
| JAY Unit Ltd | Construction | 2026 |
| Jay.Edu Ltd | Education | 2026 |
| Jayce Safe Services (UK) Limited | Health & social care | 2013 |
| Jaylaad Solutions Ltd | Real estate | 2024 |
| JB Ductwork Solutions Ltd | Construction | 2016 |
| JBR Drylining Limited | Construction | 2019 |
| JE4US Ltd | Real estate | 2024 |
| Jeeves Plumbing & Heating Ltd | Construction | 2016 |
| Jefferson Wolfe Consulting Ltd | Professional & scientific | 2024 |
| Jelly Music Ltd | Education | 2024 |
| Jeppco International Ltd | Manufacturing | 2021 |
| Jesugem UK Limited | Administrative & support | 2018 |
| JET2WASH Ltd | Administrative & support | 2020 |
| JFB Mckellar Limited | Information & communication | 2017 |
| JFL Motorcycle Ltd | Wholesale & retail | 2022 |
| JG Ents Ltd | Arts & recreation | 2023 |
| JG Research & Consulting Limited | Professional & scientific | 2022 |
| JH Cleaning Limited | Administrative & support | 2022 |
| JHJ UK Facilities Limited | Other services | 2019 |
| Jhmf Limited | Administrative & support | 2021 |
| Jiddak Limited | Wholesale & retail | 2016 |
| Jilada Limited | Transport & logistics | 2024 |