| Inville Properties Limited | Extraterritorial | 2017 |
| Invision Solutions Ltd | Information & communication | 2024 |
| IOM Padel Ltd | Arts & recreation | 2025 |
| IOT Trading Ltd | Wholesale & retail | 2019 |
| IP Design & Print Limited | Administrative & support | 2009 |
| Ipai Assets Ltd | Information & communication | 2018 |
| Ipex Soft Ltd | Wholesale & retail | 2025 |
| Ipoc Inc Ltd | Information & communication | 2026 |
| Ipsen Walk Ltd | Real estate | 2021 |
| Iqargo Ltd | Professional & scientific | 2014 |
| IQG Ltd | Wholesale & retail | 2024 |
| Ires Hope Initiative CIC | Other services | 2026 |
| Ires Solutions Ltd | Other services | 2025 |
| Irfan Aslam Ltd | Wholesale & retail | 2025 |
| Irfan Sultan Property Co. Limited | Real estate | 2025 |
| IRH Asset Management Ltd | Households | 2020 |
| Iridium Properties Limited | Extraterritorial | 2013 |
| Iris Properties Salford Limited | Real estate | 2013 |
| Iris.Marino Ltd | Wholesale & retail | 2024 |
| IRS Recruitment Holdings Limited | Financial services | 2024 |
| Irwell House Artists' Studios CIC | Arts & recreation | 2017 |
| Irwell Limited | Real estate | 2016 |
| IS Business House Ltd | Financial services | 2010 |
| ISA Global Limited | Construction | 2025 |
| ISA World Services Ltd | Transport & logistics | 2025 |
| Isco Estates Investments Ltd | Real estate | 2025 |
| Isco Estates Ltd | Real estate | 2021 |
| Isco Estates Merseyside Ltd | Real estate | 2025 |
| Isdt Graphene Solutions Limited | Professional & scientific | 2018 |
| Isdt Investment Holdings Limited | Extraterritorial | 2015 |
| Isher Capital Adhki Investments Ltd | Real estate | 2016 |
| Isher Capital First Place Estates Ltd | Real estate | 2013 |
| Isher Capital J11 Ltd | Real estate | 2008 |
| Isher Capital Liberate Ltd | Administrative & support | 2021 |
| Isher Capital RNO10 Group Ltd | Professional & scientific | 2006 |
| Isher Capital RNO2 Ltd | Professional & scientific | 2010 |
| Isher Capital RNO8 Ltd | Professional & scientific | 2010 |
| Isher Capital Sabco 1973 Ltd | Real estate | 2019 |
| Iska Ravenslea Ltd | Real estate | 2025 |
| Isla and Blake Ltd | Wholesale & retail | 2017 |
| Islandbreeze Resources Ltd | Hospitality | 2008 |
| Islavibe Limited | Manufacturing | 2025 |
| Isline Ltd | Real estate | 2025 |
| Islington Mill Arts Club CIC | Arts & recreation | 2008 |
| Islington Plaza Accommodation Nominees Ltd | Extraterritorial | 2021 |
| Islington Plaza Nominees Ltd | Extraterritorial | 2021 |
| Iso-Industries Ltd | Manufacturing | 2023 |
| Isoclean(Uk) Limited | Other services | 2020 |
| Isoulmate Ltd | Hospitality | 2026 |
| ISP Legal Services Limited | Professional & scientific | 2024 |
| ISP Microcaps (U.K.) Limited | Manufacturing | 2004 |
| Issho Design Limited | Professional & scientific | 2026 |
| Issi INK Limited | Arts & recreation | 2023 |
| Italy GAY Travels Ltd | Administrative & support | 2017 |
| ITC MCR Ltd | Other services | 2023 |
| Itdesignstudios Ltd | Wholesale & retail | 2023 |
| Itech Salford Computers Limited | Wholesale & retail | 2017 |
| ITS ALL About YOU Hospitality Ltd | Hospitality | 2024 |
| Itshbstudio Ltd | Information & communication | 2026 |
| ITV 112 Limited | Information & communication | 2018 |
| Ivonmelda Ltd | Other services | 2024 |
| Ivonmeldabynwanne Ltd | Wholesale & retail | 2025 |
| Ivygreen 1990 Limited | Financial services | 2022 |
| IYH Homes Ltd | Real estate | 2018 |
| Izien Solutions Ltd | Administrative & support | 2026 |
| J & E IT Consultancy Limited | Information & communication | 2021 |
| J & T Technical Services Ltd | Administrative & support | 2023 |
| J D Housing Ltd | Real estate | 2019 |
| J Equip Ltd | Wholesale & retail | 2013 |
| J G Bennett Construction Limited | Construction | 2014 |
| J Horwich and Co Ltd | Professional & scientific | 2017 |
| J Hurst Plumbing & Heating Limited | Construction | 2017 |
| J K Lowe Holdings Ltd | Real estate | 2024 |
| J Kennedy Roofing and Property Maintenance Ltd | Construction | 2026 |
| J P Carrington Properties Limited | Real estate | 2026 |
| J Rose Properties Ltd | Real estate | 2013 |
| J S Build & Renovate Limited | Construction | 2019 |
| J T Gillon Distributions Ltd | Mining & quarrying | 2009 |
| J W Welding & Inspection Services Ltd | Manufacturing | 2010 |
| J Zerbib Ltd | Administrative & support | 2019 |
| J&E Real Estate Ltd | Real estate | 2024 |
| J&H Filling Ltd | Wholesale & retail | 2021 |
| J&J Holdings (Bradford) Ltd | Real estate | 2014 |
| J&J Property Projects Ltd | Construction | 2021 |
| J&R North Limited | Manufacturing | 2023 |
| J'Unique Sourcing Solutions Ltd | Households | 2018 |
| J+K Instruments Limited | Manufacturing | 2006 |
| J-Mac Properties Ltd | Real estate | 2023 |
| J. Barnes (Electrical) Limited | | 1960 |
| J. Shine Charities Limited | Health & social care | 1967 |
| J. Soufflet (U.K.) Limited | Professional & scientific | 1974 |
| J.Davidson Hv/Lv Services Ltd. | Construction | 2014 |
| J.J.Oakes & Sons Limited | | 1925 |
| J.L. Kier & Company (London) Limited | Extraterritorial | 1949 |
| J.L.Kier & Company Limited | Extraterritorial | 1932 |
| J.L.R.B. Ltd | Extraterritorial | 2024 |
| J.R Flooring Limited | Construction | 2016 |
| J2J Group Ltd | Professional & scientific | 2026 |
| J2MPOINT Ltd | Wholesale & retail | 2026 |
| JA Legal Consulting Limited | Professional & scientific | 2023 |