| Investment Home Lets Ltd | Real estate | 2024 |
| Invicta Care and Training Ltd | Health & social care | 2014 |
| Invictus Facilities and Management Ltd | Real estate | 2018 |
| Iolandacouriers Ltd | Transport & logistics | 2019 |
| Ionetsecure Limited | Information & communication | 2024 |
| Ionut Rendering Ltd | Construction | 2025 |
| Iplus Tech Ltd | Information & communication | 2018 |
| IPN Property Limited | Real estate | 2013 |
| Ipro Chauffeur Ltd | Transport & logistics | 2021 |
| Ipro Cleaning Solutions Limited | Administrative & support | 2025 |
| IQ Global Travel Ltd | Administrative & support | 2021 |
| IQ5 Ltd | Construction | 2018 |
| Iqubal Singh Ltd | Construction | 2025 |
| IRC Design Ltd | Professional & scientific | 2004 |
| Irepairphonesuk Limited | Other services | 2021 |
| Irfa Catering Ltd | Hospitality | 2021 |
| Ironclad Labs Ltd | Information & communication | 2023 |
| Ironing BOY Ltd | Other services | 2025 |
| Ironman Steel Limited | Extraterritorial | 2015 |
| Ironstead Systems Limited | Information & communication | 2025 |
| IS Ameen Limited | Professional & scientific | 2004 |
| Iscp Consulting Limited | Information & communication | 2021 |
| Ishaaq Ltd | Wholesale & retail | 2025 |
| Ishha Home Care Ltd | Health & social care | 2025 |
| Island MAS Limited | Arts & recreation | 2018 |
| Island Tastes Limited | Wholesale & retail | 2020 |
| Island Wellness Ltd | Other services | 2023 |
| Ismart GIS Ltd | Information & communication | 2015 |
| Isobel Advertising Limited | Professional & scientific | 2003 |
| Isobel Group Limited | Financial services | 2015 |
| Isobel Worldwide Limited | Professional & scientific | 2015 |
| Issy Logistics Ltd | Transport & logistics | 2018 |
| Istante Properties Limited | Real estate | 2020 |
| Istante Properties London Limited | Real estate | 2024 |
| IT Design & Solutions Ltd | Information & communication | 2015 |
| IT for YOU Limited | Information & communication | 2012 |
| IT One Solutions Ltd | Information & communication | 2012 |
| IT Project Pulse Limited | Professional & scientific | 2024 |
| IT4U Consultancy Limited | Information & communication | 2015 |
| ITA Consulting Ltd | Information & communication | 1997 |
| Itacumen Limited | Wholesale & retail | 2016 |
| Itrvg Ltd | Real estate | 2021 |
| IVB Construct Services Ltd | Construction | 2026 |
| Iver Leaf Developments Limited | Construction | 2022 |
| Iver Leaf Limited | Wholesale & retail | 2019 |
| Ivivid Ltd | Construction | 2024 |
| Ivory Books Ltd | Information & communication | 2021 |
| IVY Cottage Estates Limited | Real estate | 2025 |
| Ivybridge Productions Ltd | Information & communication | 2022 |
| Iwan Williams Limited | Professional & scientific | 2011 |
| Iwantitnow Ltd | Wholesale & retail | 2015 |
| Iwenesu Ltd | Wholesale & retail | 2025 |
| IY Talks Ltd | Education | 2024 |
| Iyla Clinic Ltd | Health & social care | 2026 |
| Izhaan Food Point Ltd | Hospitality | 2023 |
| Izzah Food Corner Ltd | Hospitality | 2024 |
| J & B Care Home Limited | Health & social care | 2018 |
| J & H Builders Limited | Construction | 2015 |
| J & N Real Estates Ltd | Real estate | 2018 |
| J a Barber Limited | Other services | 2018 |
| J a Locum Solutions Limited | Administrative & support | 2010 |
| J Aaron Developments Ltd | Construction | 2024 |
| J Austin Media Ltd | Professional & scientific | 2022 |
| J B N Building Services Limited | Construction | 2013 |
| J Chomko Ceilings & Partitions Ltd | Construction | 2008 |
| J Desai Consultants Ltd | Professional & scientific | 2025 |
| J Dhillon Transport Ltd | Transport & logistics | 2015 |
| J K Demolition Ltd | Construction | 2025 |
| J Kennedy Haulage Limited | Transport & logistics | 2008 |
| J Komor Technology Ltd | Manufacturing | 2021 |
| J M Decorating Services Ltd | Construction | 2017 |
| J N FOX and Sons UK Limited | Manufacturing | 2003 |
| J P Traders Ltd | Wholesale & retail | 2013 |
| J R D Propstores Ltd | Professional & scientific | 2025 |
| J Saward Services Ltd | Arts & recreation | 2018 |
| J Simpson Residential Limited | Real estate | 2016 |
| J VEE Services Ltd | Construction | 2018 |
| J&A Optical Consultancy Limited | Health & social care | 2022 |
| J&B Honor Group Ltd | Wholesale & retail | 2024 |
| J&C Tech Ltd | Wholesale & retail | 2026 |
| J&R Co London Ltd | Construction | 2025 |
| J&S Hairdressing Services Limited | Other services | 2015 |
| J-K Estate Agents Limited | Real estate | 2002 |
| J.A.B. Carpentry Ltd | Construction | 2019 |
| J.B. Robert Advisory Ltd | Professional & scientific | 2026 |
| J.J. Hills Rigging and Construction Limited | Construction | 2025 |
| J.O.S Invest Limited | Construction | 2020 |
| J.V.C WET Waste Ltd | Water & waste | 2021 |
| J9SH Ltd | Education | 2024 |
| Jack Stores Limited | Wholesale & retail | 2017 |
| Jacks Salon Ltd Ltd. | Other services | 2017 |
| Jacobs Global Consulting Limited | Information & communication | 2019 |
| JAD Business Developments Limited | Real estate | 2022 |
| JAD Mortgages Ltd | Financial services | 2025 |
| Jadore Hair Boutique Limited | Other services | 2024 |
| Jafar Beauty Clinic Limited | Other services | 2015 |
| Jaffna Electro Tech Limited | Manufacturing | 2026 |
| Jaggi Supermarket Ltd | Wholesale & retail | 2020 |
| Jags K Ltd | Information & communication | 2017 |
| Jainal Property Ltd | Real estate | 2026 |