| IP Softly Limited | Information & communication | 2025 |
| Ironmanager Ltd | Education | 2016 |
| ISMILE1 Ltd | Health & social care | 2025 |
| IT Express Limited | Other services | 2008 |
| IT Managed Services Global Ltd | Information & communication | 2026 |
| Italian DRY Cleaning & Tailoring Ltd | Other services | 2023 |
| Italian Home Styling Limited | Construction | 2014 |
| Itldo Limited | Construction | 2026 |
| ITS IVI Ltd | Hospitality | 2022 |
| ITW CS (UK) Ltd | Administrative & support | 2009 |
| ITW Holdings I Limited | Financial services | 2015 |
| ITW Holdings IV Limited | Financial services | 2015 |
| ITW Holdings VI Limited | Financial services | 2016 |
| ITW Holdings VII Limited | Financial services | 2016 |
| ITW Holdings Viii Limited | Financial services | 2017 |
| ITW Holdings X Limited | Administrative & support | 2020 |
| ITW Holdings XI Limited | Administrative & support | 2020 |
| ITW Limited | Manufacturing | 1956 |
| ITW Pension Funds Trustee Company | Administrative & support | 1992 |
| ITW UK | Professional & scientific | 1998 |
| ITW UK Finance Beta Limited | Other services | 2016 |
| ITW UK Finance Delta Limited | Administrative & support | 2017 |
| ITW UK Finance Gamma Limited | Other services | 2016 |
| ITW UK Finance Limited | Administrative & support | 2015 |
| ITW UK Finance Zeta Limited | Administrative & support | 2020 |
| ITW UK II Limited | Professional & scientific | 2018 |
| Itwr Group Limited | Professional & scientific | 2018 |
| IVI Cafe Limited | Hospitality | 2022 |
| IVI Clinics Limited | Other services | 2021 |
| IVI EAT Ltd | Hospitality | 2022 |
| IVI Fresh Limited | Hospitality | 2022 |
| IVI Holding Limited | Financial services | 2021 |
| IVI Ice Limited | Hospitality | 2022 |
| IVI Invest Ltd | Financial services | 2022 |
| IVI London Limited | Hospitality | 2022 |
| IVI Motorway Services Limited | Hospitality | 2022 |
| IVI Pizza Ltd | Hospitality | 2022 |
| IVI W1 Limited | Hospitality | 2026 |
| IVI Waterfronts Limited | Hospitality | 2016 |
| Ivis Finance Limited | Real estate | 2022 |
| IVN Develop Limited | Hospitality | 2026 |
| IVN OXC Ltd | Hospitality | 2025 |
| IVN OXW Ltd | Hospitality | 2025 |
| IVN RDG Ltd | Hospitality | 2025 |
| IVY & Oak HR Ltd | Administrative & support | 2025 |
| IVY Electric Services Ltd | Construction | 2022 |
| Ivybridge Residents Association (Uxbridge) Limited | Households | 1991 |
| IWO Construction Limited | Construction | 2022 |
| IXN Technologies Limited | Information & communication | 2011 |
| J & D Investments Ltd | Wholesale & retail | 2011 |
| J & S Mccann Consultancy Ltd | Professional & scientific | 2016 |
| J & T Holdings 25 Limited | Real estate | 2025 |
| J . L. Lynford Limited | Hospitality | 2025 |
| J 2 P S Limited | Professional & scientific | 2003 |
| J Gadd Associates Limited | Administrative & support | 2014 |
| J P Singh & Co Limited | Professional & scientific | 2026 |
| J P Tailoring & Menswear Ltd | Wholesale & retail | 2017 |
| J S Harris Limited | Professional & scientific | 2009 |
| J&M Service Limited | Wholesale & retail | 2007 |
| J&P Property Ltd | Real estate | 2025 |
| J.L.E Limited | Hospitality | 2024 |
| JAB Creative Services Limited | Arts & recreation | 2013 |
| Jackson Page Limited | Administrative & support | 2019 |
| Jacl Ltd | Real estate | 2016 |
| Jale’S Aesthetics Limited | Health & social care | 2020 |
| JAM Xandwich Ltd | Real estate | 2017 |
| Jamal Shah Group Limited | Wholesale & retail | 2025 |
| James Norman Business Advisory Limited | Professional & scientific | 2015 |
| Jameson Lodge Management Company Limited | Households | 2010 |
| Jamie Pyatt News Ltd | Information & communication | 2016 |
| Jamie Roche Public Relations Limited | Administrative & support | 1989 |
| Jamil Locum Ltd | Health & social care | 2023 |
| Jango Rolls Limited | Manufacturing | 2021 |
| Jarry Kebab Ltd | Hospitality | 2022 |
| Jass & Buttar Ltd | Wholesale & retail | 2021 |
| Jates Properties Limited | Real estate | 2008 |
| Jatt Limited | Construction | 2023 |
| JAY Squared Ltd | Arts & recreation | 2024 |
| Jaybee Business Support Limited | Real estate | 2012 |
| JB Buildco Ltd | Construction | 2024 |
| JB Windows Limited | Manufacturing | 2018 |
| JC Construction and Security Ltd | Construction | 2024 |
| JCB Solidor Limited | Manufacturing | 2017 |
| JD People & Transformation Consulting Limited | Administrative & support | 2025 |
| Jdfglobal Ltd | Wholesale & retail | 2025 |
| JDS Design and Build Ltd | Construction | 2026 |
| Jdxops Limited | Information & communication | 2025 |
| Jelbel Limited | Administrative & support | 2017 |
| Jellybags LLP | | 2024 |
| JEN Barclay Aesthetics Ltd | Health & social care | 2023 |
| Jeremy's Junction Ltd | Wholesale & retail | 2014 |
| Jermeduk Ltd | Health & social care | 2013 |
| Jetwings Flight Training Ltd | Administrative & support | 2006 |
| Jewell Court Management Company Limited | Households | 2006 |
| Jewels of Africa Ltd | Extraterritorial | 2014 |
| JFB Creative Services Ltd | Information & communication | 2024 |
| JFT1 Ltd | Administrative & support | 2023 |
| JFW Technology Limited | Administrative & support | 2014 |
| JH Healthcare Consulting Ltd | Administrative & support | 2025 |
| Jhja Capital Limited | Hospitality | 2021 |