| Isaila Property Ltd | Real estate | 2025 |
| Isca Homes Limited | Real estate | 2024 |
| Iserv Global PVT Ltd | Information & communication | 2024 |
| Ishizue Ltd | Construction | 2026 |
| Islam Mohbubara AID Ltd | Other services | 2020 |
| Island Food & Wine Ltd | Wholesale & retail | 2025 |
| Island Village Family Centre Ltd | Health & social care | 2023 |
| Island Way Barbers Ltd | Other services | 2024 |
| Isle of Good Ltd | Manufacturing | 2025 |
| Isle of Vapes Ltd | Wholesale & retail | 2018 |
| Ismart Vending Limited | Wholesale & retail | 2025 |
| Ismet T Limited | Wholesale & retail | 2019 |
| Ismot ARA Accountancy Ltd | Professional & scientific | 2023 |
| Isoundproequipments Limited | Manufacturing | 2021 |
| Istanbul Auto Services Ltd | Wholesale & retail | 2020 |
| Istanbul Food Centre Limited | Other services | 2017 |
| Istanbul Fruit and VEG Ltd | Wholesale & retail | 2024 |
| Istanbul Property Limited | Real estate | 2025 |
| Istoo Limited | Construction | 2018 |
| IT Outsourcing Consultancy Ltd | Information & communication | 2013 |
| IT Simplified (UK) Ltd | Information & communication | 2014 |
| IT Starts With a Smile Ltd | Real estate | 2024 |
| It&Ly Hair & Beauty Limited | Wholesale & retail | 1993 |
| Italian Marble Installation Company Limited | Construction | 1999 |
| Itara UK Ltd | Wholesale & retail | 2020 |
| Itex IT Ltd | Information & communication | 2018 |
| ITI Fashions Consultancy Ltd | Wholesale & retail | 2019 |
| Ivas Group Ltd | Construction | 2015 |
| Iveybeautyy Limited | Other services | 2023 |
| IVJ Consulting Limited | Information & communication | 2015 |
| Ivory Corporate Care Ltd | Administrative & support | 2025 |
| Ivory Event Decorations UK Ltd | Other services | 2017 |
| Ivory Property London Ltd | Real estate | 2021 |
| Ivory Services Ltd | Hospitality | 2022 |
| IVS Finance Limited | Arts & recreation | 2026 |
| IVY June Limited | Other services | 2022 |
| IVY London Properties Ltd | Real estate | 2024 |
| IX 100 Ltd | Administrative & support | 2020 |
| Ixia Clinical Limited | Professional & scientific | 2023 |
| IXM Ltd | Manufacturing | 2000 |
| IYD Investments Limited | Construction | 2024 |
| Iykecha Ltd | Construction | 2022 |
| Iz&Ka Investment Ltd | Wholesale & retail | 2025 |
| Izaraz Ltd | Wholesale & retail | 2025 |
| Izlem Ltd | Manufacturing | 2021 |
| Izmir Properties Ltd | Real estate | 2025 |
| Izmr Ltd | Hospitality | 2025 |
| J & a Utilities Limited | Construction | 2009 |
| J & D Express Ltd | Transport & logistics | 2023 |
| J & H Brickwork Contractors Limited | Wholesale & retail | 1987 |
| J & J Babywear Boutique Limited | Extraterritorial | 2019 |
| J & K L Ltd | Financial services | 2019 |
| J & M Nails Spa Limited | Other services | 2023 |
| J & MAY Ltd | Real estate | 2007 |
| J & PP Consulting Limited | Real estate | 2005 |
| J & S Security Ltd | Administrative & support | 2018 |
| J and KW Properties Ltd | Real estate | 2016 |
| J B Treeworks Ltd | Agriculture & fishing | 2015 |
| J C Walker Butchers Ltd | Wholesale & retail | 2019 |
| J Green Cars Ltd | Wholesale & retail | 2024 |
| J H B Enfield Limited | Professional & scientific | 1998 |
| J J Food Service Holdings Limited | Real estate | 2000 |
| J JO Beauty Limited | Wholesale & retail | 2021 |
| J Marsh Electrical Ltd | Construction | 2015 |
| J P Kallar Limited | Hospitality | 2021 |
| J R E K Property Ltd | Real estate | 2018 |
| J Raymond Welch Surveyors Ltd | Professional & scientific | 2013 |
| J Van Vliet ( Southampton ) Ltd | Wholesale & retail | 2009 |
| J Van Vliet (Ashton) Ltd | Wholesale & retail | 2009 |
| J Van Vliet (Birmingham) Limited | Wholesale & retail | 2008 |
| J Van Vliet (Derby) Ltd | Wholesale & retail | 2001 |
| J Van Vliet (Glasgow) Limited | Wholesale & retail | 2004 |
| J Van Vliet (Heathrow) Ltd | Wholesale & retail | 2005 |
| J Van Vliet (Manchester) Limited | Wholesale & retail | 2006 |
| J Van Vliet (Northampton) Limited | Wholesale & retail | 2000 |
| J&B Butcher Grocery Limited | Wholesale & retail | 2021 |
| J&D Collective Co. Ltd | Wholesale & retail | 2026 |
| J&H Cars Limited | Wholesale & retail | 2026 |
| J&J Dibb Ltd | Wholesale & retail | 2018 |
| J&S Cleaningcompany Limited | Administrative & support | 2025 |
| J&W Maintenance Services Ltd | Construction | 2019 |
| J'Aide Ltd | Administrative & support | 2025 |
| J. Browne Property Holdings Limited | Administrative & support | 2008 |
| J. Hanley Builders Limited | Construction | 1978 |
| J. Mcgowan Services Limited | Other services | 2016 |
| J. Van Vliet (Gateshead) Ltd | Wholesale & retail | 2009 |
| J. Van Vliet (Nottingham) Limited | Wholesale & retail | 2014 |
| J. Van Vliet (Stoke on Trent) Ltd | Wholesale & retail | 2011 |
| J. Van Vliet C&C Facilities Ltd | Professional & scientific | 2009 |
| J. Van Vliet London Cash & Carry Limited | Wholesale & retail | 1994 |
| J.A.Bunyan Limited | Professional & scientific | 1956 |
| J.Buffong Ltd | Information & communication | 2025 |
| J.E.Wang London Ltd | Professional & scientific | 2017 |
| J.F.Kelly Electrical Limited | Construction | 2011 |
| J.H & Sons Estates Ltd | Real estate | 2019 |
| J.J Construction & Building Ltd | Construction | 2019 |
| J.Mawunyo Ltd | Financial services | 2025 |
| J.S Private Limited | Wholesale & retail | 2025 |
| J.Van Vliet S.A. Limited | Wholesale & retail | 1999 |
| J3 Autos Ltd | Wholesale & retail | 2025 |