| Interasia Limited | Wholesale & retail | 2007 |
| Intercept Cabling Limited | Information & communication | 2010 |
| Intereurope (Furniture) Limited | Wholesale & retail | 2006 |
| Interior Screed Group Ltd | Professional & scientific | 2010 |
| International Assoc. for Rewind Trauma Therapy Ltd | Professional & scientific | 2024 |
| International Society for Trenchless Technology(The) | Professional & scientific | 1986 |
| Interseeds Limited | Wholesale & retail | 2024 |
| Intransic Limited | Real estate | 2006 |
| INV Platforms Limited | Other services | 2025 |
| Investhom Limited | Financial services | 2015 |
| Invicta Finance Ltd | Financial services | 2024 |
| IO Studios Ltd | Information & communication | 2008 |
| Iona Testing Consultancy Limited | Professional & scientific | 2019 |
| IP North Limited | Professional & scientific | 2021 |
| IP Place Limited | Wholesale & retail | 2017 |
| Ipiper Services Ltd | Information & communication | 2023 |
| Iplanworld Limited | Information & communication | 2019 |
| Irvine Transport Services Ltd | Transport & logistics | 2026 |
| Irving David Limited | Professional & scientific | 2019 |
| IS Dynamics Ltd | Manufacturing | 2025 |
| Isaac Orthopaedics Limited | Real estate | 2016 |
| ISG (International) Limited | Wholesale & retail | 2010 |
| ISG FM Ltd | Administrative & support | 2026 |
| Island Quay Management Limited | Real estate | 1985 |
| Istanbul Bazaar Limited | Wholesale & retail | 2018 |
| Italysua Ltd | Hospitality | 2024 |
| Iteamco Ltd. | Professional & scientific | 2015 |
| Izone Driver Performance Limited | Arts & recreation | 2010 |
| J & H Maintenance & Tree Surgery Limited | Administrative & support | 2025 |
| J & S Diamond Limited | Professional & scientific | 2012 |
| J a Wright Electrical Ltd | Other services | 2016 |
| J B SEE Limited | Professional & scientific | 2025 |
| J Cubitt Events & Production Ltd | Administrative & support | 2026 |
| J F Building Contractors Limited | Construction | 2014 |
| J Hogan and SON Limited | Manufacturing | 2017 |
| J Howson Ltd | Administrative & support | 2025 |
| J M Brad Management Ltd | Real estate | 2018 |
| J M Kent Limited | Other services | 2002 |
| J Parnaby Partners Limited | Professional & scientific | 2010 |
| J S Robinson Builders Ltd | Construction | 2007 |
| J Sykes Consultancy Ltd | Administrative & support | 2020 |
| J W Agencies Limited | Wholesale & retail | 2004 |
| J. Cameron & Associates LLP | | 2025 |
| J. Gisbourne Commercials Limited | Wholesale & retail | 2002 |
| J. Hopson Construction & Property Maintenance Ltd | Administrative & support | 2024 |
| J. Kenney-Herbert Limited | Health & social care | 2010 |
| J. R. Wootton Limited | Construction | 2002 |
| J.A. and S.A. Wilson Property Ltd. | Real estate | 2022 |
| J.B. Group Limited | Construction | 1999 |
| J.D Wilcox CAD Services Limited | Professional & scientific | 2015 |
| J.H. Thorp Limited | Real estate | 2000 |
| J.S.Moberley Properties Ltd | Real estate | 2025 |
| Jach & Co. Limited | Construction | 2001 |
| Jackson RP Ltd | Public administration | 2021 |
| Jacqueline Anne Graves Limited | Extraterritorial | 2024 |
| Jacqueline Louise Bridal Ltd | Wholesale & retail | 2020 |
| Jade Holdings Limited | Real estate | 2021 |
| Jadeon Software Ltd | Information & communication | 2023 |
| Jakeman Enterprises Limited | Real estate | 2008 |
| Jalima Consulting Ltd | Other services | 2017 |
| JAM JAR Publishing Limited | Information & communication | 2024 |
| James C COX Ltd | Real estate | 2008 |
| James Calado Motorsport Ltd | Arts & recreation | 2015 |
| James Peterson Investments Limited | Real estate | 2023 |
| Jamie Francis Limited | Arts & recreation | 2016 |
| Jamie Mccreghan Ltd | Health & social care | 2014 |
| Jane Hayward Services Ltd | Education | 2025 |
| Jane Investments Limited | Real estate | 2018 |
| Jane Scrivner Limited | Extraterritorial | 2004 |
| Japonica Pride Limited | Households | 2014 |
| Jarec Investments Ltd | Construction | 2021 |
| Jasmine Cottage Limited | Hospitality | 2023 |
| Java Portfolio Management Limited | Construction | 2022 |
| Jayne Frost ISW Services Ltd | Health & social care | 2025 |
| JC 29 Limited | Information & communication | 2005 |
| JC 41 Ltd | Information & communication | 2017 |
| JCE 3D Design Ltd | Professional & scientific | 2024 |
| JCS EW Holdco Ltd | Real estate | 2025 |
| JCS MW Holdco Ltd | Real estate | 2025 |
| JD Structural Engineering Ltd | Professional & scientific | 2023 |
| JDA Estate Services Limited | Administrative & support | 2014 |
| JDH Music Services Ltd | Information & communication | 2024 |
| JDM Advisory Ltd | Professional & scientific | 2022 |
| Jemcas Holdings Limited | Real estate | 2016 |
| Jennings Letting Ltd | Real estate | 2025 |
| Jericho Law Ltd | Professional & scientific | 2022 |
| Jerry Chung Design Limited | Professional & scientific | 2026 |
| JET Escapes Ltd | Administrative & support | 2009 |
| Jetex Exhausts Limited | Wholesale & retail | 1986 |
| Jfsw Four Limited | Construction | 2023 |
| Jfsw One Limited | Construction | 2019 |
| Jfsw Three Limited | Real estate | 2021 |
| Jfsw Two Limited | Construction | 2019 |
| JG Physique Limited | Arts & recreation | 2019 |
| JG Property Holdings (UK) Limited | Financial services | 2022 |
| JIM Jams Children’S Books Limited | Information & communication | 2025 |
| JJ Driving Tuition Limited | Education | 2024 |
| JJM Physiotherapy Limited | Health & social care | 2020 |
| Jjnb Solutions Limited | Information & communication | 2023 |
| Jjwtechnicalsolutions Limited | Manufacturing | 2022 |