| Icortex Limited | Information & communication | 2014 |
| Idol Hands Music, Art and Design Ltd | Wholesale & retail | 2017 |
| IGI Solutions Limited | Professional & scientific | 2001 |
| Ignis Nova Group Ltd | Information & communication | 2026 |
| Ikasu Management Limited | Administrative & support | 2003 |
| Immunopharma Consulting Ltd | Professional & scientific | 2008 |
| Infinite Living Group Limited | Financial services | 2022 |
| Informare Ltd | Professional & scientific | 2008 |
| Infosys Group Ltd | Information & communication | 2025 |
| Innooova Limited | Wholesale & retail | 2024 |
| Inovo Property Ltd | Real estate | 2021 |
| Inside Trax Limited | Wholesale & retail | 2012 |
| Insight Recruitment Group Ltd | Administrative & support | 2019 |
| Insourced Lawyers Limited | Administrative & support | 2015 |
| Insourced Limited | Professional & scientific | 2015 |
| Inspirai Ltd | Wholesale & retail | 2024 |
| Instinct Distribution Limited | Wholesale & retail | 2019 |
| Interior Enterprises Limited | Administrative & support | 1995 |
| International Contemporary Fine Art Limited | Wholesale & retail | 2017 |
| Invision Display Services Limited | Wholesale & retail | 2001 |
| IRC Care Services Limited | Health & social care | 2004 |
| Isotracker Solutions Ltd | Information & communication | 2002 |
| Itworks Computer Systems Limited | Information & communication | 1989 |
| IVR Solutions Limited | Information & communication | 2007 |
| IXD+ Ltd | Information & communication | 2006 |
| J Fritz Ltd | Professional & scientific | 2024 |
| J Painter & Co Limited | Professional & scientific | 2026 |
| J Shelley Electrical Services Limited | Construction | 2014 |
| J Trenchman Limited | Administrative & support | 2017 |
| J W Adams Limited | Manufacturing | 2004 |
| J.A.S Building and Refurbishment Contractors Ltd. | Construction | 2023 |
| Jacky Taylor Limited | Transport & logistics | 2008 |
| Jamax Investments Ltd | Real estate | 2024 |
| James Partridge Limited | Information & communication | 2007 |
| Jarrett Platforms Ltd | Information & communication | 2026 |
| Jasperglen Antiques Limited | Wholesale & retail | 1989 |
| JBJ Media Ltd | Information & communication | 2015 |
| JBM Investment Ltd | Financial services | 2020 |
| JCG Electrical Services Limited | Construction | 2021 |
| Jdms Properties Limited | Real estate | 2013 |
| Jelm Consulting Limited | Administrative & support | 2012 |
| Jewelswift Limited | Real estate | 1985 |
| Jeyes Adhd Services Ltd | Health & social care | 2024 |
| Jezstar Limited | Administrative & support | 2012 |
| JGM Interior Services Ltd | Other services | 2020 |
| JGR Limited | Extraterritorial | 1998 |
| Jgscm Ltd | Professional & scientific | 2024 |
| Jidd Ltd | Administrative & support | 2024 |
| JIM Alexander Consulting Ltd | Professional & scientific | 2024 |
| JJF Hospitality Limited | Administrative & support | 2019 |
| JK Comms Limited | Wholesale & retail | 2010 |
| Jlmc London Limited | Professional & scientific | 2023 |
| JM Servicing Limited | Wholesale & retail | 2023 |
| JMA Psychology Ltd | Health & social care | 2010 |
| JMO Solutions Ltd | Wholesale & retail | 2018 |
| JNR Foodie Ltd | Manufacturing | 2019 |
| John W.Adams(London)Limited | Manufacturing | 1967 |
| Johnny Big Developments Ltd | Construction | 2012 |
| Jones Cove Limited | Extraterritorial | 2018 |
| Joshua James Group Ltd | Financial services | 2024 |
| Joshua James Ltd | Construction | 2021 |
| JP Productions Ltd | Information & communication | 2017 |
| JPB Property Investments Ltd | Real estate | 2025 |
| JPH.308 Ltd | Information & communication | 2008 |
| JPJ Supplies Ltd | Wholesale & retail | 2022 |
| JRC Landscapes Ltd | Construction | 2026 |
| JSO Lewis Consulting Limited | Professional & scientific | 2024 |
| Jumping Jacks Wacc Ltd | Health & social care | 2020 |
| Jupiter Callisto Limited | Other services | 2023 |
| Just Building Contractors Limited | Real estate | 2024 |
| Jwgcatering Ltd | Hospitality | 2024 |
| K & M Brown Limited | Manufacturing | 1999 |
| K Ellis CFO Limited | Professional & scientific | 2024 |
| K J Change Limited | Professional & scientific | 2015 |
| K L Clements Ltd | Professional & scientific | 2025 |
| K M City Electrical Ltd | Construction | 2018 |
| K9TV Limited | Information & communication | 2025 |
| Kaanan Wedding Services Limited | Hospitality | 2019 |
| Kacaribo Limited | Hospitality | 2023 |
| Kalahari Property Investments Limited | Construction | 2024 |
| Karen Kennedy Reiki Limited | Health & social care | 2020 |
| Karugh Assessment, Training & Consultancy Service Ltd | Health & social care | 2015 |
| Kate Grimes Limited | Professional & scientific | 2016 |
| Kate Tulett Art 4 ALL Ltd | Arts & recreation | 2021 |
| Katie Turner Elevate Limited | Professional & scientific | 2025 |
| Kedale Properties Limited | Real estate | 1984 |
| KEE Consulting Limited | Administrative & support | 2013 |
| KEE Partners Ltd | Administrative & support | 2024 |
| Keith Gilbert Ltd | Professional & scientific | 2017 |
| Kelektiv Ltd | Professional & scientific | 2025 |
| Kemico Limited | Wholesale & retail | 2001 |
| Kenley Sports Company,Limited | Real estate | 1903 |
| Kensington Appliances.Co.Uk Ltd | Wholesale & retail | 2017 |
| Kensington Domestic Appliances Limited | Wholesale & retail | 1998 |
| Kent & Surrey Probate Services Ltd | Information & communication | 1984 |
| Kepg Development Ltd | Real estate | 2023 |
| Kevin Travis Creative Ltd | Professional & scientific | 2015 |
| Kilter Ventures Limited | Arts & recreation | 2004 |
| Kindred Robots Ltd | Information & communication | 2026 |
| Kingham Ellis Property Group Limited | Real estate | 2016 |