| Independence Brokerage Services CIC | Information & communication | 2011 |
| Independence Tradespeople Ltd | Administrative & support | 2012 |
| Independent Edition Limited | Arts & recreation | 2016 |
| Infoprive Limited | Other services | 2013 |
| Inglewood Limited | Households | 2000 |
| Inksurance Ltd | Financial services | 2019 |
| Innate Properties Ltd | Real estate | 2022 |
| Innovating Inclusive Minds Ltd | Health & social care | 2024 |
| Innovized Limited | Construction | 2017 |
| Insight People Limited | Professional & scientific | 2026 |
| Inspired Building Projects Limited | Construction | 2012 |
| Insurecon Limited | Financial services | 2018 |
| Interactive Prospect Targeting Limited | Professional & scientific | 2008 |
| Interior Decorative Mouldings Ltd | Construction | 2014 |
| International Watch Dealing Playboy 1 Ltd | Wholesale & retail | 2025 |
| Intersmooth Developments Limited | Construction | 2013 |
| Investible Limited | Financial services | 2024 |
| Inyaface Events Services Ltd | Other services | 2021 |
| Iona Media Limited | Information & communication | 2012 |
| Ireplaceparts Ltd | Wholesale & retail | 2017 |
| Isha Cosmetics Limited | Wholesale & retail | 2017 |
| ISI Secure Ltd | Administrative & support | 2025 |
| Iskayyp Ltd | Information & communication | 2014 |
| Issy London Limited | Wholesale & retail | 2020 |
| IT EYE Limited | Information & communication | 2007 |
| ITC Executive Limited | Administrative & support | 2004 |
| Ivory Crest Ventures Ltd | Manufacturing | 2026 |
| J & Co Contractors Limited | Construction | 2021 |
| J a Watches Limited | Administrative & support | 2018 |
| J E C Sparks Ltd | Energy | 2017 |
| J Hudson & Sons Ltd | Professional & scientific | 2024 |
| J R Blunden Consultants Limited | Construction | 2019 |
| J Transport & Removals Limited | Transport & logistics | 2014 |
| J.Brown Construction Ltd | Construction | 2023 |
| J1 Consultants Ltd | Professional & scientific | 2025 |
| JA Home Solutions Ltd | Professional & scientific | 2012 |
| Jack CAB Ltd | Transport & logistics | 2020 |
| Jackal ENT Limited | Information & communication | 2023 |
| James Jewellery (Surrey) Ltd | Wholesale & retail | 2015 |
| Jarodia Haulage Limited | Transport & logistics | 2025 |
| Jason FRY Associates Ltd. | Information & communication | 2001 |
| Jason Knox-Johnston Limited | Information & communication | 2006 |
| JAW Productions Ltd | Arts & recreation | 2024 |
| Jayprop Limited | Real estate | 2022 |
| Jb-It Resources Limited | Administrative & support | 2017 |
| JBG Ductwork Installations Limited | Construction | 2005 |
| JC Spa Limited | Other services | 2015 |
| JD Musical Services Limited | Arts & recreation | 2021 |
| JDC Advice Ltd | Financial services | 2025 |
| JDL Coding Ltd | Information & communication | 2024 |
| JDM (Blackheath) Limited | Real estate | 2012 |
| JDM (Eltham) Limited | Real estate | 2021 |
| Jeem Solutions Ltd | Professional & scientific | 2022 |
| Jelly BEE Ltd | Real estate | 2025 |
| JET Facilities Ltd | Water & waste | 2014 |
| Jewels by Wheels Limited | Wholesale & retail | 2022 |
| JEZ Cripps Creative Ltd | Professional & scientific | 2026 |
| JFR Facilities Ltd | Administrative & support | 2025 |
| JHS Taxis Ltd | Administrative & support | 2018 |
| JMC Designs Ltd | Professional & scientific | 2025 |
| Jmmj Holdings Limited | Financial services | 2020 |
| Joan's Developments Ltd | Real estate | 2014 |
| JON R Electrical Limited | Construction | 2011 |
| JSH Design London Limited | Wholesale & retail | 2014 |
| JTH Accounting Services Ltd | Professional & scientific | 2022 |
| JTS Ecig Store Ltd | Wholesale & retail | 2015 |
| Juno International Ltd | Professional & scientific | 2022 |
| Juxtadesign Limited | Professional & scientific | 2017 |
| JVI Property Limited | Real estate | 2019 |
| JW GAS Services Ltd | Construction | 2017 |
| JW Property Inc Ltd | Real estate | 2024 |
| JXP Quality Services Limited | Professional & scientific | 2023 |
| K.W.R.A. Limited | Households | 1998 |
| Karsan Limited | Real estate | 2021 |
| Karthi Limited | Professional & scientific | 2010 |
| KAS Build Management Ltd | Professional & scientific | 2018 |
| Kate MCC Faces Ltd | Wholesale & retail | 2022 |
| Kayprop Limited | Real estate | 2016 |
| KBS (Beckenham) Ltd | Construction | 2025 |
| Keeper Security Limited | Administrative & support | 2012 |
| Kensington Physio Ltd | Health & social care | 2016 |
| Kent Mushrooms Limited | Arts & recreation | 1933 |
| Kent PAT Testing Ltd | Manufacturing | 2022 |
| Keston Clinic Ltd | Health & social care | 2024 |
| Kevin Ward IT Services Limited | Information & communication | 2016 |
| Keystone Building Works Ltd | Construction | 2026 |
| Kgvg Consulting Limited | Transport & logistics | 2016 |
| Kindred Family Technologies Ltd | Information & communication | 2026 |
| Kingfisher Clinical Psychology Limited | Health & social care | 2025 |
| Kings Maintenance Limited | Construction | 2014 |
| Kingsmere (Chislehurst) Limited | Hospitality | 2015 |
| Kingsrock Consulting Services Ltd | Administrative & support | 2019 |
| Kirtanharisiya Ltd | Financial services | 2022 |
| Kitoo Ltd | Health & social care | 2013 |
| Kiyu Limited | Health & social care | 2015 |
| Kiyu Properties Limited | Real estate | 2024 |
| Kloudone Consultancy Services Ltd | Information & communication | 2023 |
| KM Controls Limited | Administrative & support | 2009 |
| Koasound Investments Limited | Real estate | 2015 |
| Koncrete Ltd | Construction | 2019 |