| Intellianj Limited | Information & communication | 2019 |
| Intelligent Engagement Limited | Professional & scientific | 2020 |
| Intelligent Resources and Services Limited | Extraterritorial | 2015 |
| Intergrated Security Systems Limited | Administrative & support | 2008 |
| Intermobel Holdings Limited | Real estate | 1971 |
| International Circuits Limited | Administrative & support | 1972 |
| International Distribution Incubator (I.D.I) Ltd | Information & communication | 2020 |
| International Forensic Sciences Limited | Professional & scientific | 2020 |
| INV Property Consultants Limited | Administrative & support | 2013 |
| Iosis Clinic (Godalming) Limited | Health & social care | 2011 |
| Iron Forests Consulting Ltd | Information & communication | 2023 |
| Ironstone Surrey Ltd | Construction | 2025 |
| Iroq Ltd | Wholesale & retail | 2024 |
| IS FD Limited | Professional & scientific | 2009 |
| Isaacxed Limited | Construction | 2026 |
| Isla Properties Limited | Real estate | 2014 |
| Iunctura Business Services Ltd | Professional & scientific | 2024 |
| IVY Castle Investments Limited | Real estate | 2019 |
| IVY House Learning Limited | Education | 2017 |
| IVY House London Ltd | Education | 2018 |
| IVY Medical Chemicals Development Limited | Professional & scientific | 1997 |
| J & N Estates (Surrey) Ltd | Hospitality | 2022 |
| J and C Construction Services Limited | Construction | 2022 |
| J K Heat Pump Services Limited | Administrative & support | 2016 |
| J K UK Store Ltd | Wholesale & retail | 2025 |
| J M D Aerospace Ltd | Manufacturing | 2019 |
| J Morley Agencies Ltd | Wholesale & retail | 2022 |
| J P Coles and Partners LP | | 2019 |
| J&B Arora Ltd | Transport & logistics | 2024 |
| J&L Health Ltd | Health & social care | 2019 |
| J&Lt Management Limited | Professional & scientific | 2023 |
| J.M Waste Management & Services Ltd | Wholesale & retail | 2025 |
| J.O. Harris Holdings Limited | Real estate | 1965 |
| J.Weatherbed Limited | Manufacturing | 2011 |
| Jacob Grace Limited | Professional & scientific | 2018 |
| Jago K Nominee Limited | Professional & scientific | 2025 |
| James & Jake Ltd | Wholesale & retail | 2015 |
| James Barnett Creates Limited | Information & communication | 2025 |
| James Etherington Associates Limited | Construction | 1945 |
| Jane Drapper Taxation Services Limited | Professional & scientific | 2024 |
| Janus Management Consulting Limited | Professional & scientific | 2005 |
| Jason Weir Landscaping & Stonework Limited | Administrative & support | 2019 |
| JAT Garden Services Ltd | Administrative & support | 2025 |
| JBP London Limited | Manufacturing | 2023 |
| Jctp Shows Limited | Arts & recreation | 2021 |
| Jctp Spring Limited | Arts & recreation | 2021 |
| JDS Homes & Lettings Limited | Construction | 2022 |
| JDS Management & Consulting Limited | Professional & scientific | 2022 |
| Jegmw Consulting Ltd | Professional & scientific | 2025 |
| Jendes Advisers Limited | Financial services | 2015 |
| Jennifer White Ltd | Other services | 2003 |
| Jewelled Limited | Manufacturing | 2001 |
| Jewelledagain Ltd | Wholesale & retail | 2024 |
| JG Kitchen Co. Ltd | Hospitality | 2026 |
| JGB2 Limited | Arts & recreation | 2024 |
| JGR Developments Surrey Limited | Construction | 2017 |
| Jhihj Ltd | Information & communication | 2025 |
| Jica Beauty Products Limited | Wholesale & retail | 1978 |
| JLC Homes Ltd | Real estate | 2010 |
| JLJ Consulting Ltd | Professional & scientific | 2025 |
| Jmdandco.Com Limited | Professional & scientific | 2002 |
| JML Business Services Limited | Professional & scientific | 1997 |
| JMS Resources HQ Limited | Professional & scientific | 2014 |
| JN Tech Solutions Limited | Information & communication | 2014 |
| JNN Ltd | Wholesale & retail | 2025 |
| JO88 Limited | Arts & recreation | 2024 |
| Joalan Limited | Construction | 2005 |
| JOB and Finish Ltd | Construction | 2020 |
| JOE Court Forestry Ltd | Agriculture & fishing | 2013 |
| Joe's Electrical Ltd | Construction | 2025 |
| Joel Stevens Joinery & Carpentry Limited | Construction | 2024 |
| Joelither Limited | Information & communication | 2022 |
| John Crawford Limited | Administrative & support | 2023 |
| John Jeffery Consulting Limited | Professional & scientific | 2009 |
| John Kimbell Limited | Professional & scientific | 2025 |
| Jonathan Church Theatre Productions Limited | Arts & recreation | 2019 |
| Jones and Sons Bespoke Removals Ltd | Transport & logistics | 2025 |
| Jones and Sons Removals Ltd | Transport & logistics | 2024 |
| Jordans Garage Limited | Wholesale & retail | 2002 |
| Joshi Sisters Ltd | Professional & scientific | 2023 |
| Joule Inc Ltd | Professional & scientific | 2023 |
| Joyfull Greens CIC | Education | 2024 |
| Jozi Sun Investments Limited | Financial services | 2025 |
| JP Building Consultancy Ltd | Professional & scientific | 2020 |
| JP Renewable Europe Company Limited | Financial services | 2018 |
| JP Yachting LLP | | 2022 |
| Jpseven Limited | Administrative & support | 2017 |
| JRC Cooper Limited | Professional & scientific | 2012 |
| Jrmoss Limited | Professional & scientific | 2024 |
| Jt.Prime Shine Solutions Ltd | Administrative & support | 2025 |
| Jubilee Cleaners Ltd | Administrative & support | 2003 |
| Juicy Energy Ltd | Information & communication | 2021 |
| Julian Ladd Solutions Limited | Professional & scientific | 2022 |
| Julian Oakey Limited | Financial services | 2013 |
| Jump Sideways Ltd | Information & communication | 2017 |
| Juniverse Ltd | Information & communication | 2025 |
| Jurassic Sea Farms Ltd | Wholesale & retail | 2018 |
| Just Look London Ltd | Wholesale & retail | 2021 |
| Justin Live Limited | Arts & recreation | 2025 |
| K L H Brand Advocates Limited | Administrative & support | 2011 |