| Iconic Plumbing and Heating Ltd | Construction | 2015 |
| IDM Fire Safety Management Limited | Construction | 2016 |
| Ihousei Ltd | Real estate | 2020 |
| Iight Limited | Information & communication | 2024 |
| Iliev Enterprises Ltd | Administrative & support | 2023 |
| Illy Rail Ltd | Construction | 2025 |
| Image Carpentry and Building Ltd | Construction | 2024 |
| Immaculate Garden Ltd | Wholesale & retail | 2018 |
| Impact Construction Projects Ltd | Construction | 2014 |
| IN Defence of Marxism Ltd | Other services | 2012 |
| IN Request Ltd | Other services | 2013 |
| Inclusient Ltd | Professional & scientific | 2025 |
| Indelible Imprint Ltd | Extraterritorial | 2021 |
| Independent Builders Merchant Group Limited | Wholesale & retail | 2018 |
| Independent Media Consultants Ltd | Information & communication | 2021 |
| Independent Roofing Supplies Limited | Wholesale & retail | 2000 |
| Industria Ltd | Wholesale & retail | 2004 |
| Infinity Blue Limited | Real estate | 2018 |
| Infologic Design Limited | Information & communication | 1978 |
| Infrastructure Service Partners Group Limited | Other services | 2019 |
| Ingle Ltd | Information & communication | 2012 |
| Ingrid Gipson Ltd | Education | 2025 |
| Inkforge Ltd | Wholesale & retail | 2026 |
| Innovative Metrics UK Ltd | Professional & scientific | 2020 |
| Inside Matters Counselling Ltd | Health & social care | 2018 |
| Inspirodontics Limited | Health & social care | 2015 |
| Inspium Consulting Limited | Information & communication | 2014 |
| Integral Solution Limited | Information & communication | 2009 |
| Integraplus LLP | | 2020 |
| Intelligent Pathways Limited | Information & communication | 2003 |
| Inter Global NET Store Limited | Manufacturing | 2020 |
| Interbiz Ltd | Professional & scientific | 2019 |
| Interbiz Nominees Ltd | Professional & scientific | 2015 |
| International Blue Ltd | Extraterritorial | 2014 |
| International Wealth Management Limited | Professional & scientific | 2024 |
| International Women in Mining C.I.C. | Other services | 2007 |
| Investment Quotient Ltd | Financial services | 2012 |
| Ip-Ear Limited | Information & communication | 2017 |
| Iris Coffee Ltd | Hospitality | 2025 |
| Isaac's Plumbing and Heating Ltd | Construction | 2025 |
| Itak Holdings Limited | Financial services | 2020 |
| Ivolvy Ltd | Information & communication | 2026 |
| J & L Drainage Ltd | Water & waste | 2019 |
| J C B Estates Limited | Real estate | 2017 |
| J K Neale Limited | Construction | 2016 |
| J M Robinson Holdings Ltd | Wholesale & retail | 2025 |
| J Simpkins Limited | Construction | 2003 |
| J Sims Gardening Ltd | Arts & recreation | 2024 |
| J Sims Karate Limited | Arts & recreation | 2011 |
| J.S.P Landscape and Groundworks Ltd | Construction | 2026 |
| Jake Vine Design Ltd | Professional & scientific | 2021 |
| Jaljo Ltd. | Information & communication | 2018 |
| Jaludasa Sports Limited | Arts & recreation | 2019 |
| James Alexander Heritage Arts C.I.C. | Information & communication | 2026 |
| James Elliott Creative Ltd | Information & communication | 2015 |
| Jamesford Management Consultants Ltd | Professional & scientific | 1995 |
| Jana Nicole Ltd | Wholesale & retail | 2026 |
| Jasar Rail Ltd | Construction | 2021 |
| Jason COE Ltd | Professional & scientific | 2024 |
| Jayscoffee Ltd | Hospitality | 2026 |
| Jazz Lounge Seaside CIC | Arts & recreation | 2020 |
| JCB Home Investments Limited | Real estate | 2020 |
| JCB Resources Ltd | Real estate | 2025 |
| JCB Wayside Ltd | Construction | 2024 |
| JCR Roofing Limited | Construction | 2003 |
| Jetset Family Group Ltd | Professional & scientific | 2021 |
| Jett Group Ltd | Real estate | 2020 |
| Jett Software Solutions Ltd | Information & communication | 2025 |
| JHJ Services Ltd | Professional & scientific | 2014 |
| Jigsaw Music Group Ltd | Information & communication | 2017 |
| Jijies Rest Ltd | Agriculture & fishing | 2019 |
| Jjam Pro Limited | Construction | 2025 |
| JK Fire and Securty Ltd | Administrative & support | 2026 |
| JLA Bookkeeping & Accounts Ltd | Professional & scientific | 2023 |
| JMR Technology Holdings Limited | Professional & scientific | 2024 |
| Jolly Cleaners Ltd | Administrative & support | 2024 |
| Jones Signalling Solutions Limited | Construction | 2015 |
| Jrgb Limited | Wholesale & retail | 2017 |
| JRP Premium Cleaning Services Ltd | Administrative & support | 2025 |
| JTP Fitness Ltd | Extraterritorial | 2016 |
| Juicy Coffee Co. Ltd | Hospitality | 2025 |
| Jun's Incorporated Ltd | Professional & scientific | 2024 |
| Junction House Mortgages Ltd | Financial services | 2026 |
| Jwec Ltd | Construction | 2019 |
| Jwesty Designs Ltd | Professional & scientific | 2017 |
| K.N.R. Logistics Limited | Transport & logistics | 2002 |
| K2 Indian Restaurant Ltd | Hospitality | 2011 |
| Kaebo Graphics Limited | Professional & scientific | 2018 |
| Kaela DE Jean Limited | Other services | 2012 |
| Kamal Fernandez Dog Training Ltd | Education | 2020 |
| Kancelaria PAR LEX Ltd | Professional & scientific | 2023 |
| Kancelaria Prawna EX Lege Ltd | Wholesale & retail | 2022 |
| Kannadigaru UK Community Interest Company | Education | 2008 |
| Karen a Turner Ltd | Other services | 2025 |
| Katalin Consulting Ltd | Professional & scientific | 2017 |
| Kate Scrace Consulting Ltd | Professional & scientific | 2016 |
| Kathryn Trower Limited | Extraterritorial | 2015 |
| KAY Publishing Ltd | Information & communication | 2009 |
| KB Couriers South East Ltd | Transport & logistics | 2020 |
| KBC Law Ltd | Professional & scientific | 2023 |