| Instructive Business Limited | Professional & scientific | 2025 |
| Integrity Fitness Limited | Professional & scientific | 2024 |
| Intellectual Minds Limited | Information & communication | 2023 |
| Intellex Consulting Services Limited | Professional & scientific | 2007 |
| Intellex Real Estate Limited | Real estate | 2025 |
| Intelli Consultants Ltd | Professional & scientific | 2008 |
| Intellix (Holdings) Limited | Wholesale & retail | 2019 |
| Interform Computer Paper Limited | Wholesale & retail | 1987 |
| Interform Limited | Wholesale & retail | 2003 |
| Interim Logic Limited | Professional & scientific | 2003 |
| International Hospitality Recruitment Limited | Professional & scientific | 2008 |
| International IMS Limited | Education | 2025 |
| Intofinity Limited | Wholesale & retail | 2021 |
| Intraport Limited | Wholesale & retail | 1975 |
| Intrinzik Limited | Professional & scientific | 2014 |
| Intron Health Advisors Ltd | Professional & scientific | 2021 |
| Invergordon (H&I) Limited | Real estate | 2006 |
| Invest in India Limited | Real estate | 2020 |
| Invest in YOU Group Ltd | Information & communication | 2026 |
| Investa Homes CIC | Real estate | 2021 |
| Investments (UK) Ltd. | Real estate | 2014 |
| Ionimar Ltd | Construction | 2018 |
| Ionut Transfer Limited | Wholesale & retail | 2023 |
| Ipsychtec Group Limited | Financial services | 2018 |
| Ipsychtec IP Ltd | Administrative & support | 2019 |
| Ipsychtec Limited | Administrative & support | 2015 |
| IS Solutions and Services Ltd | Information & communication | 2023 |
| Ishiso Limited | Manufacturing | 2012 |
| Ismile Oral Care Limited | Health & social care | 2022 |
| Isometry Studio Ltd | Information & communication | 2025 |
| IT Agile Vision Ltd | Information & communication | 2022 |
| Italix Limited | Arts & recreation | 2012 |
| Itmarine Limited | Information & communication | 2001 |
| Itrack Solutions Ltd | Construction | 2007 |
| Itsanchana Ltd | Professional & scientific | 2025 |
| Ivory Oaks Ltd | Real estate | 2026 |
| Izzy's Consulting Services Ltd | Information & communication | 2019 |
| J & LK Consulting Ltd | Health & social care | 2013 |
| J & P Bianco Limited | Real estate | 2012 |
| J & R Consulting Ltd | Professional & scientific | 2012 |
| J & T Investments Limited | Real estate | 2005 |
| J (Associates) Limited | Professional & scientific | 2004 |
| J S D Products (UK) Limited | Wholesale & retail | 2007 |
| J-Uk Golf Limited | Administrative & support | 2014 |
| J.P.C. (Plant Hire & Haulage) Limited | Construction | 1987 |
| Jacek JCK Ltd | Wholesale & retail | 2022 |
| JAD Creative Ltd | Arts & recreation | 2025 |
| Jadas Capital Group Ltd | Real estate | 2025 |
| Jade Management Limited | Real estate | 2000 |
| Jadehill Properties Limited | Construction | 2000 |
| Jaderealm London Limited | Hospitality | 2018 |
| JAI Bhole Holdings Ltd | Real estate | 2026 |
| JAI Consultants Ltd | Real estate | 2014 |
| Jaid Property Limited | Information & communication | 2020 |
| James O'Donoghue Haulage Limited | Transport & logistics | 2019 |
| Jamiddletonproperty Limited | Real estate | 2025 |
| Jane Haynes Limited | Health & social care | 2000 |
| Janeiro Ltd | Wholesale & retail | 2026 |
| Janet E Davies Coaching and Consultancy Limited | Administrative & support | 2024 |
| Janet Manning Services Ltd | Health & social care | 2026 |
| Jannah & JO Ltd | Hospitality | 2024 |
| Jaqson Enterprises Ltd | Professional & scientific | 2024 |
| Jash Consultancy Services Limited | Professional & scientific | 2015 |
| Jasmine Akrami Ltd | Hospitality | 2025 |
| Jason Watts Limited | Information & communication | 2010 |
| JAY CEE Facilities Services Limited | Construction | 2005 |
| JAY Shah Enterprises Ltd | Information & communication | 2023 |
| Jaya Medical Practice Limited | Health & social care | 2016 |
| Jaybij Limited | Other services | 2021 |
| JBL Property Limited | Real estate | 2012 |
| Jcos Capital Limited | Financial services | 2013 |
| Jcos Partners Limited | Financial services | 2013 |
| Jcosta Property Solutions Ltd | Construction | 2026 |
| JCW Projects Limited | Construction | 2024 |
| Jelibi Ltd | Real estate | 2024 |
| Jemima Murphy Ltd | Arts & recreation | 2025 |
| Jennifer Rigby Consulting Limited | Professional & scientific | 2022 |
| JET Enterprises Limited | Manufacturing | 1987 |
| JET Imports Limited | Wholesale & retail | 2005 |
| JGH Building Services Limited | Construction | 2013 |
| Jhca Plastering & Rendering Limited | Construction | 2025 |
| Jilka Enterprises Ltd | Real estate | 2016 |
| Jill Anderson Limited | Administrative & support | 2007 |
| JIM JIM Services Ltd | Construction | 2023 |
| Jimmy Movement Lifestyle Ltd | Health & social care | 2019 |
| Jj’S Enrichment Program Limited | Health & social care | 2025 |
| JL Global Ltd | Professional & scientific | 2010 |
| JL Photography Limited | Professional & scientific | 2010 |
| JLD Consultants Limited | Professional & scientific | 2006 |
| JMA Group Limited | Administrative & support | 2017 |
| JMP Cosmetics Ltd | Health & social care | 2015 |
| JMP Partners Limited | Professional & scientific | 2025 |
| Joamis Ltd | Real estate | 2018 |
| JOE Trading Limited | Wholesale & retail | 2024 |
| Joel Montague Ltd | Arts & recreation | 2025 |
| Joffe Limited | Health & social care | 2012 |
| Johnson Properties Group Limited | Real estate | 2020 |
| Jointfind Residents Management Limited | Households | 1987 |
| Jopon Limited | Information & communication | 2017 |
| Jordan JP Plastering Ltd | Construction | 2024 |