| Howard John Stephens Ltd | Information & communication | 2012 |
| However YOU Like to Break Limited | Education | 2020 |
| HP Accomplish Ltd | Education | 2026 |
| HR Consultancy by HER Ltd | Administrative & support | 2026 |
| Huben Travel Limited | Administrative & support | 2020 |
| Huben Travel Logistics and Events Limited | Administrative & support | 2023 |
| Huddle MEP Limited | Professional & scientific | 2026 |
| Humphrey'Stech Limited | Professional & scientific | 2025 |
| Hussain MED Ltd | Health & social care | 2015 |
| Hutson Jones Accounting Limited | Professional & scientific | 2018 |
| HW Capital Builders Limited | Construction | 2025 |
| Hyde Business Consulting Limited | Professional & scientific | 2020 |
| I Calabresi Ltd. | Hospitality | 2011 |
| I&R Investment Group Ltd | Real estate | 2025 |
| IAN Wells and Associates Ltd | Construction | 2012 |
| IFA Trading Ltd | Hospitality | 2012 |
| Ifalore Securities Limited | Information & communication | 2007 |
| IGD Building Services Limited | Construction | 2015 |
| Iico Limited | Real estate | 2025 |
| Iksir Ltd | Wholesale & retail | 2023 |
| IMA Media Limited | Information & communication | 2014 |
| Imaginfinity Ltd | Real estate | 2025 |
| IN House Casting Ltd | Arts & recreation | 2009 |
| IN Tandem Training Ltd | Professional & scientific | 2024 |
| Inca Data Services Limited | Information & communication | 1996 |
| Increase Rental Sales Ltd | Administrative & support | 2021 |
| Indm Limited | Wholesale & retail | 2023 |
| Industrial Vacuums Direct Ltd | Administrative & support | 2021 |
| Ineedaelectrician.Com Limited | Manufacturing | 2016 |
| Inflataseal Ltd | Wholesale & retail | 2025 |
| Info Aspect Ltd. | Information & communication | 2012 |
| Ingenious Logic Limited | Information & communication | 2014 |
| INK 10 Security Services Ltd | Administrative & support | 2019 |
| Innerspring Counselling Ltd | Other services | 2021 |
| INNOV8 Property Ltd | Construction | 2020 |
| INP Housing Limited | Real estate | 2023 |
| Insight MEP Management Ltd | Professional & scientific | 2018 |
| Insitus IT Limited | Information & communication | 2016 |
| Inspired Hair Supplies Limited | Wholesale & retail | 2012 |
| Instant Property Holdings Ltd | Real estate | 2022 |
| Interheat Limited | Professional & scientific | 2012 |
| Interior Fitout Solutions Ltd | Construction | 2020 |
| Interno Design Ltd | Professional & scientific | 2020 |
| Interport Limited | Wholesale & retail | 1981 |
| Into the Build Ltd | Information & communication | 2026 |
| Investao Limited | Financial services | 2018 |
| Investao Operations Limited | Financial services | 2019 |
| Invia Group Limited | Construction | 2020 |
| IO Digitech Limited | Information & communication | 2023 |
| Ironman Developments Ltd | Manufacturing | 2018 |
| Ishka Consulting Limited | Professional & scientific | 2023 |
| IT Transformation Solutions Limited | Information & communication | 2012 |
| Itsecure Limited | Information & communication | 2018 |
| Ivalley Properties Limited | Real estate | 2021 |
| Ivan Leon Consulting Services Ltd | Information & communication | 2014 |
| I’Ll Take the Window Seat Limited | Administrative & support | 2025 |
| J C Gould Limited | Real estate | 2024 |
| J Ewin Windows Ltd | Construction | 2025 |
| J Group Property Limited | Real estate | 2022 |
| J H Lorimer Limited | Wholesale & retail | 1949 |
| J H Sonographer Ltd | Health & social care | 2025 |
| J K Safety Ltd | Public administration | 2012 |
| J Watson Services Ltd | Other services | 2021 |
| J&H Recovery Ltd | Wholesale & retail | 2018 |
| J&I Global Solutions Ltd | Professional & scientific | 2025 |
| J&R Spencer Ltd | Hospitality | 2023 |
| J-Tech Systems Limited | Construction | 2010 |
| J. & B. Newspapers | Real estate | 1961 |
| J. Golding & Sons (1960) | Real estate | 1960 |
| J. J. Callaghan Property Maintenance Limited | Construction | 2013 |
| J.C Building and Construction Limited | Construction | 2024 |
| J/Fly Publishing Limited | Information & communication | 1997 |
| Jacelet Property Ltd | Real estate | 2023 |
| Jack Golding & Sons | Construction | 1959 |
| Jaco & Sons Limited | Wholesale & retail | 2026 |
| Jade Homes Ltd | Real estate | 2022 |
| Jagdish Ltd | Wholesale & retail | 2023 |
| James Nicholson Property Investing Ltd | Real estate | 2023 |
| Jamtix Ltd | Administrative & support | 2011 |
| Jati Limited | Wholesale & retail | 2002 |
| Jati Properties LLP | | 2009 |
| Jaybax Limited | Professional & scientific | 2018 |
| Jays Cash & Carry Glass Ltd | Extraterritorial | 2014 |
| JB4 Dating (Just Before Dating) Limited | Manufacturing | 2025 |
| Jbfe Traders Ltd | Wholesale & retail | 2023 |
| JCA School Support Limited | Professional & scientific | 2011 |
| JCK Business Solutions Limited | Professional & scientific | 2024 |
| Jcpayne Solutions Ltd | Transport & logistics | 2026 |
| JD Analytics Ltd | Professional & scientific | 2024 |
| JD Electrical Surrey Ltd | Construction | 2022 |
| Jdatfx Limited | Education | 2025 |
| Jdchospitality Ltd | Hospitality | 2022 |
| Jeffries Commissioning Ltd | Professional & scientific | 2018 |
| JH Maintenance Ltd | Construction | 2008 |
| Jigsaw Builds Ltd | Construction | 2026 |
| JJ Antiques Ltd | Wholesale & retail | 2021 |
| JJ Movers Ltd | Transport & logistics | 2018 |
| JJH Rigging Ltd | Construction | 2021 |
| JK Group (UK) Limited | Wholesale & retail | 2004 |
| JK Group Wholesale Ltd | Wholesale & retail | 2021 |