| Hydratech IP Ltd | Administrative & support | 2026 |
| Hydratech Marine Ltd | Manufacturing | 2026 |
| Hydroco Ltd | Professional & scientific | 2001 |
| HYL Jiankang Ltd | Other services | 2025 |
| Hypercloud Systems Ltd | Information & communication | 2023 |
| Hyperlane Logistics Ltd | Transport & logistics | 2026 |
| I'S SPOILT4CHOICE Ltd | Hospitality | 2023 |
| I-Glaze Limited | Construction | 2017 |
| I.V Clothing Ltd | Wholesale & retail | 2025 |
| IAN Swatton Limited | Information & communication | 2013 |
| Iclean and Clear Limited | Transport & logistics | 2013 |
| IL Foxo Ltd | Wholesale & retail | 2024 |
| IMLOGISTICS1302 Ltd | Transport & logistics | 2025 |
| Immopro Limited | Wholesale & retail | 2023 |
| Impact Design Ltd | Administrative & support | 2026 |
| Impact GAS Ltd | Construction | 2021 |
| Impulse Electrical Supplies Ltd | Wholesale & retail | 2014 |
| Impulse Holdings Limited | Financial services | 2017 |
| IN a JAM Ltd | Other services | 2022 |
| In-Sync Partners Ltd | Professional & scientific | 2020 |
| Inclusive Navigator Ltd | Information & communication | 2024 |
| Inkset Ltd | Professional & scientific | 2013 |
| Inkster Printing Ltd | Professional & scientific | 2024 |
| Inogroup Holdings Limited | Professional & scientific | 2002 |
| Inourarea CIC | Other services | 2023 |
| Inovad Limited | Manufacturing | 2012 |
| Inovolt Limited | Construction | 2000 |
| Inspired Media Productions Ltd | Information & communication | 2016 |
| Integer Consultancy Ltd | Professional & scientific | 2012 |
| International Urology Cancer Summit C.I.C. | Education | 2026 |
| Interwebsuperhighnet Ltd | Information & communication | 2023 |
| Investconstruct Ltd | Construction | 2016 |
| Invested Partnering Limited | Public administration | 2022 |
| Irea London Limited | Hospitality | 2024 |
| Ironframe Scaffolding Limited | Construction | 2026 |
| Isew Limited | Information & communication | 2006 |
| Island Sport and Leisure Limited | Arts & recreation | 1992 |
| Isle of Wight Sport Limited | Arts & recreation | 1984 |
| Istanbul Barbers Havant Ltd | Other services | 2026 |
| ITG Solutions Ltd | Information & communication | 2021 |
| Itsnewlife Limited | Wholesale & retail | 2023 |
| Ivan Homes Ltd | Real estate | 2023 |
| J & D Electrical Services Ltd | Construction | 2013 |
| J & E Vehicle Services Limited | Wholesale & retail | 2019 |
| J & H Beck Limited | Transport & logistics | 2025 |
| J & N Burrows (Havant) Limited | Other services | 1998 |
| J Calver Holdings Limited | Professional & scientific | 2005 |
| J Casey & Co Limited | Professional & scientific | 2006 |
| J M B Groundworks Ltd | Construction | 2023 |
| J&C Worley Limited | Information & communication | 2016 |
| J&F Group Ltd | Financial services | 2023 |
| J&G General Services Limited | Professional & scientific | 2014 |
| J&G Sunrise Properties Limited | Real estate | 2023 |
| J.F.H Electrical Contractors Ltd | Construction | 2019 |
| J.G.P Investment Properties Ltd | Real estate | 2019 |
| Jack James Ltd | Construction | 2019 |
| Jackson Productions Ltd | Arts & recreation | 2020 |
| Jacobs Joinery & Shop Fitting Holdings Limited | Financial services | 2017 |
| JAG Services UK Limited | Manufacturing | 2001 |
| Jagsnet Ltd | Wholesale & retail | 2021 |
| Jainsley Limited | Extraterritorial | 2020 |
| James Hutton Consulting Ltd | Administrative & support | 2026 |
| Janus Security Services Ltd | Other services | 2017 |
| Jarrah Venables Ltd | Other services | 2013 |
| Jason Ashman Ltd | Construction | 2016 |
| Jason Powers Consultants (UK) Limited | Professional & scientific | 2019 |
| Jassi Portsmouth Housing Limited | Real estate | 2018 |
| Jatawell UK Ltd | Wholesale & retail | 2022 |
| Jatcon Ltd | Professional & scientific | 2025 |
| Jays Transport (Havant) Limited | Transport & logistics | 2003 |
| Jc-Bars Ltd | Hospitality | 2025 |
| Jchary Consultancy Limited | Information & communication | 2024 |
| JD Technical Services Limited | Manufacturing | 2016 |
| JDW Groundworks Limited | Construction | 2022 |
| Jeffries Financial Services Ltd | Financial services | 2014 |
| Jessie JM Limited | Wholesale & retail | 2023 |
| JJD Electrical Ltd | Construction | 2021 |
| JKB Foods Ltd | Wholesale & retail | 2026 |
| JM Hampshire Property Ltd | Real estate | 2025 |
| JMC Meal Prep Limited | Hospitality | 2024 |
| JMD Fastfood Services Limited | Hospitality | 2017 |
| JN Railway Ltd | Construction | 2019 |
| Joanna Properties Ltd | Real estate | 2023 |
| JOE Hopkins Carpentry Limited | Manufacturing | 2025 |
| John Dwyer Bakery Limited | Manufacturing | 2003 |
| Johnson Accounting Solutions Limited | Professional & scientific | 2010 |
| Johnson Brickwork Limited | Construction | 2025 |
| JON Cole Limited | Professional & scientific | 2019 |
| Jonick Care Developments Limited | Construction | 2024 |
| Jord Composites Ltd | Manufacturing | 2024 |
| Journex Ltd | Transport & logistics | 2019 |
| JPR Construction S.E. Ltd | Construction | 2020 |
| JPR Investment Properties Ltd | Real estate | 2019 |
| Jtw.Constructionservices Ltd | Construction | 2025 |
| Justicehk Ltd | Real estate | 2021 |
| JW Roofing (Hampshire) Limited | Construction | 2021 |
| JWA Conseils Limited | Professional & scientific | 2018 |
| JWB Recruitment Ltd | Administrative & support | 2023 |
| JZ Enterprises Ltd | Wholesale & retail | 2022 |
| K & J Automotive Ltd | Wholesale & retail | 2018 |