| Hudson Weasley Ltd | Real estate | 2017 |
| Huets Carpentry & Building Ltd | Construction | 2025 |
| Hugo Morris Limited | Wholesale & retail | 2007 |
| Hulanicki Archive Limited | Professional & scientific | 2024 |
| Huluki Property Group Limited | Hospitality | 2016 |
| HUM Consultancy Ltd | Administrative & support | 2016 |
| Human Integration Limited | Professional & scientific | 2013 |
| Human Ltd | Information & communication | 2026 |
| Humanity Research Consultancy Limited | Professional & scientific | 2019 |
| Hunciecroft Solar Limited | Energy | 2014 |
| Hundredbears Limited | Administrative & support | 2017 |
| Hunger Hill Solar Project Limited | Energy | 2014 |
| Hungry Minds After School Club Limited | Education | 2021 |
| Hungry Minds Childcare Limited | Education | 2011 |
| Hunter and Black Ltd | Real estate | 2024 |
| Hunterwell Recruitment Ltd | Administrative & support | 2021 |
| Hurcott Solar Limited | Energy | 2014 |
| Hurley Heating and Plumbing Limited | Construction | 2025 |
| Hurley Heating Limited | Construction | 2013 |
| Hurley Invest Limited | Other services | 2023 |
| Hurlyburly Theatre | Arts & recreation | 2020 |
| Hurren & Glynn Carpets and Flooring Limited | Wholesale & retail | 2009 |
| Hursley Road Dental Practice Limited | Health & social care | 2021 |
| Hurst Property Ltd | Construction | 2018 |
| Hurstwood Equity Limited | Households | 1955 |
| Hussein Optical Limited | Health & social care | 2020 |
| Hustle & HER Ltd | Professional & scientific | 2026 |
| Hutchings Media Limited | Professional & scientific | 2012 |
| Hutchins Guitars Ltd | Wholesale & retail | 2009 |
| Huxley & Huxley Ltd | Education | 2025 |
| Huzzah Communications Ltd | Hospitality | 2022 |
| HW Income & Growth Ltd | Financial services | 2016 |
| Hwange Properties Limited | Real estate | 2009 |
| Hydra Support Limited | Manufacturing | 2014 |
| Hylands House Care Ltd | Health & social care | 2012 |
| Hyperset Group Ltd | Administrative & support | 2024 |
| Hypnosis for Wellbeing Ltd | Other services | 2022 |
| Hypo Warehouses Limited | | 1972 |
| Hythechoice Limited | Households | 1975 |
| I & O Commercial Flooring Ltd | Construction | 2023 |
| I Financial Solutions Limited | Financial services | 2010 |
| I Gigi General Store Limited | Wholesale & retail | 2004 |
| I Paint Decorating Ltd | Construction | 2017 |
| I Work in Europe Limited | Extraterritorial | 2014 |
| I'M Doing Fine Ltd | Arts & recreation | 2019 |
| I-Qi-Coaching Ltd | Other services | 2021 |
| I-Tech Links Brighton Ltd | Wholesale & retail | 2014 |
| I.I.J Logistics Limited | Administrative & support | 2025 |
| I.M.R. Executive Limited | Administrative & support | 2006 |
| I.O.W. Contractors Ltd | Administrative & support | 2012 |
| I.P.I. Limited | Real estate | 1981 |
| IAN White Productions Ltd | Information & communication | 2011 |
| IB Design Studio Ltd | Real estate | 2026 |
| IBD Relief Ltd | Health & social care | 2015 |
| Ibex Systems (Sussex) Limited | Information & communication | 2003 |
| Ibex [Southern] Limited | Information & communication | 2002 |
| IBH Executive Ltd | Administrative & support | 2010 |
| Ibkamarastudios Limited | Arts & recreation | 2018 |
| Icarus Outdoors Ltd | Administrative & support | 2023 |
| Ice Cafe Limited | Hospitality | 2011 |
| Ice Liquor Ltd | Wholesale & retail | 2026 |
| Iclinic Pro Limited | Information & communication | 2019 |
| Icollect.It Ltd | Information & communication | 2022 |
| Icon Botanics Ltd | Manufacturing | 2020 |
| Icore Media Limited | Administrative & support | 2011 |
| Icore Security and Solar Services Limited | Information & communication | 2021 |
| ICP Search Limited | Professional & scientific | 2006 |
| ID8 Design and Build Ltd | Extraterritorial | 2016 |
| IDA Sports Ltd | Wholesale & retail | 2021 |
| Idea Steer Limited | Information & communication | 2015 |
| Ideas Library Ltd | Professional & scientific | 2006 |
| Idhika RAJ FX Limited | Financial services | 2026 |
| Idiom Consulting Ltd | Information & communication | 2013 |
| Idji Store Limited | Wholesale & retail | 2021 |
| IDK Software Limited | Extraterritorial | 1997 |
| Idolla-Del Ltd | Construction | 2025 |
| Iexcel Ltd | Professional & scientific | 2019 |
| Ifbb.Uk | Arts & recreation | 2026 |
| Ifnotmeifnotnow Ltd | Education | 2021 |
| Iformation Limited | Professional & scientific | 2019 |
| Ignition Partners Valencia Ltd | Administrative & support | 2026 |
| II Holding Limited | Information & communication | 2017 |
| IINSURE365 Limited | Financial services | 1996 |
| Ikonoklast Ltd | Information & communication | 2013 |
| Ilkley Court Freeholders Limited | Households | 2000 |
| Illustrious Wizards Limited | Professional & scientific | 2023 |
| Illyria Reserve Ltd | Wholesale & retail | 2026 |
| Ilovelucie Limited | Wholesale & retail | 2007 |
| Imaginationade Limited | Arts & recreation | 2024 |
| Imber Enterprises Limited | Professional & scientific | 2011 |
| Imber Holdings Ltd | Financial services | 2023 |
| Imblakeconsulting Limited | Professional & scientific | 2015 |
| Imereo Limited | Professional & scientific | 2017 |
| Imex America Limited | Administrative & support | 2010 |
| IMI LOA Limited | Wholesale & retail | 2017 |
| Iminore Limited | Information & communication | 1997 |
| Impace Limited | Professional & scientific | 2021 |
| Impact Decor Ltd | Construction | 2025 |
| Impact Screen Solutions Limited | Wholesale & retail | 2008 |
| Imperial Care Group 2 Ltd | Financial services | 2021 |