| Hurstmoor Properties LLP | | 2015 |
| Hutchpeter Limited | Professional & scientific | 2008 |
| Hyland Financial Planning Ltd | Professional & scientific | 2018 |
| Hyperdive Ltd | Health & social care | 2019 |
| Hyperion Furniture Limited | Manufacturing | 2024 |
| Hystar Investments Limited | Real estate | 1989 |
| Hyundai Capital UK Limited | Financial services | 2012 |
| I & D Trans Limited | Transport & logistics | 2015 |
| I C Developments Surrey Ltd | Construction | 2021 |
| I D Devlin Limited | Professional & scientific | 2023 |
| I Formation Systems Limited | Real estate | 2016 |
| I Townsend Consultancy Ltd | Professional & scientific | 2019 |
| I-Stocktake Limited | Information & communication | 2017 |
| I. N. D. Limited | Administrative & support | 1996 |
| IAN Millward Forestry Limited | Agriculture & fishing | 1995 |
| IAN Tuttle Photography Ltd | Professional & scientific | 2016 |
| Ib-Crest Ltd | Administrative & support | 2026 |
| IBC Builders Ltd | Construction | 2017 |
| Idetect Events Ltd | Administrative & support | 2026 |
| Idékapital Investment Management Limited | Financial services | 2023 |
| Ifni Ltd | Professional & scientific | 2024 |
| IHA Solutions Ltd | Administrative & support | 2012 |
| IHM Associates Ltd | Professional & scientific | 2009 |
| IL Piave Limited | Administrative & support | 2006 |
| Illuminate Partners Ltd | Administrative & support | 2023 |
| Imaginativehr Ltd | Administrative & support | 2013 |
| Imcg Limited | Professional & scientific | 1994 |
| Imperial Oriental Ewell Ltd | Hospitality | 2025 |
| Imperial Plaice Ltd | Hospitality | 2016 |
| Imperium (Battle 2) Limited | Construction | 2021 |
| Imprint Education Ltd | Health & social care | 2025 |
| Improving Health in Business Limited | Professional & scientific | 2020 |
| IN the Marketplace (London) Limited | Real estate | 1980 |
| Indi POD Limited | Construction | 2020 |
| Indigo Yachting Limited | Administrative & support | 2019 |
| Indo Caribbean Limited | Hospitality | 2024 |
| Indulge Reigate Ltd | Hospitality | 2023 |
| Inexorable Ltd | Information & communication | 2025 |
| Infinity Creative Productions Ltd | Arts & recreation | 2025 |
| INFINN8 Limited | Other services | 2017 |
| Infors UK Limited | Professional & scientific | 1987 |
| Infx IP Ltd | Arts & recreation | 2010 |
| Ingenutix Ltd | Information & communication | 2017 |
| Ingham Consulting Limited | Information & communication | 2007 |
| Ingoodcompany Ltd | Professional & scientific | 2026 |
| Inhabit Group Ltd | Real estate | 2024 |
| Initiva Ltd | Wholesale & retail | 2026 |
| Inoumi Limited | Manufacturing | 2025 |
| Inside OUT Health (Reigate) Limited | Wholesale & retail | 2016 |
| Inspired Seasons Ltd | Wholesale & retail | 2005 |
| Intachem Holdings Limited | Financial services | 2009 |
| Integrity Consultations Limited | Health & social care | 2016 |
| Intelligent Healthcare Solutions Limited | Health & social care | 2006 |
| Intent Productions Ltd | Administrative & support | 2006 |
| Interalia Solutions Limited | Professional & scientific | 2011 |
| Interavia Limited | Professional & scientific | 2008 |
| Interbroadcast Limited | Professional & scientific | 1984 |
| Interim Financial Solutions Limited | Professional & scientific | 2006 |
| International Reach Consulting Ltd | Extraterritorial | 2025 |
| Intrinsic Animal Health Limited | Wholesale & retail | 2025 |
| Intrinsicomms Digital Ltd | Information & communication | 2026 |
| Intrum UK 2 Limited | Financial services | 1985 |
| Intrum UK Finance Limited | Administrative & support | 2001 |
| Intrum UK Group Limited | Financial services | 1998 |
| Intrum UK Holdings Limited | Financial services | 2001 |
| Intrum UK Limited | Administrative & support | 1999 |
| Ison Holdings Ltd | Real estate | 2025 |
| ISP Theory Ltd | Manufacturing | 2025 |
| Itssarahgordon Limited | Professional & scientific | 2023 |
| Ives & Watson Ltd | Other services | 2023 |
| Ivydeal Investments Limited | Real estate | 1997 |
| J & J Incorporated Ltd | Information & communication | 2010 |
| J D Construction & Management Services Limited | Construction | 2003 |
| J G Landscaping Group Limited | Administrative & support | 2023 |
| J L R Building & Maintenance Services Ltd | Construction | 2014 |
| J M Marketing Events Limited | Administrative & support | 2000 |
| J Wiggins Limited | Administrative & support | 2005 |
| J&S Fuel Ltd | Wholesale & retail | 2017 |
| J&S Supreme Ltd | Professional & scientific | 2022 |
| J. Grant Holdings PLC | | 1986 |
| J.Bader(Cleaners)Limited | Hospitality | 1960 |
| J.M.Wood Limited | Wholesale & retail | 1959 |
| J.P. (Sussex) Limited | Wholesale & retail | 1998 |
| J.W. Resourcing Limited | Professional & scientific | 2008 |
| J2 Physiocare Ltd | Health & social care | 2022 |
| Jackanory PUB Limited | Hospitality | 2025 |
| Jackcompany Limited | Construction | 2025 |
| Jackson CAM Limited | Information & communication | 2016 |
| Jackson Landscaping Services Limited | Administrative & support | 2021 |
| Jade Recruitment Limited | Administrative & support | 2008 |
| Jalog Consultants Ltd | Professional & scientific | 2019 |
| Jamco Consulting Ltd | Professional & scientific | 2017 |
| James Ball Consulting Limited | Information & communication | 2018 |
| James Conway Landscaping Ltd | Administrative & support | 2026 |
| Jamesdean (Redhill) Limited | Real estate | 2006 |
| Jamfootball Limited | Education | 2026 |
| Jamie Lawrence Football Academy Limited | Arts & recreation | 2025 |
| Jane Bowden Architects Limited | Professional & scientific | 2013 |
| Janire Business Solutions Ltd | Administrative & support | 2010 |
| Janire Mortgages Ltd | Financial services | 2025 |