| HSG Management Ltd | Real estate | 2022 |
| HTS Direct Limited | Manufacturing | 2002 |
| Huntaway Engineering Limited | Manufacturing | 2016 |
| HVH Trading Limited | Wholesale & retail | 2021 |
| Hyperlogic Limited | Professional & scientific | 2014 |
| I-Edu Ltd | Administrative & support | 2023 |
| Iancu Robert Ltd | Transport & logistics | 2019 |
| Ichor Management Limited | Financial services | 2023 |
| Ichor Midco Limited | Financial services | 2023 |
| Ichor Topco Limited | Financial services | 2023 |
| Icon Fasteners Limited | Extraterritorial | 1995 |
| Idlerocks Property Services Ltd | Construction | 2025 |
| Ieis Holdings Ltd | Financial services | 2020 |
| IG Stage Hire Ltd | Professional & scientific | 2015 |
| Impact China Limited | Wholesale & retail | 1996 |
| Impact Safety Netting Ltd | Manufacturing | 2013 |
| Imwc Ltd | Hospitality | 2025 |
| Incarnadine Limited | Real estate | 2011 |
| Inchi Oswestry Limited | Hospitality | 2023 |
| Inchi Properties Birmingham Limited | Hospitality | 2025 |
| Inchi Stone Limited | Hospitality | 2024 |
| Inclusive Insights Staffordshire Ltd | Education | 2025 |
| Inde Print Ltd | Manufacturing | 2021 |
| Indie Music Marketing Ltd | Professional & scientific | 2018 |
| Indie Music Matters CIC | Administrative & support | 2019 |
| Indu Suresh Limited | Health & social care | 2019 |
| Industrial Engineering & Installation Services - Ec&I Ltd | Manufacturing | 2022 |
| Industrial Engineering & Installation Services Limited | Construction | 2017 |
| Industrial Floor Treatments (Stone) Limited | Construction | 2004 |
| Industry Commercial Services Ltd | Professional & scientific | 2021 |
| Industry Creative Limited | Administrative & support | 2009 |
| Industry DJS Limited | Arts & recreation | 2012 |
| Infinite Life Sciences UK Ltd | Wholesale & retail | 2017 |
| Insite Hospitality Intelligence Ltd | Information & communication | 2020 |
| Inskip Roofing & Building Ltd | Construction | 2026 |
| Instem Clinical Holdings Limited | Information & communication | 2006 |
| Instem Clinical Limited | Information & communication | 2009 |
| Instem Life Science Systems Limited | Professional & scientific | 2001 |
| Instem Limited | Information & communication | 2010 |
| Instem LSS (North America) Limited | Information & communication | 1987 |
| Instem LSS Limited | Information & communication | 1998 |
| Instem Scientific Limited | Information & communication | 1999 |
| Instem Scientific Solutions Limited | Administrative & support | 1998 |
| Intercog Limited | Administrative & support | 2009 |
| IRS Investments Limited | Financial services | 2014 |
| Isobel Whittaker Funeral Services Ltd | Other services | 2021 |
| J Baines ICS Limited | Professional & scientific | 2021 |
| J Brown Developments Ltd | Real estate | 2021 |
| J Edwards Mobile Vehicle Repairs Ltd | Wholesale & retail | 2025 |
| J G Allbut & Company | Professional & scientific | 1982 |
| J M W Systems Limited | Manufacturing | 2000 |
| J.A. Bassett Limited | Real estate | 2019 |
| Jackson Electrical Services Staffs Ltd | Construction | 2024 |
| JAM4 Properties Ltd | Real estate | 2024 |
| Janat Telal Ltd | Health & social care | 2026 |
| Janet Reeve Limited | Professional & scientific | 2022 |
| Japanese Knotweed Expert Limited | Professional & scientific | 2014 |
| Jaton Limited | Extraterritorial | 1976 |
| Jayne Thorpe Education Limited | Education | 2024 |
| JCO Business Consultants Limited | Professional & scientific | 2022 |
| JCP Fixings Limited | Extraterritorial | 1989 |
| Jean Banner Ltd | Health & social care | 2025 |
| Jeannie-Us Perfumes Ltd | Wholesale & retail | 2020 |
| Jeff Bourne Properties Limited | Real estate | 2002 |
| Jeffries Property Holdings Limited | Financial services | 2013 |
| Jesse Shirley Consultancy Limited | Professional & scientific | 2012 |
| Jesse Shirley Minerals Limited | Other services | 2011 |
| Jhda Investments Limited | Professional & scientific | 2013 |
| Jhps Gardens Limited | Extraterritorial | 2018 |
| JJ Arts Limited | Education | 2025 |
| JJ Elton Limited | Agriculture & fishing | 2025 |
| JJ Garden Girl Ltd | Administrative & support | 2025 |
| JKA Estates Ltd | Real estate | 2022 |
| JM Absolute Ltd | Construction | 2019 |
| Jmrc Ltd | Information & communication | 2026 |
| JMW Media Ltd | Professional & scientific | 2018 |
| JMW Systems Group Ltd | Financial services | 2018 |
| John Burton Solicitors Limited | Professional & scientific | 2010 |
| Johnny'Sbuilding Ltd | Construction | 2022 |
| JON Hough - Technical Production Ltd | Administrative & support | 2026 |
| Jonny Utah Ltd | Financial services | 2025 |
| Joustra Creative Media Limited | Administrative & support | 2004 |
| Jrvl Limited | Administrative & support | 2022 |
| JRW Property and Maintenance Services Ltd | Construction | 2023 |
| JS Courier UK Limited | Transport & logistics | 2018 |
| JTW Motors Ltd | Wholesale & retail | 2022 |
| Jubilee Social Enterprises Limited | Hospitality | 2014 |
| Julia Mitchell Limited | Professional & scientific | 2011 |
| Just Wood Floors Ltd | Wholesale & retail | 2022 |
| Jwfocus Ltd. | Professional & scientific | 2019 |
| K - Line Building & Carpentry Services Limited | Construction | 2026 |
| K Hand Brand Vision Limited | Professional & scientific | 2007 |
| K J Green Services Ltd | Manufacturing | 2017 |
| K&B Spaces Ltd | Real estate | 2025 |
| K7 Limited | Administrative & support | 2014 |
| Kahana Technologies Limited | Information & communication | 2020 |
| Kakatiya Limited | Wholesale & retail | 2015 |
| Kctcsr Limited | Professional & scientific | 2025 |
| Kedron UK Limited | Administrative & support | 2003 |
| Keet Property Investments Ltd | Real estate | 2022 |