| Ironsky Housing Ltd | Hospitality | 2024 |
| Irontec Limited | Manufacturing | 2019 |
| Irregular Media Ltd | Professional & scientific | 2025 |
| Irrigation Services Plus L.P. | | 2008 |
| Irsa Limited | Real estate | 2021 |
| Irshad Brothers Properties Ltd | Hospitality | 2024 |
| Irton Trade LP | | 2015 |
| IRV Contracts L.P. | | 2012 |
| Irvin Alliance LP | | 2012 |
| Irvine Trading LP | | 2012 |
| Irving Holdings (Scotland) Limited | Administrative & support | 2024 |
| Irwin's Tea Limited | Wholesale & retail | 2023 |
| Irzam Limited Limited | Wholesale & retail | 2023 |
| IS Actuary Ltd | Information & communication | 2026 |
| IS Integrated Systems L.P. | | 2009 |
| IS8 Investments Limited | Financial services | 2025 |
| IS8 Ltd | Real estate | 2024 |
| Isabel Living Limited | Wholesale & retail | 2021 |
| Isabell Mehl Ltd | Arts & recreation | 2023 |
| Isabelle Consulting Co. Limited | Professional & scientific | 2024 |
| Isaca Scotland Chapter Limited | Other services | 2018 |
| Isapi LP | | 2003 |
| ISB Global Group LP | | 2021 |
| ISC Civils (Scotland) Limited | Construction | 2018 |
| ISE OWO CIC | Education | 2025 |
| Isel Solutions Limited | Professional & scientific | 2025 |
| Isernia LP | | 2012 |
| Iseton Maintenance Services Ltd | Construction | 2012 |
| ISG Alliance LP | | 2015 |
| Ishavi Estates Limited | Real estate | 2018 |
| Ishbel Benzie Ltd | Health & social care | 2025 |
| Ishi (Hanover) Limited | Other services | 2013 |
| Ishi (Marchmont) Limited | Other services | 2008 |
| Ishi Southside Ltd | Other services | 2023 |
| Ishi Style Ltd | Other services | 2023 |
| Ishi Trading Ltd | Hospitality | 2025 |
| Ishiku Wagyu Ltd | Hospitality | 2025 |
| Ishmaari Prop Limited | Real estate | 2018 |
| Ishtarzith Ltd | Administrative & support | 2023 |
| Isis III Carry LP | | 2002 |
| Iskcon Limited | Administrative & support | 2019 |
| Iskocya Fenerbahceliler Dernegi CIC | Other services | 2025 |
| Isla Azul SP | | 2001 |
| Isla Capital Development | | 1991 |
| Isla Margarita SP | | 2003 |
| Isla Mines Limited | Real estate | 1969 |
| Isla Morada SP | | 2001 |
| Isla Rose Piano Ltd | Education | 2015 |
| Isla Trading Limited | Wholesale & retail | 2018 |
| Isla&Co. Travel Ltd | Administrative & support | 2025 |
| Islam & Uddin Properties Ltd | Real estate | 2026 |
| Islamic Treasure Ltd | Wholesale & retail | 2023 |
| Island Adventures Productions Ltd | Information & communication | 2026 |
| Island Group Ltd | Information & communication | 2006 |
| Island Heights LP | | 2003 |
| Island Life Productions CIC | Administrative & support | 2019 |
| Island Title (AB) Limited | Professional & scientific | 1998 |
| Island Title Limited | Professional & scientific | 1993 |
| Islander Edinburgh Ltd | Wholesale & retail | 2022 |
| Islander Group Ltd | Wholesale & retail | 2024 |
| Islandhill Limited | Wholesale & retail | 2025 |
| Islar Property Ltd | Real estate | 2020 |
| Isle DM Limited | Administrative & support | 2020 |
| Isle of HJP Limited | Financial services | 2026 |
| Isle of Scalpay Limited | Other services | 2020 |
| Isle of Style Ltd | Wholesale & retail | 2024 |
| Isles Partners | | 2000 |
| Isleview Limited | Professional & scientific | 1997 |
| Islyn Spirits Limited | Wholesale & retail | 2026 |
| ISM Investments Limited | Real estate | 2023 |
| ISM Travels Limited | Information & communication | 2025 |
| Ismir Investments LP | | 2002 |
| Isms Holding LP | | 2025 |
| Isna Limited | Administrative & support | 2023 |
| ISO Assured Ltd | Professional & scientific | 2010 |
| Isol Trading LP | | 2015 |
| Isola Edinburgh Limited | Hospitality | 2017 |
| ISOLAR76 Ltd | Information & communication | 2025 |
| Isoline Sales L.P. | | 2010 |
| Isomer Capital GP2 LLP | | 2026 |
| Isomer Capital IV GP Limited | Financial services | 2026 |
| Isomer Capital IV LP | | 2026 |
| Isoplan Ltd | Financial services | 2000 |
| Isoplan UK Ltd | Professional & scientific | 1990 |
| Isori Limited | Hospitality | 2024 |
| ISP International LP | | 2016 |
| ISP Portobello Ltd | Other services | 2022 |
| ISQUARE19 Limited | Wholesale & retail | 2025 |
| Israel Haifa Ounuote International Chemical Co., Ltd. | Extraterritorial | 2020 |
| Isrutech Limited | Professional & scientific | 2022 |
| Isso Construction Ltd | Construction | 2024 |
| IST3 Manesse PE L.P. | | 2016 |
| IST3 Manesse PE2 L.P. | | 2019 |
| Istalla International Finance & Co. | | 1992 |
| Istanbul 2 Limited | Wholesale & retail | 2023 |
| Istanbul BARBER1 Ltd | Other services | 2025 |
| Istar Business LP | | 2014 |
| Isternia Trading Ltd | Hospitality | 2026 |
| Istomedia Limited | Information & communication | 2015 |
| Iszc Property Ltd | Real estate | 2026 |