| Ismaco Ltd | Health & social care | 2015 |
| Ismhl Ltd | Other services | 2024 |
| ISO Clarity Ltd | Professional & scientific | 2024 |
| ISO Compliance Limited | Professional & scientific | 2012 |
| ISO Sushi Sherwood Ltd | Hospitality | 2025 |
| Isobar Ltd | Professional & scientific | 2023 |
| Isors Property Ltd | Real estate | 2025 |
| Isos Cleaning and Removal Ltd | Administrative & support | 2025 |
| ISP Associates Limited | Professional & scientific | 2003 |
| Ispb 2006 Ltd | Professional & scientific | 2010 |
| Isquaredt Ltd | Professional & scientific | 2018 |
| ISS Labour Group Limited | Professional & scientific | 2013 |
| ISS PUB Co Ltd | Hospitality | 2018 |
| Istanbul Arnold Grill Ltd | Hospitality | 2025 |
| Istanbul Barber Nottingham Limited | Other services | 2021 |
| Istanbul Berber Limited | Other services | 2024 |
| Istanbul OFF Licence Ltd | Wholesale & retail | 2018 |
| Istanbul Turkish Barber Eastwood Ltd | Other services | 2025 |
| Isuna Financial Solutions Limited | Financial services | 2018 |
| ISW Electrical Ltd | Construction | 2018 |
| IT Analysis Solutions Ltd | Information & communication | 2015 |
| IT Brain Solutions Ltd | Information & communication | 2016 |
| IT Business Solutions Limited | Manufacturing | 2014 |
| IT Cyberservices Ltd | Information & communication | 2021 |
| IT Finnops Limited | Information & communication | 2025 |
| IT Kiosks (2022) Limited | Extraterritorial | 2012 |
| IT Solver Ltd | Information & communication | 2023 |
| IT Tech Solutions (UK) Ltd | Information & communication | 2015 |
| It's ALL About Padel Ltd | Arts & recreation | 2026 |
| It's Personal Gifts Limited | Manufacturing | 2021 |
| IT2 Limited | Information & communication | 1997 |
| IT24 UK Ltd | Information & communication | 2013 |
| IT2GO Limited | Information & communication | 2008 |
| Itac Tools UK Ltd | Wholesale & retail | 2025 |
| Italian Notts Ltd | Hospitality | 2026 |
| Italian Shop Limited | Wholesale & retail | 2016 |
| Italjet UK Ltd | Wholesale & retail | 2026 |
| Itchigoitchi Ltd | Agriculture & fishing | 2024 |
| Item Seven Restaurant Ltd | Hospitality | 2010 |
| Iterum Ltd | Professional & scientific | 2021 |
| Ites Enterprise Support Ltd | Information & communication | 2017 |
| Ithmaar Ltd | Professional & scientific | 2012 |
| ITS a Vibe Events Ltd | Hospitality | 2019 |
| ITS Blue Sky Ltd | Wholesale & retail | 2020 |
| ITS Care Ltd | Health & social care | 2024 |
| ITS Easy Limited | Wholesale & retail | 2026 |
| ITS Nott Just Food Opco Ltd | Hospitality | 2020 |
| Its-Intern Transport System (U.K.) Limited | Construction | 1982 |
| Itsjames Limited | Arts & recreation | 2022 |
| Itsmy Limited | Wholesale & retail | 2004 |
| Itwize Technology UK Limited | Information & communication | 2024 |
| It’S Luxe Living Ltd | Wholesale & retail | 2026 |
| It’S YOU and I Ltd | Education | 2025 |
| IUV Connect Ltd | Information & communication | 2024 |
| Ivan Johnson Limited | Construction | 2011 |
| Ivancath Ltd | Administrative & support | 2023 |
| Ivea Campervan Furniture Ltd | Manufacturing | 2024 |
| Ivelop Consulting Ltd | Information & communication | 2022 |
| Iversen Consulting Limited | Information & communication | 2025 |
| Ives & Co Solicitors Limited | Professional & scientific | 2012 |
| IVF Life UK Limited | Health & social care | 2011 |
| Ividus Ltd | Wholesale & retail | 2025 |
| Ivitamin Clinic Ltd | Real estate | 2021 |
| Ivix Collective Ltd | Wholesale & retail | 2022 |
| IVO Logistic Ltd | Transport & logistics | 2025 |
| Ivory Decorating Ltd | Construction | 2010 |
| Ivory EGG (UK) Limited | Wholesale & retail | 2005 |
| Ivory EGG Group Ltd | Professional & scientific | 2019 |
| Ivozone Clinic Ltd | Real estate | 2025 |
| IVY BLU Ltd | Administrative & support | 2016 |
| IVY Farm Kirklington Ltd | Real estate | 2019 |
| IVY House Weddings Limited | Other services | 2020 |
| IVY Leigh Homes Ltd | Real estate | 2024 |
| IVY Link Partnership Limited | Professional & scientific | 2012 |
| IVY Nails Limited | Other services | 2016 |
| IVY Plumbing Services Ltd | Construction | 2017 |
| IVY Properties Nottingham Limited | Real estate | 2020 |
| Ivynest Ltd | Other services | 2024 |
| Ivyplan Limited | Arts & recreation | 2005 |
| Ixia Plumbing & Heating Limited | Construction | 2009 |
| IXL Group Limited | Professional & scientific | 2024 |
| IYE Healthcare Limited | Health & social care | 2014 |
| Iyke & Vieon Limited | Real estate | 2019 |
| Iyke Limited | Manufacturing | 2023 |
| Iylas Limited | Wholesale & retail | 2024 |
| IZ Business Consultants Limited | Wholesale & retail | 2013 |
| Izabela Relocation Limited | Hospitality | 2020 |
| Izaynah Ltd | Professional & scientific | 2014 |
| Izel UK Limited | Wholesale & retail | 2024 |
| Izeon Ltd | Hospitality | 2025 |
| Izobilie Ltd | Information & communication | 2019 |
| Izyan Global Limited | Wholesale & retail | 2020 |
| Izzah Ltd | Education | 2025 |
| Izzco Limited | Financial services | 2018 |
| Izzie Cleaning Services Ltd | Administrative & support | 2025 |
| J & C Professionals Limited | Health & social care | 2011 |
| J & D Barbers Limited | Other services | 2011 |
| J & D Housing Limited | Real estate | 2017 |
| J & Dutt Holdings Limited | Real estate | 2023 |
| J & E Johnston (Developments) Ltd | Construction | 2017 |