| Infra Power Projects Limited | Construction | 2026 |
| Infraglo (Sheffield) Limited | Manufacturing | 1990 |
| Inframe Gallery Ltd | Other services | 2009 |
| Infusion Construction & Property Ltd | Construction | 2026 |
| Inga Private Ltd | Hospitality | 2026 |
| Ingle Lifestyle Coaching Limited | Health & social care | 2024 |
| Ingleford Stays Ltd | Hospitality | 2026 |
| Inglegym Limited | Arts & recreation | 2017 |
| Ingram Leisure Ltd | Hospitality | 2025 |
| Ingrid Estates Ltd | Real estate | 2025 |
| Ingvar Interactive Ltd | Information & communication | 2026 |
| Inifinity Home Solutions Ltd | Construction | 2014 |
| Inifinity Homes Ltd | Construction | 2022 |
| Inikoo Ltd | Information & communication | 2011 |
| Inimba Ltd | Professional & scientific | 2021 |
| Initial Education Limited | Education | 2016 |
| INITIATIVE4HEALTHYLIVING Ltd | Administrative & support | 2023 |
| INITIUM24 Ltd | Other services | 2024 |
| Inixio Limited | Professional & scientific | 2020 |
| INK & Water Coffee Ltd | Professional & scientific | 2013 |
| INK & Water Ltd | Professional & scientific | 2011 |
| INK of Coco Skincare Ltd | Manufacturing | 2019 |
| INK Spot Tattoo & Piercing Ltd | Arts & recreation | 2025 |
| Inkerton Limited | Arts & recreation | 2013 |
| Inkglorious Tattoo Ltd | Other services | 2026 |
| Inkplast Limited | Construction | 2017 |
| Inkredible Kidz Solutions Ltd | Education | 2025 |
| Inkredible Tattoo Limited | Wholesale & retail | 2014 |
| Inky Board Limited | Professional & scientific | 2016 |
| Inmars Business Group Ltd | Transport & logistics | 2021 |
| Inn at the Electra Ltd | Hospitality | 2024 |
| Inn Xxiii Ltd | Hospitality | 2024 |
| INN2PLACE Limited | Hospitality | 2025 |
| Innaterra Ltd | Professional & scientific | 2016 |
| Innaxsys Ltd | Information & communication | 2012 |
| Innception Limited | Hospitality | 2012 |
| Innception Properties Ltd | Real estate | 2015 |
| Innercityhealers CIC | Health & social care | 2025 |
| Innhouse Drinks Ltd | Wholesale & retail | 2020 |
| Innocenza Lifestyle Ltd | Wholesale & retail | 2006 |
| Innorail UK Ltd | Transport & logistics | 2018 |
| Innotek Consulting Limited | Professional & scientific | 2018 |
| Innotoyia Co., Ltd | Wholesale & retail | 2025 |
| Innovare Investments Group Limited | Financial services | 2024 |
| Innovate Mouldings Ltd | Manufacturing | 2021 |
| Innovateworks Inc Ltd | Information & communication | 2023 |
| Innovation AEP CIC | Education | 2026 |
| Innovation Alloys Limited | Wholesale & retail | 2010 |
| Innovation Electrical & Fire Ltd | Extraterritorial | 2021 |
| Innovation Fire & Data Ltd | Extraterritorial | 2021 |
| Innovation Renovations Ltd | Construction | 2021 |
| Innovation Security & Wifi Ltd | Construction | 2018 |
| Innovation VAC Alloys Ltd | Wholesale & retail | 2022 |
| Innovations (U.K.) Ltd | Administrative & support | 2020 |
| Innovativ Ltd | Construction | 2011 |
| Innovativ Properties Limited | Real estate | 2017 |
| Innovative Construction Materials and Placing Method Ltd | Construction | 2023 |
| Innovative Education AP Limited | Education | 2025 |
| Innovative Global Services Limited | Wholesale & retail | 2012 |
| Innovative Infotech Ltd | Information & communication | 2024 |
| Innovative Media Agency Ltd | Arts & recreation | 2019 |
| Innovative Properties and Homes Ltd | Households | 2026 |
| Innovative Ventures Limited | Information & communication | 2024 |
| Innovativus Ltd | Other services | 2023 |
| Innovbuild Ltd | Professional & scientific | 2024 |
| Innovity Limited | Professional & scientific | 2023 |
| Innsun Morpeth Limited | Hospitality | 2025 |
| Inova Consultancy Limited | Professional & scientific | 2004 |
| Inova Multi-Academy Trust Limited | Education | 2011 |
| Inovink Limited | Professional & scientific | 2004 |
| Inpo Service Ltd | Administrative & support | 2025 |
| Inqira Ltd | Information & communication | 2023 |
| Inseam Ltd | Wholesale & retail | 2024 |
| Inside and Outside Limited | Construction | 2025 |
| Inside Edge Construction Ltd | Construction | 2019 |
| Inside Edge Mortgages Ltd | Financial services | 2023 |
| Inside Food Limited | Hospitality | 2018 |
| Inside Foodservice Limited | Hospitality | 2008 |
| Inside OUT Schools Limited | Education | 2011 |
| Insideout Property Solutions Ltd | Construction | 2020 |
| Insight Development Corporation Limited | Information & communication | 2000 |
| Insight Direct (GB) Limited | Information & communication | 1998 |
| Insight Direct (Services) Limited | Information & communication | 1998 |
| Insight Direct (UK) Ltd | Information & communication | 1991 |
| Insight Enterprises UK Limited | Information & communication | 2000 |
| Insight Finance Solutions Ltd | Professional & scientific | 2019 |
| Insight Imaging Ltd. | Information & communication | 2015 |
| Insight Management and Systems Consultants Limited | Professional & scientific | 1991 |
| Insight Networking Solutions Limited | Information & communication | 2002 |
| Insight New Media Productions Ltd | Information & communication | 2008 |
| Insight UK Acquisitions Limited | Information & communication | 2001 |
| Insighted Ltd | Education | 2024 |
| Insightful Strategies & Solutions Ltd | Professional & scientific | 2024 |
| Insistboard Limited | Professional & scientific | 1897 |
| Insomniac Touring Ltd | Transport & logistics | 2024 |
| Inspaceconstruction Limited | Construction | 2021 |
| Inspec Solutions Ltd | Information & communication | 1999 |
| Inspect & Protect Limited | Extraterritorial | 2006 |
| Inspectus Ltd | Financial services | 2024 |
| Inspirations Sheffield Limited | Health & social care | 2022 |