| Independent Training Services Limited | Education | 2001 |
| Independent Trucker Ltd | Transport & logistics | 2022 |
| Indian Food Hawker Ltd | Hospitality | 2018 |
| Indoor Cricket and Golf Centres Ltd | Arts & recreation | 2023 |
| Indulgence Cafe Cakes & Shakes Ltd | Hospitality | 2026 |
| Industrial Door Solutions Limited | Construction | 2003 |
| Industrial Wheels and Castors Limited | Professional & scientific | 2006 |
| Inertia Creative Limited | Information & communication | 2022 |
| Infinite Fire & Security Limited | Administrative & support | 2011 |
| Infinite Growth Collective Ltd | Wholesale & retail | 2025 |
| Infinite Pro Electrical Ltd | Wholesale & retail | 2012 |
| Infiniti Scaffolding and Access Limited | Extraterritorial | 2024 |
| Infinitus 22 Limited | Real estate | 2025 |
| Infinitus Delta (Partners) Limited | Real estate | 2023 |
| Infinitus Delta (Sales & Letting) Limited | Real estate | 2025 |
| Infinitus Delta Limited | Real estate | 2020 |
| Infinity Sports Massage Ltd | Other services | 2022 |
| Infinity TEK Ltd | Wholesale & retail | 2025 |
| Inflatica Ltd | Administrative & support | 2026 |
| Inform Precision Engineering Limited | Manufacturing | 1991 |
| Informate UK Ltd | Information & communication | 2007 |
| Initial Plant Training Ltd | Education | 2019 |
| INK Junkies Barnsley Ltd | Other services | 2026 |
| Inkberry Creative Limited | Information & communication | 2013 |
| Inline Brickwork Ltd | Construction | 2010 |
| Inn @ Top-A-Dog-Lane Ltd | Hospitality | 2019 |
| Innova Electrical Services Ltd | Construction | 2010 |
| Innovate Homes Limited | Real estate | 2025 |
| Innovate Interiors Ltd | Construction | 2020 |
| Innovate PR Management Ltd | Professional & scientific | 2019 |
| Innovate Property Services Ltd | Real estate | 2022 |
| Innovation Productions Limited | Wholesale & retail | 2000 |
| Innovations Wakefield Limited | Health & social care | 2024 |
| Innovative Scaffold Designs Ltd | Construction | 2023 |
| Innovative Support Systems Ltd. | Professional & scientific | 2010 |
| Innovolt Limited | Construction | 2023 |
| Inox Passivation Ltd | Manufacturing | 2019 |
| Inscape Construction Ltd | Construction | 2023 |
| Inscape Properties Limited | Real estate | 2022 |
| Inside Leadership Ltd | Education | 2015 |
| Inspire Development Academy Ltd | Education | 2023 |
| Inspire Everyone CIC | Arts & recreation | 2025 |
| Inspire U Pain Sciences Limited | Professional & scientific | 2026 |
| Instabox Ltd | Hospitality | 2020 |
| Instadia Education Limited | Education | 2024 |
| Instamotive Ltd | Wholesale & retail | 2019 |
| Institute for Small Business and Entrepreneurship | Other services | 1991 |
| Insulation Logistics Ltd | Manufacturing | 2024 |
| Insusmart Ltd | Construction | 2025 |
| Intake Developments Limited | Wholesale & retail | 1971 |
| Integer Logistics Limited | Transport & logistics | 2018 |
| Integral Network Solutions Limited | Information & communication | 2007 |
| Integrative Health Education Ltd | Health & social care | 2014 |
| Integrid Ltd | Professional & scientific | 2022 |
| Integritam Limited | Professional & scientific | 2018 |
| Integrity Fire and Security Limited | Administrative & support | 2012 |
| Intelixa Limited | Information & communication | 2026 |
| Intelligent Building Services (Maintenance) Limited | Construction | 1995 |
| Intelligent Machines Limited | Professional & scientific | 2014 |
| Interface Vehicle Services Limited | Wholesale & retail | 2009 |
| International Bathrooms Limited | Wholesale & retail | 2023 |
| International Destination Management Consultancy Limited | Administrative & support | 2012 |
| Internet Accounting Corporation Limited | Professional & scientific | 2020 |
| Internet Marketing Platinum Limited | Information & communication | 2009 |
| Intolernate Ltd | Health & social care | 2026 |
| Intrigue at Deighton Management Limited | Professional & scientific | 2007 |
| Invadex Chiltern Limited | Wholesale & retail | 2009 |
| Investiverse Limited | Financial services | 2023 |
| Investiverse Property Limited | Real estate | 2023 |
| Invetiq Limited | Information & communication | 2012 |
| Invicta Joinery & Timber Frame Limited | Construction | 2017 |
| Invictus Aviation Ltd | Professional & scientific | 2016 |
| Invisible Flock Co | Arts & recreation | 2014 |
| Invoke Consultancy Ltd | Professional & scientific | 2012 |
| Inweregbu Limited | Health & social care | 2019 |
| Ionut Delivery Ltd | Transport & logistics | 2017 |
| Iphm Limited | Hospitality | 2014 |
| IQS Partners Limited | Professional & scientific | 2014 |
| Irent Properties (Yorkshire) Ltd | Real estate | 2023 |
| Iridium Homes Limited | Real estate | 2020 |
| Irmauk Limited | Financial services | 2026 |
| Irmauk Property Ltd | Real estate | 2026 |
| Iron Paradise Limited | Arts & recreation | 2019 |
| Iron-Man Fabs Limited | Construction | 2025 |
| Ironstone Services Ltd | Financial services | 2017 |
| IS Powder Coating Ltd | Professional & scientific | 2024 |
| Issoir Ltd | Wholesale & retail | 2021 |
| ISTANBUL34 Ltd | Hospitality | 2025 |
| Isteel Fabrications Ltd | Manufacturing | 2020 |
| IT Moon Ltd | Information & communication | 2020 |
| Itacons Consulting Ltd | Professional & scientific | 2023 |
| Itds Solutions Limited | Information & communication | 2013 |
| Itechnology Business Solutions Limited | Information & communication | 2012 |
| Itnplus Ltd | Manufacturing | 2010 |
| Itrans Logistics Ltd | Transport & logistics | 2015 |
| Itrust Barnsley C.I.C. | Education | 2013 |
| Itsa Goal Posts Ltd | Manufacturing | 1986 |
| IULIAIULIA2007 Ltd | Manufacturing | 2025 |
| IVJ Driver Ltd | Construction | 2019 |
| IVY Cottage (Ackton) Ltd | Other services | 2000 |