| In-Cluded People Limited | Information & communication | 2021 |
| In-Stay Limited | Households | 2018 |
| Inaaya Cars Limited | Wholesale & retail | 2020 |
| Inaya Enterprise Limited | Wholesale & retail | 2025 |
| Inblack Consulting Ltd | Professional & scientific | 2018 |
| Incensed (UK) Ltd | Administrative & support | 2014 |
| Incensed Trading Limited | Administrative & support | 2017 |
| Includher CIC | Education | 2025 |
| Inclusive Care Options Ltd | Public administration | 2023 |
| Indelible Inc. Ltd | Information & communication | 2020 |
| Independent Consultancy Ltd | Information & communication | 2023 |
| Independent Legal Solutions Limited | Administrative & support | 2013 |
| Index Supply Ltd | Information & communication | 2024 |
| INDI28 Ltd | Real estate | 2021 |
| India Jane (Holdings) Ltd | Real estate | 2012 |
| India Jane (London) Limited | Wholesale & retail | 2018 |
| Indian Journalists' Association | Other services | 2009 |
| Indica Property Investments Limited | Real estate | 2023 |
| Indigene Limited | Professional & scientific | 2018 |
| Indigo 33 Limited | Other services | 2013 |
| Indigo ZEN Limited | Construction | 2002 |
| Indigofera PR Limited | Professional & scientific | 2009 |
| Indus Property Investments Limited | Real estate | 2021 |
| Industrie Clothing UK Ltd | Administrative & support | 2013 |
| Industry IOT Ltd | Administrative & support | 2017 |
| Ineedmoney Ltd | Wholesale & retail | 2023 |
| Infinitas Sport Ltd | Administrative & support | 2023 |
| Infinite DTO Ltd | Wholesale & retail | 2025 |
| Infinitiwave IT Solutions Ltd | Information & communication | 2023 |
| Infinity Four Properties Limited | Real estate | 2024 |
| Infinity Rising Limited | Professional & scientific | 2019 |
| Infopas Limited | Information & communication | 2008 |
| Informabiz Limited | Wholesale & retail | 2008 |
| Informaticians Limited | Information & communication | 2008 |
| Information System & Ecommerce Limited | Wholesale & retail | 2016 |
| Ingenxt Private Limited | Information & communication | 2019 |
| Inglis Music Limited | Arts & recreation | 2008 |
| Initial Software Services LLP | | 2020 |
| INK and Print Limited | Manufacturing | 2008 |
| INK N Toner UK Retail Limited | Wholesale & retail | 2004 |
| Inkluder CIC | Administrative & support | 2021 |
| Inkrea Limited | Wholesale & retail | 2020 |
| Inluster Limited | Arts & recreation | 2013 |
| Innervations Interior Contracts Limited | | 1990 |
| Innervision Limited | Real estate | 2000 |
| Innisowen Ltd. | Professional & scientific | 2025 |
| Innov Services Ltd | Other services | 2019 |
| Innovatethis Ltd | Administrative & support | 2020 |
| Innovation Manager Ltd | Other services | 2025 |
| Innso Group Limited | Administrative & support | 2018 |
| Inotech Prime Ltd | Information & communication | 2022 |
| Inside OUT Eventz Ltd | Hospitality | 2016 |
| Inside the Newsroom Ltd | Information & communication | 2020 |
| Insider Films Ltd | Information & communication | 2019 |
| Insight Alliance Ltd | Professional & scientific | 2023 |
| Insight Consultants Limited | Financial services | 2015 |
| Insightprocure Solutions Ltd | Professional & scientific | 2024 |
| Inskip & Davie Limited | Real estate | 2009 |
| Inspection Limited | Hospitality | 2001 |
| Inspiration Animation Ltd | Information & communication | 2024 |
| Inspiration Medical Ltd | Health & social care | 2005 |
| Inspire Homes (Frating) Ltd | Construction | 2024 |
| Inspire Homes Hurst Green Ltd | Construction | 2025 |
| Inspire Homes Investments Ltd | Construction | 2025 |
| Inspired Life (H) Ltd | Real estate | 2026 |
| Inspired Life (M) Ltd | Real estate | 2026 |
| Inspired Wellbeing Ltd | Health & social care | 2005 |
| Inspirit Paddington Bidco Limited | Other services | 2021 |
| Inspirit Travel, Trade & Education Services Ltd | Wholesale & retail | 2018 |
| Insta Organic Ltd | Professional & scientific | 2020 |
| Instant Games Consulting Limited | Information & communication | 2017 |
| Instant Home Sale Limited | Construction | 2006 |
| Instridea Limited | Information & communication | 2016 |
| Insufflate Limited | Construction | 2022 |
| Insurance Claims Accommodation Bureau Limited | Administrative & support | 2002 |
| Int'L Inc Ltd | Administrative & support | 2015 |
| INTEGR8 Limited | Administrative & support | 2005 |
| Integraite Limited | Information & communication | 2025 |
| Integrated Communications UK Limited | Information & communication | 2015 |
| Integrated Dermatology Limited | Health & social care | 2006 |
| Integreety Limited | Information & communication | 2012 |
| Integrit Ltd | Other services | 2016 |
| Integrity Funerals Limited | Other services | 2017 |
| Integrity Professionals Ltd | Professional & scientific | 2021 |
| Intelen Limited | Information & communication | 2017 |
| Intelligence Revolution Ltd | Information & communication | 2025 |
| Intelligent Accounting Solutions Limited | Professional & scientific | 2003 |
| Intelligent Digital Solutions Limited | Wholesale & retail | 2007 |
| Intelligent Estate Planning Solutions Ltd | Professional & scientific | 2016 |
| Intelligent Properties Limited | Real estate | 2011 |
| Intelligent Solutions 24 Limited | Information & communication | 2008 |
| Intercontinental Foods Ltd | Wholesale & retail | 2026 |
| Interhome Ltd | Real estate | 2021 |
| Interior Design Floors Ltd | Construction | 2014 |
| International Artists Market Limited | Wholesale & retail | 2000 |
| International Brain Tumour Alliance | Health & social care | 2006 |
| International Dance Rhythms Limited | Education | 2021 |
| International Golf Club London Ltd | Arts & recreation | 2020 |
| International House (CI) Ltd | Real estate | 2019 |
| Intespace (UK) Limited | Financial services | 2017 |