| Intermotor Holdings Limited | Manufacturing | 2015 |
| International Bio-Based Material & Buildings Limited | Professional & scientific | 2016 |
| International Celebrity Networks Limited | Administrative & support | 2009 |
| International Centre for Negotiation Limited | Professional & scientific | 2017 |
| International Communication & Data Limited | Professional & scientific | 1983 |
| International Development Foundation for Community Integration & Support Services CIC | Professional & scientific | 2015 |
| International Education Enterprise | Education | 2011 |
| International Event Crew Ltd | Administrative & support | 2019 |
| International Expert Consultants Ltd | Professional & scientific | 2019 |
| International Global Consulting Ltd | Professional & scientific | 2021 |
| International Insights for Entrepreneurship Ltd | Education | 2019 |
| International Society of Engineering Science and Technology | Information & communication | 2019 |
| International Sports Engineering Association | Education | 2017 |
| International Step Dance Academy Community Interest Company | Other services | 2024 |
| International Students Unity | Education | 2025 |
| International UNI of London Ltd | Education | 2026 |
| International Union of Professional Trainers Ltd | Education | 2021 |
| Internet Advertising Services Limited | Information & communication | 2000 |
| Internet Expert Ltd | Information & communication | 2007 |
| Internet Motor Parts Limited | Wholesale & retail | 2015 |
| Internet Profits Limited | Wholesale & retail | 2010 |
| Interphase Limited | Construction | 2018 |
| Interpro Expediting Ltd | Construction | 2015 |
| Interscope Properties Limited | Real estate | 2021 |
| Interscope Solutions Ltd | Wholesale & retail | 2003 |
| Intersect Education Ltd | Education | 2024 |
| Interservo 24 Limited | Manufacturing | 2020 |
| Interstella Logistics Ltd | Transport & logistics | 2025 |
| Intertex Group Limited | Administrative & support | 2019 |
| Intertrode Limited | Information & communication | 2012 |
| Into M&E Solutions Ltd | Construction | 2015 |
| Into Skin Ltd | Arts & recreation | 2004 |
| Into the Forest Ltd | Arts & recreation | 2018 |
| Intoware Ltd | Information & communication | 2015 |
| Intozetta Holdings Limited | Financial services | 2019 |
| Intozetta Limited | Administrative & support | 2016 |
| Intra Wellbeing Limited | Other services | 2021 |
| Intram Chemicals Limited | Manufacturing | 2009 |
| Intratek Ltd | Information & communication | 2023 |
| Intrinsic 360 Group Ltd | Professional & scientific | 2019 |
| Introinnovative Consulting (UK) Limited | Information & communication | 2016 |
| Intygra Holdings Limited | Manufacturing | 2014 |
| Intygra Limited | Manufacturing | 2005 |
| Intygra Trustees Limited | Extraterritorial | 2005 |
| Inui Ltd | Manufacturing | 2011 |
| Inukshuk Strategy Limited | Professional & scientific | 2020 |
| INURSE24 Healthcare Staffing Limited | Health & social care | 2017 |
| Inval Holdings Limited | Financial services | 1965 |
| Inventa Public Sector Ltd | Administrative & support | 2019 |
| Inventa Therapeutics Limited | Professional & scientific | 2017 |
| Inventacinema Limited | Construction | 2022 |
| INVENTORIES4YOU Limited | Households | 2022 |
| Inveraden Properties Ltd | Extraterritorial | 2019 |
| Inverhome Limited | Health & social care | 1985 |
| Inverness Stars Ltd | Health & social care | 2025 |
| Inversetulip Ltd | Wholesale & retail | 2024 |
| Invest for Change Ltd | Financial services | 2021 |
| Invest in Nottingham Limited | Extraterritorial | 2015 |
| Investasearch Limited | Administrative & support | 2018 |
| Invested in Gyms Limited | Professional & scientific | 2026 |
| Invested in Property Ltd | Real estate | 2023 |
| Investigation Limited | Administrative & support | 2002 |
| Investment Choices Wealth Management Ltd | Extraterritorial | 2008 |
| Investment Holmes Limited | Real estate | 2017 |
| Investment Ilkeston LLP | | 2017 |
| Investment Sense Limited | Financial services | 2009 |
| Invicta Legacy Services LLP | | 2011 |
| Invicta Neon Ltd | Manufacturing | 2000 |
| Invictus Activewear Ltd | Wholesale & retail | 2024 |
| Invictus Electrical Installations Services Limited | Construction | 2024 |
| Invictus Home Solutions Limited | Administrative & support | 2019 |
| Invictus IFA Ltd | Financial services | 2015 |
| Invictus Legal (UK) LLP | | 2010 |
| Invictus Legal Services Ltd | Professional & scientific | 2018 |
| Invincible Rubber Limited | Financial services | 2021 |
| Invinciblegp Ltd | Health & social care | 2025 |
| Invisible Pixel Limited | Professional & scientific | 2016 |
| Invisible Touch Tanning and Beauty Ltd | Other services | 2007 |
| Invitation Publishing Limited | Information & communication | 2018 |
| Invoke Gymnastics Club Ltd | Arts & recreation | 2020 |
| Invoke Gymnastics Services Ltd | Arts & recreation | 2018 |
| Involved Care Ltd | Health & social care | 2021 |
| Involved Holidays Limited | Administrative & support | 2020 |
| Involving Communities Ltd | Administrative & support | 2009 |
| Inwood Furniture Limited | Wholesale & retail | 2005 |
| Inyourplace Ltd | Wholesale & retail | 2011 |
| ION Consulting Engineers Limited | Professional & scientific | 2004 |
| IOS Construct Limited | Construction | 2025 |
| IOS Direct Limited | Professional & scientific | 2007 |
| Iota Automation Ltd | Manufacturing | 2023 |
| IP NET Services Ltd | Information & communication | 2022 |
| Ipaint Limited | Wholesale & retail | 2022 |
| IPB Training Limited | Administrative & support | 2005 |
| Ipeppes Limited | Hospitality | 2025 |
| Iperian Limited | Information & communication | 2002 |
| Iphie Pearl Limited | Health & social care | 2024 |
| IPK Healthcare Services Limited | Health & social care | 2023 |
| IPS Fire and Security Ltd. | Administrative & support | 2004 |
| IPS Pearce Ltd | Construction | 2012 |
| IPS Systems Ltd | Professional & scientific | 2024 |