| Indira Medicals Ltd | Health & social care | 2023 |
| Indisiscrafts Ltd | Wholesale & retail | 2025 |
| Indisputable Ltd | Administrative & support | 2025 |
| Indium Consulting Limited | Information & communication | 2023 |
| Individual Living Ltd | Manufacturing | 2020 |
| Indr Ltd | Information & communication | 2018 |
| Induscan Inspection Services Ltd | Wholesale & retail | 2025 |
| Industrial Projects Services UK Limited | Construction | 2022 |
| Infection Care UK Ltd | Health & social care | 2025 |
| Infinite Business Consulting Ltd | Administrative & support | 2025 |
| Infinite Compliance Ltd | Administrative & support | 2022 |
| Infinite Property Ltd | Professional & scientific | 2008 |
| Infinite Property Maintenance Ltd | Administrative & support | 2022 |
| Infinitectrl Ltd | Wholesale & retail | 2025 |
| Infiniti Salon Ltd | Other services | 2020 |
| Infinity Risk Management Ltd | Professional & scientific | 2019 |
| Infinity Tech Consulting Ltd | Information & communication | 2023 |
| Infinitydogtreats Ltd | Wholesale & retail | 2025 |
| Inflection Ltd | Professional & scientific | 2025 |
| Influx Solutions Ltd | Construction | 2026 |
| Infographtec Ltd | Information & communication | 2018 |
| Infopoly Limited | Information & communication | 2020 |
| Information Journeys Limited | Professional & scientific | 2016 |
| Infosys Tech Group Limited | Information & communication | 2023 |
| Infrastructure Automation Limited | Information & communication | 2015 |
| Infratek Solutions Limited | Administrative & support | 2014 |
| Infused Jars Ltd | Manufacturing | 2023 |
| Infusion Events Limited | Arts & recreation | 2017 |
| Ingeniosity Ltd | Professional & scientific | 2022 |
| Ingenium Engineering Services Ltd | Administrative & support | 2026 |
| Ingevity UK Ltd | Manufacturing | 1992 |
| Ingrace Solutions PVT Limited | Information & communication | 2014 |
| Ingram Agility Limited | Professional & scientific | 2017 |
| Inicio Academies Ltd | Extraterritorial | 2024 |
| Inicio Children's Residential (the Woodlands) Ltd | Health & social care | 2024 |
| Inicio Children's Residential Ltd | Health & social care | 2024 |
| Inicio Community Support Ltd | Health & social care | 2023 |
| Inicio Conferences Ltd | Extraterritorial | 2024 |
| Inicio Education Ltd | Education | 2024 |
| Inicio Events Ltd | Arts & recreation | 2023 |
| Inicio Families First Ltd | Health & social care | 2025 |
| Inicio Family Assessments Ltd | Health & social care | 2023 |
| Inicio Fostering Ltd | Health & social care | 2023 |
| Inicio Group Ltd | Health & social care | 2016 |
| Inicio Healthy Minds Ltd | Health & social care | 2023 |
| Inicio Property Holdings Limited | Real estate | 2018 |
| Inicio Social Housing Ltd | Health & social care | 2023 |
| Inicio Support Ltd | Professional & scientific | 2024 |
| Inicio Supported Accommodation Ltd | Health & social care | 2023 |
| Inicio Supported Living Ltd | Health & social care | 2023 |
| Inicio Supported Lodgings Ltd | Health & social care | 2023 |
| Inicio Training & Consultancy Ltd | Professional & scientific | 2023 |
| Initus Ltd. | Administrative & support | 2012 |
| Inkbox Print Ltd | Manufacturing | 2018 |
| Inman Electrical Solutions Limited | Construction | 2024 |
| Innerharbour Limited | Professional & scientific | 2017 |
| Innervoyage Ltd | Education | 2025 |
| Innes Consulting Limited | Professional & scientific | 2025 |
| INNOV8 Products Ltd | Extraterritorial | 2015 |
| Innova Grants Ltd | Professional & scientific | 2021 |
| Innova Investment Holdings Limited | Financial services | 2024 |
| Innovate & Deliver Limited | Professional & scientific | 2014 |
| Innovate Construction NW Limited | Construction | 2019 |
| Innovation First International(Uk) Limited | Professional & scientific | 2002 |
| Innovation Ltd | Professional & scientific | 2023 |
| Innovative Embedded Solutions Limited | Information & communication | 2021 |
| Innovative Environmental Solutions UK Ltd | Manufacturing | 2008 |
| Innovative Social Limited | Professional & scientific | 2025 |
| Innovolve Ltd | Information & communication | 2025 |
| Inox Filters Limited | Administrative & support | 2011 |
| Inphinity Management Limited | Professional & scientific | 2019 |
| Inprojects Consultancy Ltd | Administrative & support | 2025 |
| Inprova Group Ltd | Professional & scientific | 2014 |
| Inprova Ltd | Wholesale & retail | 2010 |
| Inprova Procurement Limited | Other services | 2018 |
| Insagua Ltd | Information & communication | 2022 |
| Insight Business Advisers Limited | Professional & scientific | 2014 |
| Insight Planning Services Ltd | Administrative & support | 2021 |
| Insight Sky Global Ltd | Hospitality | 2025 |
| Insightful AI Solutions Limited | Information & communication | 2025 |
| Insights Healthcare Limited | Manufacturing | 2024 |
| Insights IT Solutions Limited | Information & communication | 2023 |
| Insignia Spaces Ltd | Construction | 2024 |
| Insignis Technologies Limited | Administrative & support | 2016 |
| Insinc Media Limited | Information & communication | 2017 |
| Inspectacoat Limited | Professional & scientific | 2026 |
| Inspira Finance Ltd | Administrative & support | 2025 |
| Inspire (Structures) Limited | Professional & scientific | 2013 |
| Inspire Benefits Limited | Financial services | 2013 |
| Inspire Inclusion 4 Send Community Interest Company | Health & social care | 2025 |
| Inspired Access Solutions Ltd | Professional & scientific | 2020 |
| Inspired Design & Print Ltd | Manufacturing | 2013 |
| Inspired Marketing Lifestyle Limited | Wholesale & retail | 2023 |
| Inspired Tax Solutions Limited | Professional & scientific | 2017 |
| Inst Control Ltd | Administrative & support | 2009 |
| Install Creations Limited | Administrative & support | 2022 |
| Installation Maintenance Solutions Limited | Professional & scientific | 2013 |
| Installex Ltd | Construction | 2025 |
| Institute of Economic Development | Administrative & support | 1983 |
| Institute of Event Management | Professional & scientific | 2012 |