| Infinity Services (UK) Limited | Health & social care | 2014 |
| Infinity System Solutions Limited | Wholesale & retail | 2013 |
| Infinityqs Europe Limited | Information & communication | 2014 |
| Infocus Consultancy Ltd | Professional & scientific | 2024 |
| Infologic Services Limited | Information & communication | 1997 |
| Infopoint Systems Limited | Information & communication | 1991 |
| Infoshield Security Limited | Information & communication | 2025 |
| Infotree Consulting Limited | Other services | 2013 |
| Infowave Solutions Ltd | Information & communication | 2013 |
| Infra Market Ltd | Wholesale & retail | 2025 |
| Infracom Advisory Services Ltd | Professional & scientific | 2025 |
| Ingenuity IT Limited | Information & communication | 2003 |
| Ingun (UK) Limited | Wholesale & retail | 1991 |
| Inhabit Lifestyle Limited | Real estate | 2020 |
| Inhabit Realty Limited | Real estate | 2017 |
| Inis Group Limited | Real estate | 2021 |
| Initially Yours Limited | Wholesale & retail | 2002 |
| INK Bridge Ltd | Information & communication | 2025 |
| INK Finance Ltd | Information & communication | 2025 |
| INK Media Partners Ltd | Information & communication | 2025 |
| Inlet Recruitment Ltd | Administrative & support | 2026 |
| Inn-Trepid Enterprises Limited | Hospitality | 2003 |
| Innasons Limited | Professional & scientific | 2024 |
| Innate Digital Limited | Wholesale & retail | 2019 |
| Innocentgoblin Ltd | Information & communication | 2025 |
| Innovant Enterprise Ltd | Hospitality | 2020 |
| Innovate Audio Ltd | Information & communication | 2020 |
| Innovatiles Limited | Wholesale & retail | 2014 |
| Innovation and Insight Global Limited | Professional & scientific | 2019 |
| Innovation Creation Ltd | Manufacturing | 2014 |
| Innovation UN Limited | Professional & scientific | 2018 |
| Innovative Building Services & Maintenace Ltd | Construction | 2025 |
| Innovative Developers Ltd | Information & communication | 2014 |
| Innovative Estates (Brimingham ) Ltd | Real estate | 2012 |
| Inotech Professional Services Ltd | Professional & scientific | 2023 |
| Inova Marble Ltd | Manufacturing | 2026 |
| Inqubit Limited | Information & communication | 2025 |
| Inserve Marine Surveying Ltd | Professional & scientific | 2025 |
| Inside & OUT by RHK Limited | Hospitality | 2015 |
| Inside Finance Limited | Professional & scientific | 2008 |
| Inside Track Limited | Extraterritorial | 2025 |
| Insidemind Coaching Ltd | Health & social care | 2020 |
| Insider London Limited | Administrative & support | 2011 |
| Insight Accounting Ltd | Professional & scientific | 2008 |
| Insight Build Ltd | Construction | 2016 |
| Insight Build Property Ltd | Real estate | 2024 |
| Insight IVD Limited | Administrative & support | 2023 |
| Insight On-Boarding Limited | Professional & scientific | 2017 |
| Insight Property Diagnostics Ltd | Professional & scientific | 2026 |
| Insource Select Limited | Information & communication | 1997 |
| Inspire Children’S Day Nurseries Limited | Health & social care | 2025 |
| Inspire Fitness 121 Ltd | Other services | 2019 |
| Inspired by US Ltd | Wholesale & retail | 2014 |
| Inspiring Futures Partnership Trust | Education | 2012 |
| Inspiring Handz Ltd | Education | 2025 |
| Insta Build Solutions Ltd | Construction | 2016 |
| Installewa Ltd | Manufacturing | 2022 |
| Instant Mobile FIX Ltd | Manufacturing | 2022 |
| Instant Productions Limited | Information & communication | 2009 |
| Institute of Commerce Limited(The) | Education | 1908 |
| Intax Accountancy Limited | Professional & scientific | 2008 |
| Integral Commercial Services Limited | Professional & scientific | 1998 |
| Integrated Alarm Technology Services Limited | Other services | 1994 |
| Intelliforce Ltd | Information & communication | 2015 |
| Intellisolved Ltd | Transport & logistics | 2024 |
| Interactive Background Ltd | Transport & logistics | 2024 |
| Interactive Schools Ltd | Administrative & support | 2005 |
| Interasia Business Services Ltd | Administrative & support | 2016 |
| Intercert UK Limited | Extraterritorial | 2000 |
| Interform Manufacturing Limited | Manufacturing | 1984 |
| Interleave Ltd | Professional & scientific | 2022 |
| Interlink Technology Solutions Ltd | Construction | 2024 |
| International Women's Business Organisation Ltd | Professional & scientific | 2025 |
| International Benefits Network Limited | Financial services | 2001 |
| International British Development Experts Academy Limited | Education | 2019 |
| International Federation of Bookkeepers | Professional & scientific | 2012 |
| International Justice Consultancy Services Ltd | Professional & scientific | 2023 |
| International Qualification Forum Ltd | Education | 2023 |
| International Skill Development Corporation Limited | Education | 2013 |
| Interpak Ltd | Wholesale & retail | 2001 |
| Interpart Motor Spares Limited | Wholesale & retail | 2003 |
| Interpractive NC Ltd | Professional & scientific | 2024 |
| Interstellar Property Investments Ltd | Hospitality | 2019 |
| Intinvestproperty Ltd | Construction | 2024 |
| Intrafix Ltd | Construction | 2007 |
| Inveni Fitness Ltd | Arts & recreation | 2024 |
| Invenio Training Limited | Education | 2014 |
| Inventology Limited | Administrative & support | 2008 |
| Inventure Ashton Ltd | Wholesale & retail | 2019 |
| Inventure Camden Ltd | Wholesale & retail | 2023 |
| Inventure CHS Ltd | Wholesale & retail | 2025 |
| Inventure Circle Ltd | Wholesale & retail | 2024 |
| Inventure ECR Ltd | Wholesale & retail | 2021 |
| Inventure Holdings Limited | Professional & scientific | 2015 |
| Inventure Kensington Limited | Wholesale & retail | 2013 |
| Inventure Old Street Ltd | Wholesale & retail | 2019 |
| Inventure Properties Ltd | Real estate | 2020 |
| Inventure Putney Ltd | Wholesale & retail | 2014 |
| Inventure Retail Ltd | Wholesale & retail | 2010 |
| Inventure Soho Ltd | Wholesale & retail | 2019 |