| Innperium Ltd | Professional & scientific | 2012 |
| Inone Holdings Limited | Professional & scientific | 1996 |
| Inova Homes Ltd | Construction | 2016 |
| Inova Solutions Consultancy Ltd | Professional & scientific | 2024 |
| Inovahr Consulting Ltd | Construction | 2026 |
| Inovahr Ltd | Construction | 2025 |
| Inovanov Engineering Limited | Construction | 2016 |
| Inprint & Design Limited | Information & communication | 2001 |
| Input IT Ltd | Agriculture & fishing | 2003 |
| Insave Group Ltd | Professional & scientific | 2017 |
| Insect Armour Ltd | Water & waste | 2021 |
| Insectology Limited | Manufacturing | 2024 |
| Inseego Finance Limited | Information & communication | 2004 |
| Inside Edge Interiors Limited | Construction | 2023 |
| Inside-Out Properties Limited | Real estate | 2005 |
| Insight & Automation Ltd | Information & communication | 2020 |
| Insight and Design Group Limited | Information & communication | 2022 |
| Insight Commercial Finance Limited | Professional & scientific | 2019 |
| Insight Controls Limited | Manufacturing | 2026 |
| Insight Eating & Insight Health Limited | Health & social care | 2021 |
| Insight Education Partnership Ltd | Education | 2024 |
| Insight Health Projects Limited | Health & social care | 2022 |
| Insight Holiday Lets Ltd | Real estate | 2003 |
| Insight HR Consultancy Limited | Professional & scientific | 2022 |
| Insight OUT Solutions Limited | Administrative & support | 2014 |
| Insight Studios Limited | Information & communication | 2011 |
| Insight Talent Partners Ltd | Administrative & support | 2023 |
| Insight Testing Limited | Information & communication | 2010 |
| Insight Therapeutic Services Ltd | Other services | 2022 |
| Insight Therapy Centre Limited | Administrative & support | 2015 |
| Insightova Limited | Information & communication | 2025 |
| Insights Management Consulting Ltd | Information & communication | 2023 |
| Insightwave Limited | Wholesale & retail | 2017 |
| Insolvency One Limited | Professional & scientific | 2020 |
| Insolvency Options Ltd | Financial services | 2018 |
| Inspan Securities Limited | Real estate | 1972 |
| Inspirational Counselling Ltd | Health & social care | 2018 |
| Inspirational Financial Management Ltd | Financial services | 1998 |
| Inspirations Dance Ltd | Arts & recreation | 2021 |
| Inspirations Nurseries and Forest School Limited | Health & social care | 1999 |
| Inspiratus Ltd | Professional & scientific | 2025 |
| Inspire (LIA) Ltd | Education | 2025 |
| Inspire Case Management Limited | Health & social care | 2025 |
| Inspire Consultancy Services Limited | Administrative & support | 2005 |
| Inspire Educational Psychology Limited | Professional & scientific | 2020 |
| Inspire Holdings (Durham) Ltd | Hospitality | 2023 |
| Inspire Investments Group Ltd | Hospitality | 2021 |
| Inspire Language Education Ltd | Education | 2025 |
| Inspire M Education Ltd | Education | 2024 |
| Inspire PVT Ltd | Wholesale & retail | 2025 |
| Inspire SB Ltd | Arts & recreation | 2020 |
| Inspired by Theatre Ltd | Arts & recreation | 2026 |
| Inspired Collaborative Ltd | Education | 2023 |
| Inspired Furniture 4U Ltd | Wholesale & retail | 2024 |
| Inspired Homes & Build Ltd | Construction | 2020 |
| Inspired Investments Unlimited | Financial services | 2025 |
| Inspired PD Ltd | Education | 2021 |
| Inspired Property Group Investments Ltd | Real estate | 2021 |
| Inspired Property Lettings Ltd | Real estate | 2022 |
| Inspired Site Safety Ltd | Professional & scientific | 2019 |
| Inspired Training & Consultancy Limited | Administrative & support | 2010 |
| Inspired-Nation CIC | Health & social care | 2022 |
| Inspiredby:Creative Solutions Limited | Administrative & support | 2003 |
| Inspiredspaces Rochdale (HOLDINGS1) Limited | Professional & scientific | 2009 |
| Inspiredspaces Rochdale (HOLDINGS2) Limited | Professional & scientific | 2012 |
| Inspiredspaces Rochdale (PROJECTCO1) Limited | Administrative & support | 2009 |
| Inspiredspaces Rochdale (PROJECTCO2) Limited | Administrative & support | 2012 |
| Inspireone Property Group Ltd | Real estate | 2025 |
| Inspiring Choices | Education | 2015 |
| Inspiring Image Ltd | Other services | 2008 |
| Inspiring People Development Ltd | Other services | 2015 |
| Inspiring Positive Futures CIC | Professional & scientific | 2017 |
| Insports Technologies Ltd | Information & communication | 2025 |
| Insta Booze Leeds Limited | Wholesale & retail | 2019 |
| Instabiz Ltd | Wholesale & retail | 2025 |
| Instant Mentors Ltd | Professional & scientific | 2021 |
| Instaplanta (Yorkshire) Limited | Manufacturing | 2010 |
| Insteach Limited | Information & communication | 2024 |
| Instil Consulting Limited | Professional & scientific | 2020 |
| Instil Limited | Administrative & support | 2005 |
| Instinct Design (Yorkshire) Ltd | Wholesale & retail | 2016 |
| Institute of Meat | Other services | 2010 |
| Instock Carpets and Flooring Ltd | Wholesale & retail | 2023 |
| Instore Direct Ltd | Wholesale & retail | 2001 |
| Instrumentation Systems & Services Limited | Construction | 2015 |
| Instyle Bridal Fashions Limited | Wholesale & retail | 2024 |
| Instyle Construction Limited | Wholesale & retail | 1989 |
| Instyle Harrogate Ltd | Professional & scientific | 2022 |
| Insulate Nationwide Limited | Other services | 2019 |
| Insurance for Ltd | Financial services | 2015 |
| Insure OUR Event Limited | Extraterritorial | 2017 |
| Insuresme Limited | Extraterritorial | 2023 |
| Inswift Ltd | Wholesale & retail | 2023 |
| Intceram Limited | Wholesale & retail | 2001 |
| Intech Systems Group Ltd | Wholesale & retail | 1995 |
| Intechnical Ltd | Professional & scientific | 2019 |
| Intechnology PLC | Information & communication | 2000 |
| Integra Housing Consultancy Ltd | Professional & scientific | 2007 |
| Integra Insurance Solutions Limited | Financial services | 2008 |
| Integra Motors Ltd | Wholesale & retail | 2023 |