| Inside OUT DD Ltd | Wholesale & retail | 2024 |
| Inside Recruiters Ltd | Administrative & support | 2018 |
| Inside the Script Ltd | Information & communication | 2016 |
| Insideguide Ltd | Professional & scientific | 2019 |
| Insideout Design + Build Limited | Construction | 2019 |
| Insideout Support Wales C.I.C. | Education | 2019 |
| Insig International Limited | Wholesale & retail | 2021 |
| Insight Accountancy & Consultants Limited | Information & communication | 2019 |
| Insight Cartons (Realisations) Limited | Professional & scientific | 1981 |
| Insight Creative Media Ltd | Administrative & support | 2018 |
| Insight Elite & Strategy Ltd | Information & communication | 2023 |
| Insight FD Limited | Administrative & support | 2026 |
| Insight Gateway Ltd | Information & communication | 2012 |
| Insight Insurance Services Ltd | Financial services | 2002 |
| Insight Legal Services Limited | Professional & scientific | 2017 |
| Insight Resources Limited | Professional & scientific | 2015 |
| Insight Unleashed Ltd | Information & communication | 2026 |
| Insight Wales Consulting Limited | Professional & scientific | 2012 |
| Insightatoz Consulting Ltd | Professional & scientific | 2019 |
| Insightful Analytical Ltd | Information & communication | 2025 |
| Insightiq Solutions Limited | Transport & logistics | 2024 |
| Insignia Bloomers Limited | Wholesale & retail | 2020 |
| Insite AV Artistry Limited | Information & communication | 2024 |
| Insite M & a Limited | Professional & scientific | 2023 |
| Insite Trading Ltd | Professional & scientific | 2025 |
| Insitu AI Limited | Information & communication | 2025 |
| Insketch Limited | Professional & scientific | 2019 |
| Insole Court Trading Company Ltd | Administrative & support | 2018 |
| Insole Court Trust-Ymddiredolaeth Cwrt Insole | Administrative & support | 2011 |
| Insolv Assist Limited | Financial services | 2026 |
| Insomniac Ltd | Hospitality | 2024 |
| Inspace Architects Ltd | Professional & scientific | 2020 |
| Inspec-Ts Global Ltd | Mining & quarrying | 2020 |
| Inspect (Wales) Ltd | Construction | 2005 |
| Inspection Point Limited | Professional & scientific | 2016 |
| Inspector Leak Ltd | Professional & scientific | 2015 |
| Inspination CIC | Health & social care | 2025 |
| Inspira Edge Ltd | Other services | 2019 |
| Inspiratek Medical Ltd | Professional & scientific | 2016 |
| Inspiration Capital Investments Ltd | Hospitality | 2014 |
| Inspiration Sales Ltd | Wholesale & retail | 2023 |
| Inspiration Wealth Management Limited | Administrative & support | 2004 |
| Inspirational Lighting and Electrical Supplies Ltd | Wholesale & retail | 2005 |
| Inspirational Mindset Limited | Other services | 2016 |
| Inspirations by Alona Ltd | Wholesale & retail | 2023 |
| Inspire Delta Solutions Ltd | Professional & scientific | 2025 |
| Inspire Dental Excellence Academy Ltd | Education | 2023 |
| Inspire Film & Television Ltd | Information & communication | 2017 |
| Inspire Green Ltd | Construction | 2012 |
| Inspire Growth Wales LLP | | 2015 |
| Inspire Holdcoo Limited | Real estate | 2025 |
| Inspire Hospitality Solutions Limited | Administrative & support | 2017 |
| Inspire Interior Retail Ltd | Wholesale & retail | 2019 |
| Inspire International Development Corporation Limited | Construction | 2019 |
| Inspire Investment Holdings Ltd | Financial services | 2010 |
| Inspire Neurodiversity and Wellbeing CIC | Education | 2025 |
| Inspire Tax & Estate Planning LLP | | 2013 |
| Inspire Windows Ltd | Construction | 2010 |
| Inspirechem Ltd | Real estate | 2015 |
| Inspired B2B Marketing Limited | Administrative & support | 2017 |
| Inspired by KEN Limited | Wholesale & retail | 2024 |
| Inspired HR Services Ltd | Wholesale & retail | 2021 |
| Inspired Kitchen Ltd | Hospitality | 2020 |
| Inspired Lifestyle Brands Ltd | Wholesale & retail | 2019 |
| Inspired Products Group Ltd | Financial services | 2021 |
| Inspired Thought Ltd | Professional & scientific | 2020 |
| Inspiretec Group Limited | Financial services | 2014 |
| Inspiretec Ltd | Information & communication | 1995 |
| Inspirez Limited | Administrative & support | 2019 |
| Inspiritfintech Ltd. | Information & communication | 2017 |
| Inspirometer Limited | Information & communication | 2012 |
| Inspo&Home Ltd | Hospitality | 2023 |
| Inspop.Com Limited | Information & communication | 1999 |
| Inst@Build Ltd | Construction | 2019 |
| Insta Cars London Ltd | Wholesale & retail | 2018 |
| Insta Link Ltd | Information & communication | 2025 |
| Insta Support Ltd | Health & social care | 2018 |
| Instaabuy Ltd | Wholesale & retail | 2025 |
| Instaal Limited | Information & communication | 2022 |
| Installec Ltd | Construction | 2017 |
| Instamoni Limited | Professional & scientific | 2016 |
| Instanery LLP | | 2021 |
| Instant Advisors PC | | 2014 |
| Instant Business Communications Ltd | Information & communication | 2019 |
| Instant Exchange UK Limited | Financial services | 2003 |
| Instant Health Data Limited | Professional & scientific | 2012 |
| Instant Karma(Uk) Limited | Construction | 2025 |
| Instant Recruit Ltd | Other services | 2018 |
| Instant Solution Property & Insure Ltd | Construction | 2018 |
| Instant Solutionz Property & Insure Ltd | Transport & logistics | 2017 |
| Instantpay Ltd | Information & communication | 2025 |
| Instaplay Ltd | Construction | 2019 |
| Instarooms London Ltd | Real estate | 2019 |
| Instigate B2B Ltd | Professional & scientific | 2019 |
| Instigate IP Limited | Administrative & support | 2023 |
| Instinct Scooter Parts Ltd | Manufacturing | 2023 |
| Instinctive Design Ltd | Professional & scientific | 2024 |
| Institute of British Sign Language | Education | 2007 |
| Institute of Healthcare Management Ltd. | Other services | 2016 |
| Institute of Welsh Affairs | Other services | 1987 |