| Indigo Neuro Limited | Health & social care | 2019 |
| Indigo Neuropsychology Limited | Health & social care | 2026 |
| Industrial Coatings North East Limited | Construction | 2015 |
| Industrial Solutions Group (UK) Ltd | Professional & scientific | 2026 |
| Indyforbesgroup Ltd | Real estate | 2020 |
| Infacloud Limited | Information & communication | 2026 |
| Infection Control International Limited | Manufacturing | 2016 |
| Infinite Wealth Group Limited | Professional & scientific | 2016 |
| Infinity Finance Group Limited | Professional & scientific | 2019 |
| Infinity Property North East Ltd | Real estate | 2020 |
| Inflate & Play Ltd | Administrative & support | 2020 |
| Influence Cafe LLP | | 2018 |
| Infosec Governance Ltd | Information & communication | 2019 |
| Infrasense Limited | Information & communication | 2020 |
| Ingleby Lettings Ltd | Real estate | 2023 |
| Ingledews Jewellers Ltd | Wholesale & retail | 2018 |
| Inglett Ltd | Wholesale & retail | 2022 |
| INK Bear Ltd | Professional & scientific | 2018 |
| INK Exchange Ltd | Wholesale & retail | 2002 |
| INK Marketing Group Ltd | Professional & scientific | 2022 |
| Inkwell Creative Ltd | Information & communication | 2026 |
| Innovative Animal Supplies Ltd | Professional & scientific | 2021 |
| Innstranet Services Ltd | Information & communication | 2024 |
| Inspirar Business Support Limited | Information & communication | 2011 |
| Inspire IDP Ltd | Information & communication | 2025 |
| Installation & Manufacturing Contractors Limited | Manufacturing | 1961 |
| Institute of Enterprise and Entrepreneurs Limited | Other services | 2010 |
| Insulation Environmental Training Trust Limited | Education | 1991 |
| Intake VHQ Limited | Professional & scientific | 2025 |
| Integrated Electronic Security Ltd | Administrative & support | 2002 |
| Integrated Mental Health Care Services Limited | Other services | 2015 |
| Integritify Group Services Ltd | Wholesale & retail | 2026 |
| Inteleforge Limited | Information & communication | 2025 |
| Intelligence Resource LAB Limited | Administrative & support | 2015 |
| Interactive Projects & Design Limited | Construction | 2003 |
| Intercept Intelligence Partners Ltd | Information & communication | 2026 |
| Interiors Carpenter Wood Ltd | Construction | 2019 |
| International Developments & Consultancy Ltd | Construction | 2025 |
| Internationally Wingin IT Ltd | Financial services | 2019 |
| Into Painting & Decorating Ltd | Construction | 2021 |
| Into Property Development Ltd | Real estate | 2025 |
| Intrepid Solutions Limited | Professional & scientific | 2023 |
| Intuition Languages Limited | Education | 1992 |
| INU Music Ltd | Information & communication | 2026 |
| Iodem Limited | Health & social care | 2010 |
| Iodem Properties Limited | Real estate | 2014 |
| Ioee International Ltd | Education | 2025 |
| Ioee Ltd | Administrative & support | 2014 |
| ION Precision Engineering Limited | Extraterritorial | 2015 |
| IPS Contractors Ltd | Construction | 2016 |
| IQ Building Services Ltd | Construction | 2016 |
| Ireach Minds Limited | Education | 2017 |
| Iron Paths Ltd | Information & communication | 2025 |
| Irshad IR Limited | Professional & scientific | 2018 |
| Irvinfx (IFX) Ltd | Information & communication | 2022 |
| Iryan Transport Logistic Ltd | Wholesale & retail | 2025 |
| Isaiah 14:24 Limited | Hospitality | 2024 |
| Iscor Training Ltd | Education | 2018 |
| ISG Facility Management Ltd | Construction | 2025 |
| Islam (New Reema) Ltd | Hospitality | 2019 |
| Islam Tandoori Limited | Hospitality | 2021 |
| Istanbul Barber NE Limited | Other services | 2024 |
| IT Systems & Support Limited | Information & communication | 2014 |
| It's a Small World Designer Childrenswear Ltd | Wholesale & retail | 2012 |
| Itradegroup Ltd | Administrative & support | 2023 |
| ITS a Graze Life Limited | Hospitality | 2026 |
| Ives Product Design Limited | Professional & scientific | 2017 |
| Iveson Developments Ltd | Real estate | 2025 |
| IVY Cottage Limited | Hospitality | 2019 |
| IVY Technology Ltd | Administrative & support | 2020 |
| Iyawa Continental Ltd | Hospitality | 2024 |
| J & C Boardline Ltd | Construction | 2015 |
| J & H Property and Developments Ltd | Construction | 2013 |
| J & J Haulage Limited | Transport & logistics | 2020 |
| J & L Holiday Lets Ltd | Hospitality | 2021 |
| J & M Enterprises (N/E) Ltd | Wholesale & retail | 2013 |
| J & M Furnishings Limited | Manufacturing | 2013 |
| J & R M Investments Limited | Real estate | 2013 |
| J &P Project Management Ltd | Construction | 2025 |
| J a & M Boyes Limited | Agriculture & fishing | 2010 |
| J a Jemmeson Ltd | Mining & quarrying | 2023 |
| J B F Building Contractors Ltd | Construction | 2019 |
| J C Gill & Co Limited | Professional & scientific | 2009 |
| J Electrical Limited | Construction | 1998 |
| J Ents Transport Ltd | Wholesale & retail | 2024 |
| J Foster Building Services Ltd | Construction | 2015 |
| J Harland Haulage Limited | Transport & logistics | 2003 |
| J K Racing Limited | Professional & scientific | 1997 |
| J L Services (NE) Limited | Professional & scientific | 2019 |
| J M Wilson & SON Ltd | Construction | 2010 |
| J P Jackson Ltd | Professional & scientific | 2012 |
| J P W Trading Ltd | Wholesale & retail | 2015 |
| J P Walters & Co Ltd | Professional & scientific | 2010 |
| J R & S Leisure Ltd | Arts & recreation | 2025 |
| J R Brown Haulage Services | Transport & logistics | 2026 |
| J R Humble Building Services Ltd | Construction | 2022 |
| J R Maritime & Security Consultants Ltd | Professional & scientific | 2024 |
| J R Stephenson Aggregates Ltd | Wholesale & retail | 2024 |
| J R Stephenson Landscaping Ltd | Administrative & support | 2022 |
| J Robinson Developments Ltd | Construction | 2024 |