| Ingleby Barwick Property Services Ltd | Other services | 2020 |
| Ingleby Barwick Windows Doors and Conservatories Ltd | Construction | 2019 |
| Ingleby Electronics N.E. Limited | Manufacturing | 2024 |
| Ingleby Glazing Limited | Other services | 2013 |
| Ingleby Healthcare Ltd | Administrative & support | 2011 |
| Ingleby Homes Ltd | Real estate | 2016 |
| Ingleby Motor Group Ltd | Wholesale & retail | 2025 |
| Ingleby Piping Solutions Limited | Construction | 2024 |
| Ingleby Renewable Solutions Limited | Extraterritorial | 2024 |
| Ingleby Renovations Limited | Construction | 2022 |
| Ingleby Signs & Print Ltd | Manufacturing | 2025 |
| Ingreen Architectural Solutions Limited | Professional & scientific | 2011 |
| Inho Ltd | Wholesale & retail | 2026 |
| Injurbee Prevention and Rehabilitation Ltd | Other services | 2025 |
| Inligo Limited | Real estate | 2022 |
| Inline Water Treatment Co. Limited | Professional & scientific | 1991 |
| Innersummit Ltd | Professional & scientific | 2012 |
| Innomersive Ltd | Information & communication | 2023 |
| Innovarie Ltd | Information & communication | 2024 |
| Innovation Court Management Company Limited | Administrative & support | 2008 |
| Innovation Developments NE Ltd | Construction | 2023 |
| Innovation Martial Arts Ltd | Arts & recreation | 2016 |
| Innovations Advanced Skincare Beauty Limited | Other services | 2015 |
| Inotu Holdings Limited | Financial services | 2024 |
| Ins-Spec Ltd | Manufacturing | 2019 |
| Inside Outside Community Development CIC | Health & social care | 2016 |
| Inspect Pro Limited | Information & communication | 2023 |
| Inspiration Salons Ltd | Other services | 2008 |
| Inspirations Hartburn Ltd | Other services | 2011 |
| Inspire FBW Limited | Professional & scientific | 2022 |
| Inspiron Learning CIC | Education | 2022 |
| Instrumentation Electrical Services Limited | Administrative & support | 2000 |
| Instrumentation Technical Services Ltd | Professional & scientific | 2020 |
| Instyle Landscape Design and Build Ltd | Administrative & support | 2021 |
| Insurance Advisory Group Limited | Financial services | 2014 |
| Intasite Holdings Ltd. | Information & communication | 2020 |
| Intasite Ltd | Information & communication | 2015 |
| Intasite Solutions Limited | Information & communication | 2023 |
| Interim Management Solutions Worldwide Limited | Administrative & support | 2000 |
| Interiors Teesside Ltd | Manufacturing | 2022 |
| Interlude Clothing Ltd | Wholesale & retail | 2024 |
| Intermat Limited | Hospitality | 2006 |
| International Contracting Services Ltd | Construction | 2024 |
| International Processplants (Europe) Limited | Manufacturing | 1975 |
| Into Touch Properties Ltd | Real estate | 2023 |
| Inventing X Ltd | Financial services | 2021 |
| Inventors Tech Ltd | Professional & scientific | 2023 |
| Invest One NE Ltd | Administrative & support | 2018 |
| Invictus Films Limited | Information & communication | 1992 |
| Invictus Media & Marketing Ltd | Information & communication | 2024 |
| Inzu Prime Ventures Ltd | Real estate | 2024 |
| Iota Manufacturing Limited | Manufacturing | 2020 |
| IP Contracts Solutions Limited | Professional & scientific | 2010 |
| IP Property Investments Ltd | Real estate | 2023 |
| IPQ Solutions Limited | Professional & scientific | 2025 |
| IPS Electec CMA Ltd | Other services | 2016 |
| IPS Electec Ltd | Professional & scientific | 2012 |
| IRB Services Limited | Professional & scientific | 2019 |
| Iron Solutions Ltd | Wholesale & retail | 2013 |
| Ironstone Financial Ltd | Financial services | 2019 |
| Irowen Medical Ltd | Health & social care | 2022 |
| Isadora Ltd | Wholesale & retail | 2021 |
| Isha Trading Ltd | Wholesale & retail | 2025 |
| Isla Travel Consultancy Ltd | Administrative & support | 2024 |
| Island Van Centre Ltd | Wholesale & retail | 2025 |
| IT Solutions Today Limited | Information & communication | 2017 |
| IT Synergy Consultancy Ltd | Professional & scientific | 2014 |
| Itadent Worldwide Ltd | Information & communication | 2024 |
| Itech Glasgow Limited | Wholesale & retail | 2014 |
| Iter Consultancy Ltd | Information & communication | 2021 |
| Iter Interactive Ltd | Information & communication | 2025 |
| Ithica Film and Media Ltd | Information & communication | 2024 |
| ITO Electrical Ltd | Construction | 2024 |
| Itrade Crypto Limited | Extraterritorial | 2025 |
| Ivison Interiors Ltd | Construction | 2025 |
| Ivycroft Residents' Association Limited | Households | 1988 |
| J & E Business Services Ltd | Construction | 2022 |
| J & G Construction North East Limited | Construction | 2017 |
| J & J Willis Properties Ltd | Real estate | 2019 |
| J & M Network Limited | Financial services | 2016 |
| J & R Armitage Ltd | Manufacturing | 2019 |
| J & S Property Management North East Ltd | Real estate | 2023 |
| J Carter Construction Ltd | Manufacturing | 2021 |
| J Cartwright Construction Ltd | Administrative & support | 2021 |
| J Close Engineering Limited | Professional & scientific | 2024 |
| J Cosker Ltd | Construction | 2025 |
| J Costello Ltd | Extraterritorial | 2022 |
| J D Home Lettings Ltd | Real estate | 2021 |
| J DEV Estates Ltd | Real estate | 2020 |
| J Ferguson Investments Limited | Real estate | 2025 |
| J Ferguson Limited | Construction | 1972 |
| J G M Surveys Limited | Construction | 2010 |
| J G Vanek Limited | Health & social care | 2018 |
| J I Webb LLP | | 2023 |
| J L Kitchens Limited | Manufacturing | 2015 |
| J L Lannon Ltd | Information & communication | 2011 |
| J M Instruments Ltd | Construction | 2011 |
| J M Sorriso Limited | Hospitality | 2026 |
| J Manton Welding Ltd | Other services | 2018 |
| J Paul Belch Ltd | Information & communication | 2026 |