| Humilis Sapientia Ltd | Administrative & support | 2015 |
| Hummingbird Human Resources Ltd | Administrative & support | 2012 |
| Hunt Dermatology Limited | Health & social care | 2022 |
| Hunter and Hughes Ltd | Professional & scientific | 2021 |
| Hunter Banks Ltd | Construction | 2026 |
| Hunter Stone (UK) Limited | Professional & scientific | 2008 |
| Huntstown Properties Ltd | Construction | 2024 |
| Hurrell Holdings Limited | Financial services | 2023 |
| Hurriback Limited | Transport & logistics | 2021 |
| Hurricaneco Ltd | Wholesale & retail | 2026 |
| Hurstibs Investments Limited | Real estate | 1960 |
| Hustle Hair Ltd | Other services | 2021 |
| HY Fiachra Energy Ltd | Energy | 2013 |
| Hybrid Electrics Motor Company Ltd | Wholesale & retail | 2019 |
| Hybrid Generation Ltd | Other services | 2025 |
| Hybrid Heat Ltd | Construction | 2017 |
| Hybrid IT Consulting Ltd | Information & communication | 2013 |
| Hybrid Touch Games Limited | Information & communication | 2013 |
| Hyde Park Cars (Plymouth) Limited | Wholesale & retail | 1999 |
| Hyde Park Flats Management Ltd | Real estate | 2013 |
| Hydraplus Ltd | Other services | 2025 |
| Hydrastorm Technologies Ltd | Manufacturing | 2025 |
| Hydro Environmental Limited | Construction | 1996 |
| Hydro Health Ltd | Wholesale & retail | 2020 |
| Hygeia Property Services Ltd | Administrative & support | 2023 |
| Hymec Aerospace (UK) Limited | Administrative & support | 1999 |
| Hymec Holdings US Limited | Financial services | 2021 |
| Hymec Investments Holdings Limited | Financial services | 2023 |
| Hymec Investments Ltd | Construction | 2015 |
| Hymec Precision Engineering Limited | Administrative & support | 2018 |
| Hymec Properties and Leasing Limited | Real estate | 2019 |
| Hymec Property Holdings Limited | Financial services | 2023 |
| Hyperx Capital Ltd | Wholesale & retail | 2025 |
| Hywell Evans Ltd | Construction | 2017 |
| I & S Commercial Vehicle Repairs Ltd | Wholesale & retail | 2013 |
| I M Therapy Ltd | Health & social care | 2017 |
| I Mckenna Ltd | Real estate | 2025 |
| I Need a Hand Ltd | Wholesale & retail | 2019 |
| I&H Services Limited | Administrative & support | 2023 |
| I-Grow Care and Support Limited | Health & social care | 2011 |
| I-Qapp Limited | Information & communication | 2019 |
| I. Rangeley & Company Limited | Real estate | 1973 |
| I.D. Civils and Utilities Ltd | Construction | 2018 |
| IA Group Holdings Limited | Wholesale & retail | 2017 |
| Iadvice Global Immigration Services Limited | Professional & scientific | 2021 |
| IAN M Sumner Installation Ltd | Construction | 2020 |
| IAN Wadland Roofing Ltd | Construction | 2020 |
| IAN Webb Specialist Cars Ltd | Wholesale & retail | 2013 |
| IB Surveying Ltd | Professional & scientific | 2026 |
| Ibuild (SW) Ltd | Construction | 2019 |
| IBV Service Maintenance and Logistic Ltd | Construction | 2013 |
| Icanok Limited | Professional & scientific | 2007 |
| ICC Integrated Consumer Consultants Limited | Construction | 2006 |
| Ice Consulting & Design Ltd | Professional & scientific | 2022 |
| Iceni KK Limited | Wholesale & retail | 2011 |
| Ickon Limited | Professional & scientific | 2016 |
| Iconic Eyewear Limited | Wholesale & retail | 2015 |
| Iconic Eyewear Plymstock Ltd | Wholesale & retail | 2020 |
| ICT Studio Limited | Information & communication | 2014 |
| ID Fashion Ltd | Wholesale & retail | 2015 |
| Ideal Barbers Plymouth Limited | Other services | 2021 |
| Ideal Interactive Group Ltd | Professional & scientific | 2019 |
| Ideal Technology Limited | Information & communication | 1996 |
| Identify Design Limited | Arts & recreation | 2013 |
| Idooh Designs Ltd | Manufacturing | 2021 |
| Idris Foods (SW) Ltd | Hospitality | 2026 |
| Idship Limited | Transport & logistics | 2023 |
| Ielts Kapow Ltd | Education | 2025 |
| Iepd Limited | Health & social care | 2020 |
| Ignite Heating Services Ltd | Construction | 2023 |
| Ihde Limited | Hospitality | 2020 |
| IIA Lotus Flower Counseling Ltd | Professional & scientific | 2020 |
| IJI Property Ventures Ltd | Real estate | 2026 |
| IJM Developments Ltd | Construction | 2023 |
| IJM Kitchens and Bathrooms Ltd | Construction | 2022 |
| IJR Building and Maintenance Ltd | Construction | 2026 |
| Ikey Ltd | Real estate | 2020 |
| Ikhuoria Enterprise Ltd | Transport & logistics | 2022 |
| Ikkr Ltd | Households | 2024 |
| Ikunix Ltd | Information & communication | 2023 |
| Illicit Production Limited | Information & communication | 2011 |
| Imagery Limited | Wholesale & retail | 2005 |
| Imagine Office Supplies Limited | Wholesale & retail | 2011 |
| Imattination Limited | Professional & scientific | 2013 |
| Imcorp Ltd | Professional & scientific | 2017 |
| IMJ Edmunds Limited | Construction | 2005 |
| IMJ Software Limited | Information & communication | 2012 |
| Immortal Yogi Ltd | Wholesale & retail | 2024 |
| Imo-Geo Ltd | Professional & scientific | 2019 |
| Imperial Car Centre (SW) Ltd | Wholesale & retail | 2020 |
| Imperial Holdings (SW) Limited | Professional & scientific | 2022 |
| Imperial Roofing and Building Contractors Ltd | Construction | 2025 |
| Imprimere Ltd | Manufacturing | 2025 |
| Improve My Health Ltd | Health & social care | 2025 |
| Improving Lives Plymouth | Health & social care | 1991 |
| IN My TUM Ltd | Extraterritorial | 2016 |
| IN Seoul Ltd | Hospitality | 2024 |
| IN Vitro Productions Ltd | Arts & recreation | 2026 |
| In-Informatics Ltd | Manufacturing | 2020 |
| IN2MINDZ Limited | Arts & recreation | 2019 |