| Hydroplan Properties Limited | Extraterritorial | 2013 |
| Hydrostem Ltd | Education | 2024 |
| Hyperion Hot Tubs Ltd | Wholesale & retail | 2020 |
| Hypnoboutique Ltd | Information & communication | 2019 |
| I R Stevens Ltd | Administrative & support | 2014 |
| I.L.F Services Ltd | Information & communication | 2020 |
| I.Z.M. Technologies Ltd | Information & communication | 2011 |
| I2R Designs Limited | Information & communication | 2022 |
| I99 Limited | Information & communication | 2019 |
| IAN and Michele Vincent Limited | Professional & scientific | 2024 |
| IAN M Louth Management Services Limited | Professional & scientific | 2014 |
| Ianderson Contracting Limited | Professional & scientific | 2023 |
| IC House Ltd | Financial services | 2026 |
| Icarus Transformation Limited | Information & communication | 2024 |
| ICE2O Consultancy Limited | Information & communication | 2016 |
| ICG Properties (Dorset) Limited | Real estate | 2015 |
| ICI2031 Limited | Professional & scientific | 2021 |
| Iconic Holdings Ltd | Manufacturing | 2023 |
| Icons and Outcasts Limited | Professional & scientific | 2002 |
| ICT Rated Ltd | Information & communication | 2014 |
| IDEA2IMPACT Ltd | Information & communication | 2026 |
| Ideal Financial Solutions Ltd | Professional & scientific | 2014 |
| Idevelop Advisory Ltd. | Other services | 2019 |
| IF Else Ltd | Information & communication | 2026 |
| Ifit Boilers Ltd | Construction | 2019 |
| IG Web Ltd | Information & communication | 2025 |
| Igen Media Ltd | Professional & scientific | 2022 |
| IGF Aerospace Consultants Limited | Professional & scientific | 2008 |
| Ignim Solutions Limited | Information & communication | 2006 |
| Igniteiq Ltd | Professional & scientific | 2025 |
| Iidnet Limited | Information & communication | 2015 |
| Iillu Limited | Real estate | 2021 |
| IJE Solutions Limited | Professional & scientific | 2023 |
| IJR Consulting Ltd | Professional & scientific | 2016 |
| Ikhba Consulting Limited | Professional & scientific | 2024 |
| IL Corno Family Limited | Hospitality | 2023 |
| IL Ghany Family Ltd | Extraterritorial | 2021 |
| Iladia Limited | Energy | 2019 |
| Ilmington Farm Limited | Agriculture & fishing | 2023 |
| IM Management Ltd | Professional & scientific | 2019 |
| Image Republic Limited | Administrative & support | 2006 |
| Image Stream Limited | Manufacturing | 2006 |
| Imageholders Ltd. | Wholesale & retail | 2002 |
| Imagicool Ltd | Construction | 2017 |
| Immaculate Block Services Ltd | Administrative & support | 2022 |
| Imogen Crawford Ltd | Professional & scientific | 2024 |
| Impala Consultancy Ltd | Information & communication | 2021 |
| Imperatrix Limited | Professional & scientific | 2024 |
| Imperfectly Normal CIC | Arts & recreation | 2025 |
| Imperial Leisure Vehicles Limited | Wholesale & retail | 2011 |
| Impress Sensors & Systems Limited | Manufacturing | 2002 |
| Impressprint Ltd | Manufacturing | 2018 |
| IN2 Group Limited | Wholesale & retail | 2014 |
| Increase Consulting Limited | Information & communication | 2022 |
| Indemandfba Ltd | Education | 2026 |
| Indemanduk Ltd | Wholesale & retail | 2022 |
| Independent Drainage Limited | Construction | 2004 |
| Independent Safety Evaluation Ltd | Professional & scientific | 2008 |
| Indiahaat 2012 Limited | Hospitality | 2019 |
| Indigo Design & Engineering Ltd | Professional & scientific | 2012 |
| Indigo HR Tech Ltd | Information & communication | 2024 |
| Indigo Point Limited | Information & communication | 2010 |
| Industrial Interface Limited | Manufacturing | 2005 |
| Industrial Suppliers (Wimborne) Limited | Wholesale & retail | 1954 |
| Infinite Analysis Limited | Professional & scientific | 2018 |
| Infinite Possibilities Consulting Limited | Information & communication | 2025 |
| Infinity Tutors Ltd | Education | 2025 |
| Informatics Professionals Ltd | Professional & scientific | 2016 |
| Infosec Solutions Limited | Information & communication | 2015 |
| Infotech Sourcing Ltd | Professional & scientific | 2023 |
| Infotel Limited | Information & communication | 2009 |
| Infrabee Ltd. | Professional & scientific | 2012 |
| Infranexa Solutions Ltd | Information & communication | 2007 |
| Ingenix Limited | Professional & scientific | 2025 |
| Ingentys Limited | Professional & scientific | 2020 |
| Initio Learning Trust | Education | 2014 |
| Initium Novum Solutions Limited | Professional & scientific | 2017 |
| Inkblot Limited | Professional & scientific | 2008 |
| Innovate Dorset Ltd | Health & social care | 2013 |
| Innovatech Services Ltd | Information & communication | 2023 |
| Innovation Engineering Services Limited | Information & communication | 2023 |
| Innovative Business Consultancy Ltd | Administrative & support | 2021 |
| Innovent Labs Limited | Information & communication | 2023 |
| Innpacked Limited | Professional & scientific | 2003 |
| Innvotec 5 Limited Liability Partnership | | 2004 |
| Inoplas Technology Limited | Manufacturing | 1973 |
| Inquisitive PIG Limited | Information & communication | 2021 |
| Insight Security Specialists Ltd | Extraterritorial | 2013 |
| Insilico Consulting Limited | Information & communication | 2021 |
| Inspire Career Consultancy Limited | Education | 2002 |
| Inspire Home Automation Limited | Manufacturing | 2012 |
| Inspire Property Solutions Ltd | Real estate | 2019 |
| Inspired Consulting Services Limited | Information & communication | 2018 |
| Instandart Ltd | Information & communication | 2022 |
| Instig@Te Ltd | Information & communication | 2000 |
| Integral Development Partners Limited | Professional & scientific | 2024 |
| Integral Heating and Plumbing Limited | Construction | 2025 |
| Integral Refurbishments & Maintenance Limited | Other services | 2020 |
| Integrum Associates Ltd | Information & communication | 2024 |
| Intelligent MTG Ltd | Financial services | 2016 |