| Impulse Energy Ltd | Administrative & support | 2015 |
| Impulse Marketing Ltd | Administrative & support | 2022 |
| Impulse Properties & Developments Ltd | Real estate | 2023 |
| IMS Maintenance Ltd | Construction | 2014 |
| IMS People (UK) Limited | Professional & scientific | 2024 |
| IN House Contracts Limited | Construction | 2025 |
| IN House Contracts Management Limited | Real estate | 2026 |
| IN the EYE Marketing Ltd | Professional & scientific | 2009 |
| Inca Properties Ltd. | Real estate | 1998 |
| Inca Property Holdings Limited | Financial services | 2014 |
| Incanunez Ltd | Wholesale & retail | 2014 |
| Ince Building & Carpentry Ltd | Construction | 2021 |
| Incorporated Systems Limited | Construction | 2006 |
| Incre Solutions Limited | Financial services | 2015 |
| Incredible Works Ltd | Information & communication | 2026 |
| Incrops Ltd | Agriculture & fishing | 2024 |
| Incubate & Innovate Limited | Professional & scientific | 2024 |
| Indalohe Ltd | Professional & scientific | 2026 |
| Indasa Abrasives (UK) Ltd | Wholesale & retail | 1989 |
| Inde Operations Ltd | Construction | 2007 |
| Independent Copier Solutions Limited | Manufacturing | 2017 |
| Independent Financial Success Limited | Extraterritorial | 2009 |
| Independent London Market Services Limited | Financial services | 2000 |
| Independent Risk Management Solutions Limited | Financial services | 2013 |
| Independent Services Group Limited | Professional & scientific | 2001 |
| Indian Village Colchester Limited | Hospitality | 2025 |
| Indiglo Group Limited | Professional & scientific | 2018 |
| Indigo Energy Ltd | Construction | 2022 |
| Indigo Internet Limited | Information & communication | 2020 |
| Indigo Star Ltd | Construction | 2018 |
| Industrial Doors East Anglia Ltd | Construction | 2025 |
| Industrial Electrical Services (I.E.S.) Limited | Manufacturing | 1988 |
| Industry Unlimited Ltd | Professional & scientific | 2022 |
| Inex Carpentry and Building Services Ltd | Construction | 2025 |
| Infinite Energy Design Ltd | Professional & scientific | 2023 |
| Infinite Energy Solutions UK Ltd | Wholesale & retail | 2022 |
| Infinite Hills Estate Limited | Real estate | 2024 |
| Infinite Rainbow Ltd | Wholesale & retail | 2022 |
| Infinity Benevolence Concepts Ltd | Other services | 2024 |
| Infinity IT & Marketing Ltd | Information & communication | 2026 |
| Infinity Online Ltd | Information & communication | 1999 |
| Infinity Property & Financial Solutions Ltd | Professional & scientific | 2018 |
| Infinityx Group Limited | Wholesale & retail | 2018 |
| Inflata MAN UK Limited | Professional & scientific | 2023 |
| Info Consulting Services Ltd | Information & communication | 2010 |
| Infocapture Limited | Information & communication | 2007 |
| Inform Performance & Development Ltd | Health & social care | 2025 |
| Information Asset Management Solutions Ltd | Professional & scientific | 2016 |
| Infoviz Ltd | Information & communication | 2015 |
| Infra-V Ltd | Information & communication | 2010 |
| Infyniq Agro Ltd | Wholesale & retail | 2026 |
| Infyniq Limited | Information & communication | 2025 |
| Ingadent Ltd | Health & social care | 2026 |
| Ingeni Limited | Professional & scientific | 2015 |
| Ingeni Partners Limited | Administrative & support | 2004 |
| Ingeni Services Group Limited | Financial services | 2002 |
| Ingeni Services Limited | Financial services | 2009 |
| Inglorious Dragons Ltd | Wholesale & retail | 2023 |
| Inglorious Motorcycles Ltd | Manufacturing | 2023 |
| Ingram Inc Limited | Information & communication | 2017 |
| Init Together Ltd | Information & communication | 2010 |
| Injury Workshop Ltd | Other services | 2020 |
| INK House Trading Limited | Wholesale & retail | 2017 |
| INK Jungle Limited | Administrative & support | 2012 |
| Inkind Media Ltd | Information & communication | 2026 |
| Inkpen Downie Architecture & Design Limited | Professional & scientific | 2006 |
| Inline Training Ltd | Professional & scientific | 2018 |
| Inlustris Gifts Ltd | Wholesale & retail | 2021 |
| Inn-House Technology Limited | Manufacturing | 1991 |
| Inner Hope CIC | Health & social care | 2024 |
| Innocaptiva Limited | Information & communication | 2024 |
| INNOV8 Electrical Solutions Ltd | Construction | 2020 |
| INNOV8TEK Limited | Information & communication | 2024 |
| Innovant Systems Ltd | Information & communication | 2023 |
| Innovate Plus Technology Limited | Information & communication | 2022 |
| Innovate Security Ltd | Administrative & support | 2009 |
| Innovate Tech Consultancy Ltd | Information & communication | 2023 |
| Innovative Online Solutions Limited | Real estate | 2020 |
| Innovative Transformations Limited | Information & communication | 2012 |
| Innoven Ltd | Professional & scientific | 2019 |
| Innovex Solutions Limited | Professional & scientific | 2018 |
| Innovix Law Ltd | Professional & scientific | 2019 |
| Inntel Events Limited | Administrative & support | 2007 |
| Inntel Group Limited | Administrative & support | 2011 |
| Inova (UK) Ltd | Construction | 1998 |
| Inova Ltd | Extraterritorial | 2021 |
| Inparsiddy Development Society | Health & social care | 2017 |
| Inprint (Colchester) Limited | Wholesale & retail | 2012 |
| INR Services Limited | Health & social care | 2025 |
| Inrenovate Ltd | Construction | 2016 |
| Insatiable Lashes Ltd | Wholesale & retail | 2017 |
| Inside Avenue Recruitment Ltd | Administrative & support | 2015 |
| Insidetext Ltd | Information & communication | 2021 |
| Insight by ES Limited | Professional & scientific | 2024 |
| Inspec Offshore Ltd | Administrative & support | 2016 |
| Inspectorate International Limited | Professional & scientific | 1959 |
| Inspinity Unlimited | Real estate | 2022 |
| Inspire Haircare Ltd | Other services | 2013 |
| Inspired & Eclectic Limited | Information & communication | 2008 |
| Inspired Futures Limited | Administrative & support | 2006 |