| Immersive Holdings Ltd | Financial services | 2024 |
| Immersive Rights Ltd | Financial services | 2024 |
| Immune Insight Limited | Professional & scientific | 2016 |
| Impact Brands Trading Company Ltd | Wholesale & retail | 1994 |
| Impact Gardens and Driveways Limited | Administrative & support | 2022 |
| Impact the Future Ltd | Professional & scientific | 2014 |
| Impactivity (UK) Ltd | Professional & scientific | 2013 |
| Imperium Capital Holdings Ltd | Financial services | 2025 |
| Imperium Law Solicitors Limited | Professional & scientific | 2011 |
| Importers Direct Ltd | Wholesale & retail | 2022 |
| Imprescape Ltd | Construction | 2019 |
| Impression Production Limited | Administrative & support | 2010 |
| IN Touch With Bricks Limited | Wholesale & retail | 1990 |
| IN Touch With Property Ltd | Real estate | 2023 |
| IN2FITINTERIORS Ltd | Construction | 2025 |
| Inc (RN) Ltd | Hospitality | 2013 |
| Incubation Arts Ltd | Arts & recreation | 2012 |
| Independent Valuation Services Limited | Wholesale & retail | 2015 |
| Indian Thali Ltd | Hospitality | 2022 |
| Indigo Flavours Limited | Hospitality | 2024 |
| Individual Financial Services Limited | Financial services | 2013 |
| Indulge Macc Ltd | Hospitality | 2019 |
| Industrial Stocktake Limited | Professional & scientific | 2000 |
| Industrilas Ltd | Extraterritorial | 2009 |
| Inevolution Ltd | Real estate | 2022 |
| Infex Therapeutics Limited | Professional & scientific | 2016 |
| Influenz Ltd | Information & communication | 2025 |
| Inform PR & Communications Limited | Professional & scientific | 2010 |
| Inform Strategic Communications Limited | Professional & scientific | 2019 |
| Infront Homes Limited | Construction | 2011 |
| Ingenious Laboratories Limited | Health & social care | 2014 |
| Ingham & Borough Limited | Administrative & support | 2022 |
| Inglewood Engineering Consultancy Limited | Professional & scientific | 1983 |
| Inhale Consulting Ltd | Professional & scientific | 2011 |
| Iniya Property Investments Limited | Real estate | 2025 |
| Inkpower Limited | | 1993 |
| Inland Voyages (Bookings) Limited | Administrative & support | 1976 |
| Inland Voyages Limited | Administrative & support | 1976 |
| INNOV8ASSET Limited | Construction | 2020 |
| Innovative Hospitality Consultancy Ltd | Professional & scientific | 2025 |
| Innstone Healthcare Limited | Financial services | 2022 |
| Inorda Ltd | Professional & scientific | 2025 |
| Inputt Golf Limited | Wholesale & retail | 2008 |
| INS Technologies Limited | Information & communication | 2023 |
| Inside and OUT Property Maintenance Ltd | Administrative & support | 2012 |
| Insight Consulting Management Limited | Administrative & support | 2017 |
| Insightful Communications Limited | Professional & scientific | 2020 |
| Insilicolynx Limited | Professional & scientific | 2015 |
| Inspire Films Ltd | Information & communication | 2025 |
| Inspired by Isherwood Limited | Administrative & support | 2019 |
| Instance Global Technology Limited | Professional & scientific | 2019 |
| Instance Global UK Limited | Information & communication | 2016 |
| Instil BIO (UK) Limited | Professional & scientific | 2008 |
| Intaguard Security Limited | Administrative & support | 2020 |
| Integral BIO Partner LLP | | 2016 |
| Integral Kitchens Ltd | Wholesale & retail | 2014 |
| Intelligence & Investigation Services Ltd | Administrative & support | 1997 |
| Intelligent Billing Limited | Extraterritorial | 2008 |
| Intelligent OD Ltd | Professional & scientific | 2022 |
| Intelligent Pricing (UK) Ltd | Information & communication | 2025 |
| Intention Action Result Ltd | Information & communication | 2022 |
| Inter-Est Systems Limited | Professional & scientific | 2012 |
| Inter-Est Technology Group Ltd | Professional & scientific | 2003 |
| Inter-Est UK Limited | Information & communication | 2003 |
| Inter-Pares Associates Limited | Professional & scientific | 2007 |
| Interfit Furniture Components Limited | Wholesale & retail | 2019 |
| Interiors by Ingrid Ltd | Professional & scientific | 2017 |
| International Basketball Academy Ltd | Education | 2025 |
| International Business Development Ltd | Professional & scientific | 2013 |
| Intersafety (Industrial Protection) Limited | Wholesale & retail | 2002 |
| Inverness Danceworks CIC | Arts & recreation | 2021 |
| Ioniq NZ Limited | Wholesale & retail | 2026 |
| IOT Hub Limited | Administrative & support | 2014 |
| IPB Properties Limited | Real estate | 2013 |
| Iphorms Ltd | Administrative & support | 2019 |
| Iridium Cloud Limited | Information & communication | 2016 |
| Irim Ltd | Professional & scientific | 2015 |
| IRM Installations Limited | Construction | 2020 |
| Iron Grips Limited | Information & communication | 2024 |
| Irwin Consultants Limited | Professional & scientific | 2019 |
| Isaac Massey Limited | Administrative & support | 2013 |
| Ishaal Ltd | Transport & logistics | 2019 |
| IT Bitz Ltd | Wholesale & retail | 2021 |
| Itconstruct Projects Ltd | Construction | 2011 |
| IV Consulting Services Limited | Information & communication | 2021 |
| IVY Associates Limited | Real estate | 2011 |
| Iwona's Tailoring Studio Ltd | Other services | 2025 |
| J & H Plumbing and Heating Limited | Construction | 2010 |
| J & L Howe Property Refurbishment Ltd | Construction | 2022 |
| J & L Lock & Key Services Limited | Administrative & support | 2014 |
| J + P M Makinson + Sons | | 1997 |
| J a Automotive Ltd | Professional & scientific | 2018 |
| J a Hyde Ltd | Construction | 2019 |
| J a Rose Limited | Wholesale & retail | 2009 |
| J Carver E&I Limited | Professional & scientific | 2007 |
| J D S Admin Services Limited | Administrative & support | 2009 |
| J Davidson Builders Ltd | Construction | 2023 |
| J Davidson Property Ltd | Construction | 2024 |
| J Drabble & SON Limited | Construction | 2023 |
| J Flower Electrical Limited | Construction | 2020 |