| Indoor Fireworks Ltd | Financial services | 2014 |
| Industrial Powder and Paint Services Limited | Wholesale & retail | 1990 |
| Ineffable Ltd | Health & social care | 2026 |
| Infant Collective Ltd | Wholesale & retail | 2023 |
| Infiniti Cloud Solutions Limited | Information & communication | 2014 |
| Infinity & Logistics Ltd | Transport & logistics | 2025 |
| Infinity Cleaning Services Ltd | Administrative & support | 2020 |
| Infinity Tech Systems Ltd | Information & communication | 2021 |
| Infinity Wheelz Ltd | Professional & scientific | 2025 |
| Infire Investments Limited | Other services | 2009 |
| Infirmity Care Limited | Wholesale & retail | 2017 |
| Inflatable Structures Limited | Wholesale & retail | 2016 |
| Inflow Partnership Limited | Administrative & support | 2021 |
| Info First Call Limited | Administrative & support | 2025 |
| Infoport Ltd | Administrative & support | 2022 |
| Inform Products Ltd | Manufacturing | 1937 |
| Information Technology Systems (UK) Limited | Information & communication | 2013 |
| Informed Strategy Ltd | Information & communication | 2016 |
| Informer Limited | Real estate | 1981 |
| Infotex UK Limited | Information & communication | 1998 |
| Infotex.Io Ltd | Information & communication | 2020 |
| Infranor Limited | Wholesale & retail | 1982 |
| Infrasol Ltd | Construction | 2026 |
| ING Building Ltd | Construction | 2013 |
| Ingenium Classics Ltd | Wholesale & retail | 2019 |
| Ingest Media Ltd | Information & communication | 2016 |
| Ingoldsby Limited | Real estate | 1988 |
| Ingot Aviation Services Limited | Transport & logistics | 2020 |
| Ingot Ventilation Services Limited | Administrative & support | 2003 |
| Ingram Windows & Doors Limited | Construction | 2013 |
| Inishmeane Limited | Wholesale & retail | 2021 |
| Initiated Nation Ltd | Arts & recreation | 2018 |
| Inky and the Bears Ltd | Arts & recreation | 2023 |
| Inman & Co (Consultants) Limited | Information & communication | 2005 |
| Inmelius Limited | Professional & scientific | 2026 |
| Inn Stable Limited | Hospitality | 2020 |
| Innbizico Ltd | Transport & logistics | 2024 |
| Innergrove Wellness Ltd | Extraterritorial | 2026 |
| Innerspace Associates Limited | Administrative & support | 2001 |
| INNOV842 Ltd | Administrative & support | 2019 |
| Innovate (H & S C) Services Limited | Health & social care | 2019 |
| Innovate ADS Ltd | Professional & scientific | 2023 |
| Innovate IQ Properties Limited | Real estate | 2025 |
| Innovation Martlesham Limited | Administrative & support | 2014 |
| Innovative Edge Ltd | Professional & scientific | 2024 |
| Innoventuscore Ltd | Information & communication | 2025 |
| Innovis Digital Ltd | Information & communication | 2025 |
| Inns of Distinction Limited | Hospitality | 2002 |
| Innuendo Vapes Ltd | Manufacturing | 2021 |
| INOV8 Developments Ltd | Real estate | 2024 |
| INOV8 Holdings Limited | Construction | 2022 |
| Input Investments Ltd | Financial services | 2020 |
| Inside OUT Education Limited | Education | 2014 |
| Inside Right Limited | Administrative & support | 2015 |
| Insieme Group Ltd | Administrative & support | 2023 |
| Insight Business Systems Limited | Information & communication | 1996 |
| Insight Energy Optimisation Limited | Professional & scientific | 2024 |
| Insight Energy Renewables Limited | Construction | 2021 |
| Insight Equity Limited | Administrative & support | 2020 |
| Insight Residential (Suffolk) Ltd | Real estate | 2026 |
| INSIGHT2 Mental Health Limited | Administrative & support | 2020 |
| Insound Limited | Wholesale & retail | 2004 |
| Insperonq Limited | Wholesale & retail | 2018 |
| Inspire Counselling and Training Limited | Health & social care | 1998 |
| Inspire Drive Grow Limited | Professional & scientific | 2024 |
| Inspire Pro Trading Ltd | Transport & logistics | 2022 |
| Inspire Suffolk Ltd | Education | 2003 |
| Inspired EAR Care Limited | Health & social care | 2018 |
| Inspired Foot Care Limited | Health & social care | 2017 |
| Inspiring Aspirations Plus Ltd | Education | 2020 |
| Installeros Ltd | Information & communication | 2026 |
| Insurance & Reinsurance Legacy Association Limited | Wholesale & retail | 2005 |
| Intec Future Solutions Ltd | Water & waste | 2020 |
| Intechom Ltd | Manufacturing | 2025 |
| Integra Metering UK Limited | Professional & scientific | 2023 |
| Integral Outsource Ltd | Administrative & support | 2023 |
| Integrasol Ventures LLP | | 2025 |
| Integrated Glazing Limited | Construction | 2022 |
| Integrity Assess Solutions Ltd | Professional & scientific | 2024 |
| Intelligent Storage Ltd | Manufacturing | 2002 |
| Intelliinventions Ltd | Information & communication | 2013 |
| Interact Structural Fire Protection Limited | Manufacturing | 2016 |
| Interdomain Ltd | Information & communication | 2022 |
| Interfreight (UK) Limited | Transport & logistics | 2007 |
| Interim Automotive Limited | Professional & scientific | 2013 |
| Interminerva Ltd | Extraterritorial | 2024 |
| International Butchers Ltd | Wholesale & retail | 2020 |
| International College for Exercise Professionals Limited | Education | 2021 |
| International Executive Function Coaching Certification CIC | Education | 2025 |
| International Food Store Ltd | Wholesale & retail | 2016 |
| International Fulfillment Services Ltd | Professional & scientific | 2018 |
| International Games Jobs Ltd | Information & communication | 2019 |
| International V Service Limited | Professional & scientific | 2015 |
| Interplanetary Enterprises Ltd | Arts & recreation | 2021 |
| Intershore Web Development Ltd | Information & communication | 2009 |
| Intertrading Holding Limited | Information & communication | 2025 |
| Interyacht Limited | Extraterritorial | 1948 |
| Inti's Bounty Limited | Wholesale & retail | 2016 |
| Into IT Solutions Limited | Construction | 2023 |
| Intyre Home Design Limited | Construction | 2004 |