| Innovate Community Care Group Ltd | Solihull | 2025 |
| Innovation for Agriculture | Kenilworth | 2013 |
| Innovations (Home Counties) CIC | Milton Keynes | 2020 |
| Innovative Care & Digital Skills CIC | Romford | 2025 |
| Inntabiz Limited | Melton Mowbray | 2008 |
| Inovation by RBT Ltd | Hornchurch | 2025 |
| Inra Healthcare Ltd | London | 2021 |
| Insight Workplace Safety Ltd | Newport | 2018 |
| Insightful Mind Community Interest Company | London | 2023 |
| Insignia Fire Protection Services Ltd | Southend-On-Sea | 2024 |
| Insignia Global Group Ltd | Kettering | 2025 |
| Insignia Secure Solutions (UK) Limited | London | 2019 |
| Inspira Health Care Ltd | Liverpool | 2023 |
| Inspiration 20 Limited | London | 2020 |
| Inspire 2 Train Limited | Willenhall | 2022 |
| Inspire and Create Limited | Wembley | 2021 |
| Inspire Children Services Ltd | Clevedon | 2023 |
| Inspire Community Advice Service CIC | Birmingham | 2020 |
| Inspire Crypto Limited | Scarborough | 2022 |
| Inspire Independence Ltd | Sheffield | 2025 |
| Inspire Medical Ltd | Southall | 2021 |
| Inspire to Outstand Ltd | Northwich | 2019 |
| Inspired Health Care Services Ltd | Thame | 2025 |
| Institute of Islamic Strategic & Socio-Political Affairs | Maidstone | 2012 |
| Integra Resourcing Group Ltd | Chester | 2026 |
| Integral Care Ltd | London | 2020 |
| Integral Fire Management Ltd | Sevenoaks | 2023 |
| Integral Fire Safety UK Ltd | Shifnal | 2002 |
| Integral Fire Solutions Limited | Burntwood | 2025 |
| Integral Fire Sprinklers Ltd | Merthyr Tydfil | 2017 |
| Integral Health Star Method Limited | Manchester | 2021 |
| Integrated Care Solutions (East Kent) Holdings Limited | Nottingham | 2003 |
| Integrated Care Solutions (Shropshire) Holdings Limited | Nottingham | 2005 |
| Integrated Care Solutions (Shropshire) Limited | Nottingham | 2005 |
| Integrated Diaspora Services (UK) Limited | Birmingham | 2022 |
| Integrated Fire and Security Solutions Limited | Henfield | 2017 |
| Integrated Fire Ltd | London | 2022 |
| Integrated Global Menospace Solutions CIC | London | 2025 |
| Integrity Community Care Ltd | Ryton | 2024 |
| Integrity Fire Protection Ltd | Liverpool | 2023 |
| Integrity Healthcare Solutions Ltd | London | 2021 |
| Integrous Limited | London | 2023 |
| Inteli Fire & Security Solutions Ltd. | Strathaven | 2012 |
| Intell Consulting Services Ltd | London | 2023 |
| Intellectus Group Ltd | Guildford | 2019 |
| Intellitech Services Limited | Boston | 2017 |
| Intense Fire Ltd | London | 2026 |
| Intent Care Services Limited | Croydon | 2020 |
| Inter-Leadco Ltd | Cambridge | 2025 |
| Intercept Fire and Security Limited | Watford | 2015 |
| Intercept Fire Safety Limited | Westerham | 2023 |
| Interexpansion Ltd | Epsom | 2025 |
| Interface Enterprises Limited | Norwich | 2012 |
| Interlinked Services Limited | London | 2025 |
| Internal Fire Solutions Limited | Slough | 2024 |
| International Arbitration Centre Limited | London | 2018 |
| International Beauty & Aesthetics Limited | Worksop | 2025 |
| International Beauty Training Ltd | Retford | 2021 |
| International Buddhist Progress Society (Manchester) Limited | Manchester | 2001 |
| International Curriculum and Assessment Network Ltd | London | 2018 |
| International Education and Development Center Ltd | London | 2025 |
| International Fire Installations Ltd | Bracknell | 2025 |
| International Justice Organization in London Ltd | Cardiff | 2025 |
| International Link Limited | Bristol | 2025 |
| International Military Sales Limited | Camberley | 1990 |
| International Reclaim Committee Limited | London | 2024 |
| International Society of Reproductive Surgery and Fallopian Tube (Isrsft) CIC | London | 2025 |
| Interpol Federal | London | 2022 |
| Interventions Alliance Ltd | Gravesend | 2024 |
| Intu Fire Compliance Ltd | Rugby | 2026 |
| Intumescent Fire Protection Ltd | Ongar | 2023 |
| Inveris Training Solutions Limited | Ashford | 1992 |
| Inverness Badenoch and Strathspey Citizens Advice Bureau | Inverness | 1992 |
| Invested Partnering Limited | Havant | 2022 |
| Invictus Complex Care Ltd | Southampton | 2020 |
| Invictus Fire Safety Ltd | Cambridge | 2018 |
| Involution Consulting Ltd | Barking | 2021 |
| Inzpire Limited | Lincoln | 2005 |
| IOL Safety Support Ltd | Liverpool | 2024 |
| IP Fire Protection Ltd | Cheshunt | 2011 |
| IPI Homes Vantor Ltd. | Ipswich | 2025 |
| Ipsotek Limited | London | 2001 |
| Iqualifi Ltd | Bovey Tracey | 2020 |
| Iram Ikram Ltd | Halifax | 2021 |
| Irara Secure Solutions Limited | Sherborne | 2025 |
| Irara Services Limited | Sherborne | 2017 |
| Iris Health and Well-Being Limited | St. Helens | 2023 |
| Ironclad Safety Solutions Ltd | London | 2024 |
| IRS Worldwide Limited | Buckingham | 2020 |
| Isaac .N. Healthcare Services Ltd | Cardiff | 2018 |
| Isca Fire and Safety Limited | Exeter | 2019 |
| ISE Fire Products & Services Limited | Little Harrowden | 1999 |
| Isha Healthcare Limited | Chigwell | 2024 |
| Ishmoney Enterprises Limited | Luton | 2020 |
| ISI92 Limited | Harrow | 2021 |
| Isla MAE Ltd | Sittingbourne | 2024 |
| Island Fire Doors Ltd | Anglesey | 2024 |
| Islington Ltd | London | 2004 |
| Isofire Ltd | South Shields | 2023 |
| Isogun Limited | London | 2022 |