| I Denture & Hearing | Innisfil |
| I Denture & Hearing, Angus, Denture and Hearing Clinic, Angus | Essa |
| I Denture & Hearing, Innisfil, Denture and Hearing Clinic, Innisfil | Innisfil |
| IAVGO Community Legal Clinic | Toronto |
| IDA, Creemore Village Pharmacy | Clearview (Simcoe County) |
| IDA Pharmacy, Gravenhurst | Gravenhurst |
| IDA Pharmacy, Callander | Callander |
| IDA Pharmacy, Collingwood | Collingwood |
| IDA Pharmacy, Huntsville | Huntsville |
| IDA Pharmacy, Wasaga Beach | Wasaga Beach |
| Ideal Chiropractic | Barrie |
| Ideal Rebekah Lodge 199 | Midland |
| Iglesia Pentecostal LaSenda, Barrie | Barrie |
| Imani's Place Foundation | New Tecumseth |
| Immaculate Conception Roman Catholic Church, Stratford | Stratford |
| Immaculate Conception Roman Catholic Church, Alliston | New Tecumseth |
| In Search of Justice, Mailing Address | Vaughan |
| In Support Of Children Counselling, Unpublished, Counselling Services | |
| In the Bag Bulk Products, Listowel | Listowel |
| Income Security Advocacy Centre | Toronto |
| Income Tax Clinics | Northumberland County |
| Income Tax Clinics Peterborough | Peterborough (County of) |
| Income Tax Clinics, Perth County | Perth County |
| Independent Electricity System Operator, Mailing Address, saveONenergy Program | Ontario |
| Independent First Nations, Grey Bruce, Mobile Service, Jordan's Principle Navigator Program | Saugeen Shores |
| Independent Grocer Loblaws Pharmacy, Bracebridge, Independent Grocer Loblaw Pharmacy | Bracebridge |
| Independent Grocer Loblaws Pharmacy, Bracebridge, Christmas Dinner | Bracebridge |
| Independent Living Services Simcoe County | Barrie |
| Independent Living Services Simcoe County, Barrie, Accessibility, Resources and Connections | Barrie |
| Independent Living Services Simcoe County, Barrie, Assisted Living Services for Seniors | Barrie |
| Independent Living Services Simcoe County, Barrie, Attendant Care Services | Barrie |
| Independent Living Services Simcoe County, Barrie | Barrie |
| Independent Living Services Simcoe County, Online / Web Service, Quipit | Barrie |
| Independent Order of Odd Fellows, Exeter, Lodge 67 | Exeter |
| Independent Order of Odd Fellows, Stratford - The Grand Lodge of Ontario, Avon Lodge #41 | Stratford |
| Independent Order of Odd Fellows and Rebekah's, Cobourg | Cobourg |
| Independent Order of Odd Fellows Campbellford Lodge 248 | Trent Hills |
| Independent Suites (Orillia) | Orillia |
| Independent Taxi | Huntsville |
| Indian River Reptile Zoo | Peterborough (County of) |
| Indigenous Diabetes Health Circle, Central Region, Diabetes Wellness Program - Central Region | Barrie |
| Indigenous Diabetes Health Circle, Curve Lake | Curve Lake First Nation |
| Information and Privacy Commissioner of Ontario | Toronto Downtown |
| Information Orillia, Orillia Public Library, Income Tax Clinic | Orillia |
| Information Orillia, Orillia Public Library | Orillia |
| Inglenook Creche Childcare Centre | Owen Sound |
| Innisfil Community Church | Innisfil |
| Innisfil Community Church | Innisfil |
| Innisfil Community Church, Innisfil Food Bank | Innisfil |
| Innisfil Historical Society | Innisfil |
| Innisfil IdeaLAB & Library, Cookstown, Cookstown Branch | Cookstown |
| Innisfil Taxi | Innisfil |
| Innisfil. Fire and Rescue Service | Innisfil |
| Innisfil. Municipal Office | Innisfil |
| Innisfil. Municipal Office, Cookstown, Troy Scott Community Fridge | Innisfil |
| Innisfil. Municipal Office, Innisfil Recreation Centre, Troy Scott Community Fridge | Innisfil |
| Innisfil. Municipal Office, Lakeshore, Troy Scott Community Fridge | Innisfil |
| Innisfil. Municipal Office, Recreation Programs and Summer Day Camps, Town Hall | Innisfil |
| Innisfil. Municipal Office, Town Hall | Innisfil |
| Institute for Advancements in Mental Health | Toronto |
| Insurance Bureau of Canada, Ontario Head Office, Consumer Information Centre | Toronto |
| Integrated Autism Consulting, Barrie | Barrie |
| Intelligent Elders Club (The) | Orillia |
| Interfaith Northumberland | Cobourg |
| International Brotherhood of Electrical Workers, Barrie Office, Local 353 | Barrie |
| International Order of Alhambra, Grand Bend, Algarva 168 Caravan | Lambton Shores |
| International Pen Friends | Orillia |
| International Union of Operating Engineers, No Physical Address, Local 793 | Barrie |
| inTOUCH Hearing, Barrie | Barrie |
| Intyre Electronic Recycling | Huntsville |
| IODE, Festival Jubilee Chapter | Stratford |
| IODE- Maple Leaf Chapter, Goderich | Goderich |
| IOOF Seniors Homes | Barrie |
| IOOF Seniors Homes, Barrie - 10 Brooks St, Odd Fellow and Rebekah Home | Barrie |
| IOOF Seniors Homes, Barrie - 20 Brooks St, Heritage Place | Barrie |
| IOOF Seniors Homes, Barrie - 90, 92, 94 Dean Ave, The Terraces at Heritage Square | Barrie |
| IPIC Education and Counselling Services | Stratford |
| Irish Claddagh Club of Barrie and District | Barrie |
| It Takes a Village | North Perth |
| Itosu Kai Karate Collingwood | Collingwood |
| It's Personal Period | Chesley |
| iVolunteer Perth Huron, No Physical Address | Stratford |