Serenity Rossi was last seen at home around 12:15 p.m. in the Jane Street and Grandravine Drive area in northern Toronto.
Police say they are concerned for her safety, especially given her young age.
Officials from 31 Division say she left home upset with her family.
Rossi is described as 5'3, with long dark brown hair worn in a ponytail. She was last spotted wearing black skinny jeans and a blue hoodie with white strings. Police also say she was carrying a green plaid backpack.
Anyone with information is asked to contact police at 416-808-3100 or anonymously via Crime Stoppers.