Madi Vanstone, 12, of Beeton, Ont., suffers from a rare genetic variant of cystic fibrosis.
She has been taking Kalydeco, a drug which was not being covered by the province, even though it costs hundreds of thousands of dollars for a year’s supply.
Vanstone and her family had been lobbying the government on the issue.
On Tuesday, her mother received a call from the health minister.
"I have been assured by Deb Matthews that Ontario is going to fund it, so she told me that within weeks that this drug will be in the hands of all the people that need it," Beth Vanstone told CBC News in a telephone interview.
Madi said it feels "so great" to have got what she needed and to have been able to help others in the same position.
The news comes days after the Pan-Canadian Pricing Alliance and the drug’s manufacturer reached a tentative deal on Kalydeco.
There is still some paperwork to do before it can be approved, but the Ministry of Health and Long Term Care says it will bring the drug into the publicly funded program as soon as possible.