Premier Kathleen Wynne will be at the facility, alongside Honda officials, to announce the news on Thursday morning.
The plants employ a total of 4,000 people and make Honda Civic and CR-V vehicles.The facilities currently have the capacity to make 390,000 cars a year, primarily for the Canadian and U.S. markets.
In a release issued earlier, the company said it had a "major announcement" to reveal at the plants, which are close to each other, and about 100 kilometres north and slightly west of Toronto.The funds will be used to invest in new technologies and processes that will make the facility what's known as a "lead plant" for Honda's popular Civic sedan.
"This marks the first time a Honda plant outside Japan has been designated as a ‘global lead plant’, which reflects the knowledge and experience of our Canadian associates," Honda Canada's president Jerry Chenkin said.
The province will chip in 10 per cent of the company's investment, which is $857 million.
Honda says the money brings the company's total investment in its Canadian operations to almost $4 billion since 1986, when the company became the first Japanese car company to set up shop in Canada.
Correction : A previous version of this story incorrectly reported that the Ontario government would be investing almost $900 million in the Honda plants. In fact, the company is investing $857 million, and the government is chipping in 10 per cent of that total.(Nov 06, 2014 9:57 AM)