Wynne had previously rebuffed calls for an apology, saying only that she regretted the cost of cancelling the plants, which was more than double what the governing Liberals had claimed.
But she finally apologized on TV Ontario's The Agenda, saying she was "very sorry" for the mistakes the government made.
In fact, the premier said she was sorry 11 times during her interview with host Steve Paikin.
"The people of Ontario need to hear that I'm sorry because I am, I am sorry," she said.
"I'm sorry that we didn't have a better process up front. I'm sorry that we didn't site those gas plants better and that's why a new protocol needs to be in place."
Wynne's apology came after both she and her predecessor Dalton McGuinty testified at a committee looking into the cancelled gas plants.
McGuinty said he made the political decisions to cancel the plants in Oakville and Mississauga, but had no idea what it would cost. He insisted it was the right thing to do in the face of widespread local opposition.
Asked whether McGuinty should have apologized, Wynne said she was also a part of the government at the time the decisions were made and put no distance between herself and McGuinty.
"I'm in this chair now and it's my responsibility to level with the people of Ontario about how I see the situation and how I feel about the situation and what I'm hearing from them," she said.
"I'm hearing people say that they want to hear an apology for the parts of this that our government messed up. You know, the mistakes."
The opposition parties say the Liberals intentionally misled the public about the true cost of cancelling the gas plants.
Wynne has insisted she's taken responsibility for the cancelled plants.
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