Bernier served as Jonathan Quick's backup with the Kings over the past four seasons after being Los Angeles' first-round selection in 2006. He played in 62 career regular-season games with the Kings as well as one playoff game and had a 29-20-6 record, a .912 save percentage, a 2.36 goals-against-average and six shutouts.
The 24-year-old Bernier started just 14 games this season as a backup to Quick, who won the Conn Smythe Trophy last season and signed a 10-year, $58 million contract extension. Bernier played well this season despite the limited playing time, posting a 9-3-1 record with a goals-against average of 1.88 and a save percentage of .922.
Bernier has been looking for more playing time, and the Kings have been looking to deal their talented backup goalie, who is eligible for restricted free agency this summer.
"Obviously I'm very excited," Bernier told ESPN.com's Pierre LeBrun. "Going to Toronto I think is a great challenge. It's great. They've got a really good young team, and hopefully I can fit in and have some success with them."
Kings general manager Dean Lombardi promised Bernier after the season that he would make his best effort to trade the goaltender so that he would have a better chance at playing games.
"I was very happy -- Dean is a man of his word," Bernier told ESPN.com. "I felt he would keep it, and he did. All the teams in the mix were great teams, but I have to tell you I'm so happy that it's Toronto."
Frattin played in 25 regular-season games with Toronto, scored seven goals, including three game-winners, and 13 points. During the playoffs, he played in six games and recorded two assists.
Scrivens played in 20 games with the Maple Leafs last season and posted a 7-9-0 record, two shutouts, a 2.69 goals-against-average and a .915 save percentage. He did not appear in the playoffs for the Maple Leafs.
The second-round draft selection acquired by the Kings will be in 2014 or 2015, which is Toronto's option.
ESPN.com's Pierre LeBrun contributed to this report.