Haeger received the good news before his start against the Indians at Dodger Stadium on Thursday and expressed excitement before the game.
"I feel like a little kid," Haeger said. "I just feel happy. It's like a dream come true. I've been waiting for an opportunity like this for a long time and it's finally here."
Haeger beat out right-handers Ramon Ortiz and Russ Ortiz for the final spot in the rotation after posting a 2.38 ERA in five Spring Training appearances.
"We'll give him a shot at it," Torre said. "You have to pick somebody and of the pitchers we still have in camp, the Ortizes, I'm comfortable that if need be they can work out of the bullpen."
Haeger is expected to make his first start during the Dodgers' three-game series in Florida next weekend with the start coming on Friday or Saturday. Torre said Haeger could even see some time in the bullpen during the week before his start because of the flexibility he brings as a knuckleballer.
The 26-year-old will be making his 26th appearance in the Majors as he carries a career 5.26 ERA over 53 innings with the White Sox, Padres and Dodgers.
But he has a career 3.79 ERA in Triple-A and posted a 3.32 ERA in 19 innings with the Dodgers last season, impressing Torre.
"Joe expressed that he liked the way that I threw and the composure on the mound and that was enough for him," Haeger said. "Obviously, coming from a guy like Joe, as highly regarded as he is in baseball, it gave me motivation to work hard in the offseason."
Haeger credited former knuckleballer Charlie Hough for helping him work on his knuckleball this spring and now he's ready to bring it into the regular season as the Dodgers' fifth starter.
"I think I threw the ball well in Spring Training and I feel good about that," Haeger said. "It makes me feel good heading into the regular season, and physically I feel ready. The next step is to have a good season and try to bring a World Series here."