In his first season as an NFL coach, Harbaugh guided the 49ers to a 13-3 mark, an NFC West title and the conference championship game. They beat New Orleans in the first round of the playoffs before losing the conference title game to the Giants.
"I think it was an amazing season," Harbaugh said. "In a lot of ways, beyond description. Incredible."
A former NFL quarterback and successful coach at Stanford, Harbaugh earned 45 votes from a nationwide panel of 50 media members who regularly cover the NFL. He easily outdistanced Green Bay's Mike McCarthy, who received three votes, and Denver's John Fox, who got two.
"I've said so often how proud I was of this team. I thought they played their hearts out," Harbaugh said. "I thought we were a well-coached team. They stand toe-to-toe and fight every time they go out onto the field."
Harbaugh said his only regret about his rookie year in the NFL was how the season ended, in a 20-17 overtime loss to the New York Giants in the NFC title game.
"It didn't have the ending that we wanted," he said. "The football gods had a different ending in mind."
Atlanta's Mike Smith was the last man to win the award in his initial season as an NFL coach, in 2008.