He hailed his predecessor, Richard M. Daley, for reviving Chicago, once written off "as a dying city," but also promised "a new day."
Emanuel thanked President Barack Obama, whom he served as White House chief of staff, "who turned our nation around and who loves Chicago so much, he understood why I wanted to come home to get our city moving again."
He said education would be his top priority.
"Today, our school system only graduates half of our kids. And with one of the shortest school days and school years in the country, we even shortchange those who earn a diploma," the new mayor said.
He praised the Illinois Legislature for passing a longer school day and year and reforming teacher tenure.
"As some have noted," he said, "I am not a patient man. When it comes to improving our schools, I will not be a patient mayor."
Emanuel also called for tackling street crime and reforming city government.