Democrat Lori Lightfoot, a 56-year-old former federal prosecutor making her first run for elected office, won the Midwestern city's mayoral race on Tuesday in a lopsided victory.
She beat Toni Preckwinkle, a career politician who is also black, by a wide margin of 74 to 26 percent with most ballots counted.
"We were up against powerful interests," Lightfoot said in a victory speech, with her wife and young daughter by her side.
"Today, you did more than make history, you created a movement for change," she told a cheering crowd.
Lightfoot will replace outgoing Mayor Rahm Emanuel, once a rising star in the Democratic Party and former President Barack Obama's first White House chief of staff.
Chicago will become the largest US city to have a black woman serve as mayor when Lightfoot is sworn in on May 20.
She will join seven other black women currently serving as mayors in major US cities, including Atlanta and New Orleans, and will be the second woman as well as the third African American to lead Chicago.
Related: Chicago Sun Times.