Shortly after graduating early from the University of California, Berkeley, where she played for the California Golden Bears, Morgan was drafted number one overall in the 2011 WPS Draft by the Western New York Flash. There, she made her professional debut and helped the team win the league championship. Morgan, who was 22 at the time, was the youngest player on the national team at the 2011 FIFA Women's World Cup, where the team was runner-up. At the 2012 London Olympics, she scored the match-winning goal in the 123rd minute of the semi-final match against Canada. She finished 2012 with 28 goals and 21 assists, joining Mia Hamm as the only American woman to score 20 goals and provide 20 assists in the same calendar year and making her the sixth and youngest U.S. player to score 20 goals in a single season. She was subsequently named U.S. Soccer Female Athlete of the Year and was a FIFA World Player of the Year finalist. Morgan also helped the United States win their titles at the 2015 and 2019 FIFA Women's World Cups, where she was named to the Dream Team for both tournaments, while she won the Silver Boot in 2019.