Shannon MacMillan played for the University of Portland where she won the Hermann Trophy for the best female collegiate soccer player of the 1995 season. She earned All-America honors from 1992 to 1995.
As a senior at Portland, she won the Honda Sports Award as the nation's top soccer player. MacMillan is a FIFA Women's World Cup champion and Olympic Gold and Silver Medalist. Named U.S. Soccer Athlete of the Year for 2002, MacMillan played for the United States women's national soccer team from 1994 to 2006 and was part of the 1999 FIFA Women's World Cup-winning team. She won gold with the team at the 1996 Summer Olympics and silver at the 2000 Summer Olympics.
In 2016, she was inducted in the National Soccer Hall of Fame.