She was a finalist for the 2005 FIFA World Player of the Year award, and won an NCAA Women's Soccer Championship with Notre Dame in 1995.

Shannon Boxx announced her retirement from international and club soccer after winning the 2015 FIFA Women's World Cup.

[6] Boxx was diagnosed with lupus in 2007 when she was 30 years old, and went public with her diagnosis shortly before the 2012 London Olympics at which she won gold with the United States team.

[7] In 2020, Boxx joined the ownership group of Angel City FC of the National Women's Soccer League.

From 1991 to 1995, Boxx attended South Torrance High School, where she was a four-sport athlete, playing soccer, volleyball, softball and basketball.

She helped the team win the school's first NCAA Women's Soccer Championship in 1995, beating defending champions North Carolina in the semifinal.

[15] However, her playing time was reduced the following season, and in September 2002, she was sent to the New York Power, in a six-player trade that gave San Diego the first overall pick in the 2003 draft, used to select Aly Wagner.

[16] With New York, Boxx returned to form, starting all 21 games, scoring once and assisting a career-high eight times, and was named to the 2003 All-WUSA squad.

[15] In 2009, Boxx signed to the Los Angeles Sol for the inaugural season of Women's Professional Soccer and was named team captain.

She helped the club make a run to the playoffs in the second half of the season and win the quarterfinal match against the Boston Breakers.

[17] Prior to the call-up, following the suspension of WUSA, Boxx had planned to take a coaching position at Cal State-Dominguez Hills and pursue a graduate degree at Pepperdine University.

She was voted the player of the match against Canada by the FIFA Technical Study Group, who said Boxx "seized control of the game, spurred on her team-mates and finally scored the decisive goal in USA's victory".

Boxx helped the team reach the semifinal match against Brazil, but she was sent off after receiving two yellow cards, and the United States went on to lose 4–0.