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.

Morgan joined Portland Thorns FC in the NWSL's inaugural season in 2013 and helped the team win the league championship that year.

In 2017, Morgan signed with French team Lyon, where she won the continental European treble, which included the UEFA Women's Champions League.

[21] Morgan attended Diamond Bar High School, where she was a three-time all-league pick and was named All-American by the National Soccer Coaches Association of America (NSCAA).

[21] During a match against Stanford in the second round of the 2007 NCAA Division I Women's Soccer Championship, Morgan scored an equalizer with less than two minutes left in regulation time, resulting in a 1–1 draw.

[33] After the WPS later suspended operations in early 2012 due to legal and financial difficulties,[34] Morgan joined her national teammates Hope Solo, Sydney Leroux, Megan Rapinoe and Stephanie Cox on the Seattle Sounders Women for the 2012 season.

[48] On August 31, 2013, Portland captured the league's inaugural championship title after defeating regular season champions Western New York Flash 2–0; Morgan assisted on the second goal.

[64][65] Morgan made her 2016–17 UEFA Women's Champions League debut in the first leg of the quarterfinals on March 23 during the team's 2–0 win over VfL Wolfsburg.

[70] After recovering from the hamstring injury she suffered in the final, Morgan made her competitive return for Orlando on July 1 against the Chicago Red Stars.

[83] Still trying to regain fitness having not played since August 2019 and giving birth in May 2020,[84] Morgan eventually made her Spurs debut on November 7, 2020, appearing as a 69th-minute substitute in a 1–1 WSL draw against Reading.

[110][111] Due to the ACL injury that slowed her progress in 2007, Morgan was not called up to train with the United States under-20 women's national soccer team until April 2008.

On July 13, 2011, she scored her first FIFA Women's World Cup goal in the 82nd minute of the semi-final matchup against France, giving the U.S. a 3–1 lead and ultimately, the victory.

And, by herself, she comfortably out-scored and out-assisted her opponents, who combined for 21 goals and 12 assists in 32 matches against the U.S.[121] For her excellence on the field, U.S. Soccer announced Morgan as the 2012 Female Athlete of the Year.

[168] On May 26, she was named to the team's roster for two abroad June friendlies vs Sweden and Norway, but withdrew in the coming days after suffering a hamstring injury.

[177] Morgan then won the CONCACAF Women's Championship for the second time in her career after helping her team defeat Canada 2–0 in the final on October 17, where she contributed one goal.

[182] In the final on July 7, Morgan helped win a penalty that was later converted by Megan Rapinoe to open the scoring, as the United States defeated the Netherlands 2–0.

Morgan was awarded the tournament's Silver Boot; finishing as the joint-top scorer with six goals but losing out to Megan Rapinoe on a fewest minutes tiebreaker.

[193] Ahead of two abroad friendlies vs Australia in November 2021, USWNT head coach Vlatko Andonovski opted to leave a core group of veteran players off of his 22-player roster, which included Morgan.

[194] He cited that he needed to give roster spots to younger players to award them valuable minutes ahead of the 2023 FIFA Women's World Cup.

[197] Morgan helped the team win their third consecutive CONCACAF title and directly qualify for the 2024 Paris Olympics, scoring the game winner on a penalty kick in a 1–0 victory over Canada in the final.

[201] Morgan was also the joint top scorer of the tournament having scored three goals; tied with Julia Grosso, Jessie Fleming, and Khadija Shaw.

After teammate Mia Fishel tore her ACL during the final day of training for the 2024 CONCACAF W Gold Cup, Morgan was called to the squad as her replacement.

In 2011, James Frey, whose daughter was a fan of Morgan, approached her with the idea of creating a book series based around soccer for young girls.

[211] Frey's production company, Full Fathom Five, later produced a live-action kids comedy series based on the books, called The Kicks.

[213] Morgan has signed several endorsement deals with businesses including Nike,[214] Panasonic,[215] AT&T,[215] Chobani,[216] McDonald's,[217] P&G,[218] Mondelez International,[219] and Coca-Cola.

The Nine for IX documentary, The 99ers, in which she appeared focused on the success and legacy of the national team squad that won the 1999 FIFA Women's World Cup.

[253] In April 2015, Morgan joined Abby Wambach on American Idol to announce that the show's season winner would record the official song for Fox's coverage of the 2015 FIFA Women's World Cup.

[258] In June 2018, Morgan made her acting debut in the direct-to-video film Alex & Me with co-star Siena Agudong, where she portrays a poster of herself who comes to life.

[12] Although the name has been used more rarely over time, Morgan was given the nickname "Baby Horse" by her teammates on the U.S. women's national team for her speed, running style, and youth.

[273][274] On October 1, 2017, Morgan was one of a group of athletes visiting Epcot in Bay Lake, Florida, who were described in a police incident report as being "impaired and verbally aggressive....toward staff and around guests".