[3] In the 2011 US Youth Soccer National Championship Series, NASA 12 Elite II placed third in U-17 standings, and Sonnett was named to the U-17 Best XI as a midfielder.

[10][11] The following year, Fellowship Christian, with Sonnett as captain, reached the 2012 Georgia state championship game and again faced First Presbyterian Day School ultimately losing 0–1.

[12] She was also named the 2011–2012 Gatorade Georgia Girls Soccer Player of the Year;[13][14] Sonnett was the first ever athlete from Fellowship Christian School to win the award.

[13][12] In early February 2012, Sonnett signed her national letter of intent to play for the University of Virginia in the fall of 2012 on an athletic scholarship.

[2][20] During her sophomore season, Sonnett earned 2 goals and 5 assists and started all 26 games, playing a total of 2,341 minutes and setting single-season record at UVA.

[19] Sonnett helped lead UVA to their first College Cup in 22 seasons, losing in the tournament's semifinal after double overtime to UCLA in penalty kicks, 1–1 (2–4).

[19][24] In 2015, Sonnett spent the summer playing for pro-am team Atlanta Silverbacks, in the final season of the USL W-League.

[25] Mid-season in October 2015, Sonnett earned her first call-up and started her first cap (as center back) for the senior United States women's national soccer team against Brazil.

[28] She led UVA to the quarterfinals of the 2015 NCAA women's tournament, losing to Rutgers University after double overtime in penalty kicks (6–7).

[2][27][30][31] Sonnett left Charlottesville a semester early to enter the NWSL (after being drafted as the number one pick by Portland Thorns FC in January 2016) but ultimately did graduate with a degree in sociology from UVA.

[46] On August 18, 2020, having been unable to play for Orlando, Sonnett joined Swedish Damallsvenskan club Kopparbergs/Göteborg FC on a short-term contract until November 2020.

[51] In 2021 Sonnett appeared in 18 regular season matches for the Spirit [52] helping Washington notch their first NWSL Championship by defeating the Chicago Red Stars, 2–1 in extra-time at Lynn Family Stadium in Louisville, Kentucky, on November 20, 2021.

[57] She was one of four national team players who joined Gotham as free agents that off-season along with Crystal Dunn, Tierna Davidson, and Rose Lavelle.

[13][14][62] Sonnett received call-ups for the United States women's national under-23 soccer team training camps in April and December 2013.

[70][71][72] Although Sonnett was called up to the USWNT U-23 training camp in Lakewood Ranch, Florida in April 2015, she was not named to the roster for the 2015 Four Nations International Nordic Tournament held in May 2015.

[73][74] On October 16, 2015, Sonnett received her first senior call-up to the U.S. women's national soccer team (USWNT) from Jill Ellis.

[91][92][93][94] In July 2016, Sonnett was named an alternate for the USWNT at the 2016 Rio Olympic Games, along with Ashlyn Harris, Sam Mewis, and Heather O'Reilly.

[101] Sonnett was called up for both the January and February training camps and was named to the roster for the 2017 SheBelieves Cup tournament in March but did not see any playing time.

[115][116] Sonnett started all three games at right-back during the Tournament of Nations and registered an assist to Alex Morgan's goal in the 26th minute against Japan.

[119][120] She appeared in three of the five match-ups during the tournament, including the game (6–0 win over Jamaica) which ultimately qualified the USWNT for the 2019 FIFA Women's World Cup.

[124][125] Sonnett attended the USWNT training camp in January held in Portugal and started in the friendlies versus France and Spain that same month.

[145] Following the January camp, she was named to the 20-player roster for the 2020 CONCACAF Women's Olympic Qualifying tournament held in late January/early February 2020.

[150][151] Sonnett was also named to the 23-player roster for the 2020 SheBelieves Cup and played all 90 minutes in the match against Spain at left back, aiding the USWNT to ultimately capture the tournament title on March 11, 2020.

[157] At the conclusion of camp, Sonnett appeared in both international friendlies as a full back against Colombia and registered an assist to Megan Rapinoe's goal during the January 22 match-up.

[163] In the 2022 CONCACAF W Championship tournament in Monterrey, Sonnett scored her first career international goal on her 69th cap in a 3–0 semi-final win against Costa Rica.

[166] On July 24, 2021, Sonnett made her Olympic debut in a group stage match against New Zealand, playing the full 90 minutes and resulting in a 6–1 win.

[171][172] She appeared as a substitute in the gold medal game against Brazil, which the United States won 1–0 on a goal from Mallory Swanson.

[174] Sonnett is close friends with current and former teammates Rose Lavelle and Sam Mewis, as noted in multiple podcasts and media appearances.