Dahlkemper played collegiately for the UCLA Bruins, where she won the NCAA championship in 2013 and received the Honda Sports Award in 2014.

Following the Flash's relocation, Dahlkemper was voted NWSL Defender of the Year in 2017 and won successive league titles with the North Carolina Courage in 2018 and 2019.

[8] In January 2015, Dahlkemper was selected by the Western New York Flash in the 2015 NWSL College Draft as the third overall pick.

She was an important part of North Carolina's defense which broke the record for fewest goals conceded and repeated as NWSL Shield winners.

[17] She was named to the 2018 NWSL Best XI and was a finalist for Defender of the Year, losing to her Courage teammate Abby Erceg.

[18] North Carolina won the 2018 NWSL Championship with a 3–0 win over Portland, and didn't concede any goals in the playoffs.

[19] On January 16, 2021, Dahlkemper joined Manchester City of the English FA WSL on a two-and-a-half-year deal,[20] becoming the third American international to sign for the club during the 2020–21 season following Sam Mewis and Rose Lavelle's arrivals in summer.

[23] On November 22, 2021, Dahlkemper was announced as the first-ever player signing by NWSL expansion club San Diego Wave FC.

[2][30] Dahlkemper received her first call-up to the U.S. Women's National Team in October 2016 for a set of friendlies against Switzerland.

[31] Due to a sepsis infection contracted at the end of 2016, Dahlkemper was unable to appear for the U.S. WNT until June 2017.

In 2019, along with USWNT teammates Crystal Dunn, Megan Rapinoe, and Alex Morgan, Dahlkemper posed for the 2019 Sports Illustrated Swimsuit Issue in Saint Lucia.