Today, former Washington Nationals pitcher and fan-favorite Aaron Barrett announced that he will be retiring from baseball in a tweet.

Barrett was added to the Nationals' 40-man roster for the first time after the 2013 season, and after impressing during major league spring training, he made the Nationals' Opening Day roster for the 2014 season.[7] He made his debut in the ninth inning of the team's first game of the year against the New York Mets, striking out two while picking up his first career win.[8][9] Barrett became a trusted member of manager Matt Williams' bullpen and was included on the Nationals' playoff roster in the National League Division Series. Called on to pitch in Game 4 of the series against the San Francisco Giants, the rookie threw a wild pitch over the head of catcher Wilson Ramos while intentionally walking Pablo Sandoval, allowing Joe Panik to score the winning run from third base.

Midway through the 2015 season, Barrett began experiencing discomfort in his right pitching elbow. After he gave up three earned runs in an August 5, 2015, appearance against the Arizona Diamondbacks, the Nationals optioned him to the Class-AAA Syracuse Chiefs, but they voided the option and placed him on the disabled list for an elbow strain. On September 4, 2015, Barrett underwent Tommy John surgery, in which the ulnar collateral ligament of the elbow in his left arm was transferred to his right arm. Several bone spurs were also removed from his elbow. In December of 2015, Barrett had bone spurs in his ankle removed.

On July 23, 2016, while rehabbing at the Nationals' minor league complex in Viera, Florida, Barrett fractured the humerus bone in his right arm while pitching. Witnesses to the incident likened the sound of the bone-breaking to a gunshot.

Barrett appeared in a game for the first time since the 2015 season on September 7, pitching a scoreless inning in relief against the Atlanta Braves and picking up his first strikeout since August 1, 2015, as he caught All-Star Ronald Acuña Jr. looking on a slider. He made 3 relief appearances in 2019 with a 15.43 ERA.