 In the third game of 2018 World Series against the Boston Red Sox, Muncy scored the tying run in the 13th inning and then hit a walk-off home run in the 18th, ending the longest game in World Series history after seven hours and 20 minutes In the five games of the series, he hit .235 (four hits in 17 at-bats) with the one home run.In 2019, Muncy was selected to the 2019 Major League Baseball All-Star Game as an injury replacement, his first all-star appearance, replacing Washington Nationals third baseman Anthony Rendon.. On August 30, 2019, Muncy was placed on injured list with a wrist fracture,.He finished the 2019 regular season, playing in 142 games, hitting .251 with 35 home runs and 98 RBIs.