Porcello began the 2018 season in Boston's starting rotation. On April 12, against the Yankees, Porcello took a no-hitter through 6+ innings until giving up a double by Aaron Judge. Porcello pitched through seven innings, giving up only two hits while striking out six as the Red Sox won, 6–3. During the regular season, he made 33 starts for the Red Sox, going 17–7 with a 4.28 ERA in innings. The Red Sox finished with a 108–54 record and went on to face the Los Angeles Dodgers in the World Series. Porcello was Boston's starting pitcher in Game 3, getting a no decision in an extra innings loss. The Red Sox went on to win the series in five games, giving Porcello his first career championship title.