Selected by the Tigers in the 2007 MLB draft, he made his MLB debut in 2009, and was the youngest player in the American League. His manager, Jim Leyland, chose to start him in the 2009 American League Central tie-breaker game over Nate Robertson, Eddie Bonine, and Armando Galarraga. After the 2014 season, the Tigers traded Porcello to the Red Sox. He struggled in 2015, but rebounded in 2016, leading the majors in wins and winning the AL Cy Young Award (becoming the first Red Sox pitcher since Pedro Martínez to do so) and the AL Comeback Player of the Year Award. He won the 2018 World Series with the Boston Red Sox, starting the third game of the series.