On August 23, 2017, against the Pittsburgh Pirates, Hill was pitching a perfect game through eight innings until a fielding error by Logan Forsythe in the ninth. He remained in the game for the tenth inning but his no-hitter was ended by a walk-off home run by Josh Harrison, which was the first extra-innings walk-off home run to break up a no-hitter (and second walk-off hit, following Harvey Haddix in 1959). This was the first perfect game broken up by a ninth-inning error in MLB history, and Hill became the first pitcher since Lefty Leifield of the 1906 Pittsburgh Pirates to lose a decision despite throwing at least nine innings with one or fewer hits and no walks allowed. For the 2017 season, he was 12–8 with a 3.32 ERA in 25 starts. Hill pitched in one game in the 2017 NLDS, allowing two runs in four innings and in one start in the 2017 NLCS, he limited the Cubs to one run on three hits in five innings, while striking out eight. In two starts in the 2017 World Series, he allowed a total of two runs on seven hits in innings with 12 strikeouts.