Morton regressed in the following two seasons with Montreal, plagued by low run support. For 1971, he went 10–18 with a 4.80 ERA in 36 games, having nine complete games and one save on 213.2 innings of work, with 84 strikeouts and 83 walks. His one save came on June 21, 1971 during the second game of an Expos-Braves doubleheader. Morton retired the final batter of the game in a 5-3 Expos win. In his final year with the Expos, he went 7–13 with a 3.92 ERA in 27 games, having three complete games in 172 innings, having 51 strikeouts and 53 walks. On February 28, 1973, he was traded to the Atlanta Braves for Pat Jarvis.