In 1970, Morton compiled an 18–11 record for the last-place Expos and was the National League Rookie of the Year, chosen over Bernie Carbo, Larry Bowa and César Cedeño. He had a 3.60 ERA in 43 games pitched, having 10 complete games, four shutouts while throwing 284.2 innings, 125 walks and 154 strikeouts, the latter three being career highs. He received votes for the Cy Young Award and the Most Valuable Player voting, finishing 9th and 27th, respectively. That same year he also received the "Sporting News" Rookie of the Year Award, becoming the first Montreal player to receive the honors.