In his second season, Thomas came into the year as the Saints' number one receiver after Brandin Cooks was traded to the New England Patriots. He was named to his first Pro Bowl. He finished the season with 104 receptions for 1,245 yards and five touchdowns. His 104 receptions finished third in the NFL, and his 196 receptions in his first two seasons in the league were the most in NFL history, passing Jarvis Landry's 194 set in 2015. Thomas appeared in his first career playoff game on January 7, 2018, against division rival Carolina in the . He recorded eight receptions for 131 yards in the 31–26 win. In the Divisional Round against the Minnesota Vikings, he had seven receptions for 85 yards and two touchdowns in the 29–24 loss. Thomas was ranked 81st by his fellow players on the NFL Top 100 Players of 2018.