In the Raptors' season opener on October 17, Lowry scored 27 points on 5-for-6 from 3-point range and had eight assists in a 116–104 win over the Cleveland Cavaliers. On October 26, he had 20 points and 12 assists in a 116–107 win over the Dallas Mavericks, thus recording 10 or more assists for a career-best fourth straight game, becoming the first Raptors player to accomplish the feat since José Calderón had five in a row in March 2012. On October 30, in a 129–112 win over the Philadelphia 76ers, Lowry had 20 points and 13 assists, extending his streak of double-digit assist games to a career-best six. The career-best streak ended at nine. On November 21, he recorded his 13th career triple-double with 21 points, 17 assists, and 12 rebounds in a 124–108 win over the Atlanta Hawks. Lowry missed 10 games between December 14 and January 5 due to a sore left thigh (four games) and a sore lower back (six games). On March 3, he scored a season-high 35 points in a 112–107 overtime loss to the Detroit Pistons. On March 8, he had 13 points, 12 assists, and 11 rebounds in a 127–104 win over the New Orleans Pelicans. In Game 1 of the Eastern Conference Finals, Lowry scored 30 points and had seven 3-pointers in a 108–100 loss to the Milwaukee Bucks. His seven 3-pointers was a season high, a playoff career high, and one off his career high. In Game 5 against Milwaukee, Lowry surpassed DeMar DeRozan (1,117) as the franchise's postseason scoring leader. In Game 6, he scored 17 points to help lead the Raptors into the NBA Finals for the first time with a 100–94 victory. In Game 6 of the 2019 NBA Finals, Lowry recorded 26 points, 10 assists, and seven rebounds in a 114–110 series-clinching win over the Golden State Warriors, thus helping the Raptors win their first NBA championship in franchise history.