Danny Green and Kawhi Leonard each scored 22 points, and San Antonio overcame an injury to Tony Parker to close out the Western Conference semifinals with a 104-82 victory on Wednesday night.
Patty Mills scored 18 points and Tim Duncan had 16 points and eight rebounds for San Antonio, which had four blowout victories in the five-game series.
It's the third straight conference finals appearance for San Antonio, which lost a heartbreaking seven-game series to the Miami Heat in last season's NBA Finals.
LaMarcus Aldridge had 21 points for Portland, while Damian Lillard added 17 points and 10 assists.