In a special play-in series, added to the schedule since the league's resumption following the coronavirus break, eighth-placed Portland faced ninth-placed Memphis for the last spot in the Western Conference.
The Grizzlies had to win two straight games to grab the eighth seed whereas the Blazers only needed one and at the first attempt on Saturday they secured it – and a first-round match up with the Los Angeles Lakers.
Damian Lillard shone again, top-scoring with 31 points for Portland and adding 10 assists, while CJ McCollum scored 14 of his 29 points in the fourth quarter.
Memphis rookie Ja Morant piled in a career-high 35 points but a first appearance in the post-season ended agonisingly out of his reach.
It was the Trail Blazers sixth win in their last seven games as their late surge kept alive their post-season hopes.
And in that period point guard Lillard has averaged 39 points, including efforts of 61 and 51 points.
Portland return to the play-offs for the seventh successive season and reached the Western Conference Finals last year, where they were swept by the Golden State Warriors.