The Warriors needed a win for a top-six finish in the Western Conference, BBC Sport reported.
And they scored a record 55 points in the first quarter to lead 55-27, as two-time MVP Stephen Curry finished with 26 points from 22 minutes.
The Los Angeles Clippers secured the other remaining play-off spot.
They won 119-114 at the Phoenix Suns to secure the number five seed and a rematch with Phoenix in the first round of the play-offs as the Suns had already secured the fourth seed.
The Clippers’ win left the Warriors as the sixth seed, meaning they will face the Sacramento Kings next.
The Los Angeles Lakers were hoping to snatch a guaranteed play-off spot on the final day and LeBron James scored 36 points with eight three-pointers as they beat the Utah Jazz 128-117.
But with the Clippers and Warriors both winning, they had to settle for the seventh seed in the West and a spot in the play-in tournament.
The Lakers will have home advantage tonight against the Minnesota Timberwolves, for whom Karl-Anthony Towns scored 30 points against the New Orleans Pelicans to win 113-108 and move past the Pelicans into eighth place.
All the play-off and play-in spots in the Eastern Conference had already been decided before the final day.
Teams ranked seven to 10 will compete in the play-in tournament, which features three games in each conference from 11-14 April, to determine seeds seven and eight for the play-offs.