Kubel's two-run shot in the first inning put Arizona ahead to stay and his second -- a three-run clout -- highlighted a five-run fourth inning that put the game away for the D-backs.
The Arizona outfielder capped his big night with a solo shot in the sixth, becoming the seventh D-backs player to sock three long balls in a game. His 20 home runs and 70 RBI this season lead the team, and he is hitting .294.
Willie Bloomquist went 3-for-4 with three RBI as Arizona clinched its three-game series against the Astros.
Wade Miley (11-5) controlled Houston on one run over seven innings, yielding four hits and two walks while striking out nine.
Astros starter Dallas Keuchel (1-2) was rocked for seven runs (six earned) on seven hits while lasting only 3 1/3 frames.
Justin Maxwell went 2-for-4 with an RBI single for the losers.