Kennedy (18-4) became the first National League pitcher to reach 18 wins with his 21st quality start of the season. The right-hander held the Giants to one run on five hits over seven frames. He walked two and struck out six.
Paul Goldschmidt's homer broke a 1-1 tie in the fourth inning and he added an RBI single in the next frame as the NL West-leading D-backs pounded out 12 hits en route to a crucial win over second-place San Francisco.
Arizona won for the 10th time in 11 games and improved its lead over the Giants to six games.
San Francisco's Tim Lincecum (12-12) was the loser, giving up five runs on nine hits and three walks over five innings, while fanning seven.
Pablo Sandoval drove in both Giants runs with sacrifice flies.
Notable deaths of 2014 [PHOTOS]