Cain, who threw the 22nd perfect game in Major League history on Wednesday against the Astros, earned the weekly award for the first time in his career.
The right-hander struck out 14 batters in the 10-0 win against the visiting Astros, becoming the first pitcher in the 130-year history of the Giants franchise to record a perfect game.
The 14 strikeouts were a career high and tied Sandy Koufax's record for most strikeouts recorded in a perfect game (Sept. 9, 1965). It was also the highest strikeout total in a no-hitter since Nolan Ryan struck out 16 on May 1, 1991, against Toronto.
Cain, who also singled and scored on a Gregor Blanco home run in the fifth inning of the game, became the first pitcher ever to score a run in a perfect game.
The two-time All-Star has won a career-best seven consecutive decisions, and owns an 8-2 mark on the season with a 2.18 ERA.
Cain joins Philip Humber as the only other pitcher to toss a perfect game this season, and it marks just the third time in Major League history that two perfect games have been recorded in the same season (1880 -- Monte Ward and Lee Richmond; 2010 -- Roy Halladay and Dallas Braden).