In September, Donaldson finished third in the league in runs scored (20), on-base percentage (.454) and slugging percentage (.596), fourth in walks (17), seventh in batting average and tied for 10th in doubles. His 17 September extra-base hits also ranked seventh in the AL, while he had 11 multi-hit efforts.
He finished the season with 56 multi-hit games, the third-most in Oakland history behind Mark Kotsay (57 in 2004) and Miguel Tejada (57 in 2002).
Donaldson's 28-game on-base streak, which ended Sept. 24, was the longest by an Athletic in five years.
This is Donaldson's first Player of the Month Award and the first for an A's player since Eric Chavez earned the honor in September 2000.
Outfielders Coco Crisp (.274, seven homers, 19 RBIs) and Yoenis Cespedes (.314, six homers, 19 RBIs) also were under consideration for the award.
Cash Kruth is a reporter for MLB.com. Follow him on Twitter at @cashkruth. This story was not subject to the approval of Major League Baseball or its clubs.