The left-handed-hitting Whitesell, 27, posted a .346 on-base percentage in 46 games with the D-backs last year and was 23-for-115 (.200) with two home runs and 15 RBIs in 53 career games with Arizona.
Whitesell has hit 113 home runs and posted .394 on-base and .492 slugging percentages in seven Minor League seasons.
Bruntlett, 31, joins Washington after playing the past two seasons with the Phillies. Bruntlett is a .231 hitter with 11 home runs and 72 RBIs in 512 career games in seven seasons with Philadelphia (2008-09) and the Astros (2003-07). Bruntlett can play all four infield positions and all three outfield spots.
Bruntlett is best known for turning an unassisted triple play in the bottom of the ninth inning against the Mets at Citi Field on Aug. 23.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.