Washington has lost nine straight, tying this season's longest dry spell and the worst skid since the Nationals moved from Montreal in 2005.
Rollins was hitting just .200 against Washington this season (7-for-35) before going 2-for-4 with a walk, three RBIs and two runs scored.
Philadelphia starter Kyle Kendrick (9-5) earned his first win since July 1, giving up two runs and seven hits in 6 2-3 innings.
Werth's solo homer and Rollins' RBI groundout helped the Phillies go up 3-0 in the second. Rollins hit a two-run homer in the fourth to give Philadelphia a 5-2 lead.
Ryan Howard and Pat Burrell each added an RBI single in a three-run sixth that gave the Phillies an 8-2 cushion. Washington helped the Phillies by making three errors, two of which led to runs off starter John Lannan (6-11).
Nationals third baseman Ryan Zimmerman is day-to-day with a bruised hand after Kendrick hit him with a pitch in the third.
Zimmerman came out in the fourth, He recently spent 48 games on the disabled list with shoulder problems.
Notes: The Nationals went 5-19 in July. ... Washington acquired shortstop Alberto Gonzalez from the Yankees for minor league pitcher Jhonny Nunez. Gonzalez is expected to join Washington on Friday. ... The Phillies have homered in 22 of their last 26 games against the Nationals. ... Philadelphia's Shane Victorino got his eighth bunt hit of the season in the fourth, one of two infield hits he had in the game.
