Zimmerman, who had hit a grand slam the night before, connected for a two-run homer off Dickey in the sixth inning and the Nationals defeated the Braves 3-2 on Thursday night behind a 10-strikeout effort from Stephen Strasburg.
Strasburg (2-0) allowed two runs over seven innings while giving up six hits and walking two. He threw 76 of his 103 pitches for strikes.
Shawn Kelley, elevated to closer duties after Blake Treinen struggled, allowed a two-out single to Kurt Suzuki and walked pinch-hitter Tyler Flowers before retiring Ender Inciarte on a fly ball to pick up his second save.
Zimmerman scored the Nationals' first run after a double and finished the series 7-for-12 with seven RBIs. He is batting .389 with five homers and 13 RBIs.
Zimmerman's blast to center field came on a 1-0 knuckleball that stayed up after Dickey had walked Bryce Harper with two outs in the sixth.
Dickey (1-2) allowed three hits and a pair of walks over seven innings while getting 12 ground outs and striking out three. He was pulled for a pinch hitter after 73 pitches.
The Nationals have won 32 of 41 games against the Braves since the start of the 2015 season.
Michael Taylor's sacrifice fly in the second scored Zimmerman, who had doubled off Dickey, to give the Nationals a quick run, but the Braves tied it the bottom of the inning. Dickey got his third RBI of the season on a bases-loaded infield roller.
The Braves went ahead in the fourth on Kurt Suzuki's sacrifice fly after a double by Brandon Phillips off Strasburg.
NOTES: LF Matt Kemp, activated by the Braves after missing 10 games with a hamstring strain, was 0-for-4 with three strikeouts. ... 2B Daniel Murphy was out of the Washington lineup because of tightness in his right leg. The Nationals hope he will be available when they open a series at the New York Mets on Friday. ... Nationals LF Jayson Werth (groin spasm) wasn't available after leaving Wednesday's game during an at-bat. ... INF Johan Camargo was optioned back to Triple-A Gwinnett by the Braves to make room for Kemp. ... The Braves made a bullpen switch, optioning RHP Luke Jackson to Gwinnett and recalling RHP Aaron Blair. ... SS Dansby Swanson, 2-for-25 on the homestand, was out of the Braves lineup for the first time this season. ... The Braves begin a nine-game road trip at Philadelphia on Friday, with RHP Barolo Colon (1-1, 4.24 ERA) facing RHP Jeremy Hellickson (2-0, 0.82 ERA). ... RHP Tanner Roark (2-0, 3.50 ERA) will start for the Nationals at New York against RHP Jacob deGrom (0-0, 1.89 ERA).