Anthony Rizzo added an RBI single in the seventh for Chicago.
Jason Motte (8-1) earned the win in relief, starting a string of four innings during which Cubs relievers didn’t allow a hit until pinch-hitter Nick Swisher doubled with one out in the ninth off of closer Hector Rondon.
London recovered to earn his 22nd save in 26 opportunities.
Miller (5-10) dropped his career-high ninth straight decision. Miller only allowed two hits, including Chris Coghlan’s solo homer, over the first five innings, but gave up five runs overall, three earned, after the Braves made a pair of critical errors.