Ronald Acuna Jr. added three hits and Ozzie Albies had two for the Braves (96-50), who clinched the National League East title for the sixth consecutive season. The Braves are the first team to win a division in the majors this year.
Kevin Pillar had an RBI double and a single as Atlanta won three of four games in the series.
Braves starter Spencer Strider (17-5) went seven innings and allowed four hits and one run with nine strikeouts and two walks.
Kirby Yates threw a scoreless ninth inning for his fifth save in eight chances.
Bryson Stott hit an RBI single for the Phillies, who fell to 79-67.
Phillies starter Cristopher Sanchez (2-4) gave up eight hits and four runs with a career-high 10 strikeouts in 7 1/3 innings. He walked one.
The Braves went ahead 2-0 in the first when Riley ripped a two-run homer, a 447-foot shot to center. It was Riley's 35th home run of the season.
The Phillies sliced the deficit in half in the bottom of the first when Stott hit his run-scoring single. Kyle Schwarber scored on the play after opening the frame with a walk.
Riley added a sacrifice fly to center in the third for a 3-1 lead.
In the fourth, Pillar hit his RBI double for a 4-1 advantage.
The Phillies managed only three hits through six innings — singles by Stott, Brandon Marsh and Alec Bohm.
Bohm had his base hit with two outs in the sixth, but Stott flied out to left to snuff any hopes of a rally.
Acuna singled with two outs in the seventh and stole his 66th base of the season, advancing to third on the play thanks to a throwing error by catcher Garrett Stubbs. Albies walked and Riley flied out in foul ground on a sensational sliding catch by Stott near the wall down the first base line.
—Field Level Media