Ryan Getzlaf had a goal and two assists for the Ducks (14-10-5), who became the first team in NHL history to rally back from four goals and win against a defending Stanley Cup champion. Aberg added an assist. Rickard Rakell and Hampus Lindholm each had a goal and an assist.
Miller, who made 19 saves, entered the game at 13:19 of the first period after Tom Wilson gave the Capitals a 3-1 lead. John Gibson made eight saves on 11 shots.
"It was a wild game to have it happen. It's probably the right way to do it," Miller said after Anaheim's fourth straight win. "I've had a lot of guys over the years put it on the line so I could get a win in my column, and tonight's a reflection of that kind of group effort."
WATCH: [All Ducks vs. Capitals highlights]
Chandler Stephenson, Nic Dowd and Evgeny Kuznetsov each had a goal and an assist for Washington (15-8-3), which had won seven straight. Braden Holtby made 19 saves, and John Carlson and Dmitrij Jaskin each had two assists.
"Should have shut them down there with a 5-1 lead," Backstrom said. "They shouldn't be able to come back. They're a good team and they've got some skill on there, so that's what's going to happen when we turn pucks over and give them room on the PP."
Aberg completed the rally when he scored off a pass from Getzlaf on the rush for his second goal of the period.
"An empty net," Aberg said. "I just tried to be patient not to rush it because I didn't want to miss that one. [Holtby] put his stick up and fortunately it went in."
Aberg's shot from above the right face-off circle deflected in off the post on a power play at 7:16 of the third period to make it 5-4 and Lindholm tied it on a power-play goal at 9:01. Before those two goals, the Capitals had killed off 20 consecutive power plays.
