Corey Perry, Chris Wagner, Ryan Kesler and Rickard Rakell scored for the Ducks (45-23-13), who began an 8-0-2 run and pulled within four points of the Sharks for first place with a 2-1 victory in San Jose on March 18. Anaheim was nine points back on March 15.
The Blackhawks (50-23-8), who clinched the top seed in the Western Conference on Saturday, rested veterans Jonathan Toews, Duncan Keith, Marian Hossa and Brent Seabrook. It was their third straight loss (0-2-1).
"We're coming back Saturday with one more game," Chicago coach Joel Quenneville said. "We'll try to do the right things and get ready."
The Blackhawks went on the power play five seconds into the game when Ducks defensemen Josh Manson played the puck over the glass in his own end.
Anaheim then had back-to-back power plays early in the first and scored on the second when Perry beat Chicago defenseman Johnny Oduya to the right post and redirected a diagonal pass from Rakell for a 1-0 lead at 6:53.
Wagner made it 2-0 at 17:08 of the second period with his sixth goal. He was checked into the boards by Blackhawks forward Andrew Desjardins and fell to the ice near the red line. Wagner got up as the puck went behind the Chicago net and skated into the zone unnoticed. He tapped his stick, and Ondrej Kase passed to him for his second goal in as many games.
Kesler scored at 4:42 of the third period to put Anaheim up 3-0, and Rakell made it 4-0 with his 33rd goal at 14:43.
"We're playing really good hockey," Kesler said. "We continued that tonight."