Vladislav Gavrikov had two assists and David Rittich made 14 saves for the Kings (3-1-2), who have won two in a row.
"It's the never-ending battle of trying to make the play when it's there, and when it's not there, get in and put pressure on them because nobody likes to play under pressure," Kings coach Jim Hiller said. "I think the second half of the game we started to do that, and that's when we started to tilt the ice."
Ryan Strome scored and Lukas Dostal made 34 saves for the Ducks (2-2-1), who were outshot 38-15 two days after getting outshot 49-20 in a 4-3 overtime loss to the Colorado Avalanche.
"The last two games we've just been on cruise control. We're just watching the game," Ducks coach Greg Cronin said. "They've got to take ownership. The NHL is a fast game. If you don't skate to the finish line every time you're backchecking, forechecking, neutral zone regroups, you're not going to get the puck. It's that simple."
Kings center Anze Kopitar made a long pass off the boards to Kempe, who retrieved the puck, drove to the net on a breakaway and scored five-hole to give Los Angeles a 1-0 lead at 3:06 of the third period.
"When you see that ‘Kopi' or [Quinton Byfield] or whoever has the puck on their tape with time, especially if I have a D-man on me that I can beat, I'll just take off and those guys know that," Kempe said. "They've found me so many times before, so that's a good asset to have and I'm very grateful I'm playing with good passers."