Terry scored his 23rd goal of the season off a centering pass from Cam Fowler to give the Ducks a 1-0 lead at 2:44 of the first period.
Kopitar tied it 1-1 at 16:57 of the first period. Matt Roy took a slap shot from the right point, and Kopitar deflected the puck down by his feet before sweeping it into the net.
Kopitar finished with 74 points (28 goals, 46 assists), the 15th time in the past 16 seasons he has led the Kings in points.
"Fans or media, sometimes coaches and teammates, take [Kopitar] for granted and that's the wrong thing to do," McLellan said.
Kempe scored on a power play to put the Kings ahead 2-1 at 10:15 of the second period. Gibson attempted to stop Kempe's one-timer from the bottom of the right circle, but the puck crossed the goal line on the near side before he could sweep it away as the net was knocked loose. The goal was confirmed on a video review initiated by the NHL Situation Room.
Trevor Moore scored at 11:04 to extend the lead to 3-1. Ducks forward Frank Vatrano turned the puck over at his blue line, and Moore scored off a 2-on-0 break for his 10th goal of the season.
The Ducks cut it to 3-2 at 1:27 of the third on a redirection by Jones in front of the net.
Kempe scored his 40th goal of the season 40 seconds into a two-man advantage to make it 4-2 at 7:26.
Kempe did not score more than 16 goals in his first five seasons with Los Angeles but had 35 last season and 41 this season.
"A couple years ago, I felt like I had a lot of good looks, but I was a pass-first guy," Kempe said. "I figured out if I try to put the puck on net more, it will go in. It was kind of a switch that went off in my head. Coming into last year, I think, was the biggest step I took in terms of volume shooting."