Corey Perry scored his 43rd goal as the Ducks finished off the second-place Sharks with a three-goal third period to earn the first back-to-back division titles in franchise history.
Matt Beleskey also scored for the Ducks as they pushed one point ahead of St. Louis for the overall lead in the Western Conference, although the Blues have a game in hand.
Jason Demers and Logan Couture scored for the Sharks, who have lost four of six down the stretch. Antti Niemi allowed three goals on 19 shots before getting pulled.
San Jose could have pulled within one point of the Ducks with a regulation victory, but Alex Stalock replaced Niemi midway through the second period after Maroon scored the tiebreaking goal on a stoppable shot through his legs.
Beleskey added a beautiful goal late in the period, and Jakob Silfverberg scored a short-handed goal on an empty net with 1:38 left to wrap it up.
Anaheim will face one of the West's two wild-card playoff teams — Minnesota, Dallas or Phoenix — in the first round.
The Sharks are locked into a first-round playoff rematch with the Los Angeles Kings, who eliminated them in a bruising seven-game series in the second round last spring. The California rivals are meeting in the postseason for the third time in four years.
The Ducks led the overall NHL standings for much of the season until St. Louis and San Jose pushed ahead of them last month. Anaheim reclaimed the lead two weeks ago and finally finished off the Sharks, who are in the playoffs for the 10th straight season.
In the biggest game of the regular season, Anaheim coach Bruce Boudreau made the mildly surprising choice to start the 20-year-old Gibson, who shut out Vancouver on Monday in his NHL debut, over longtime starter Jonas Hiller.
Maroon had the first multigoal game of his short career for the Ducks, coming through from the fourth line to give him 10 goals on the season — one more than Teemu Selanne, who assisted on both scores.
The Ducks also got a boost from the return of U.S. Olympic defenseman Cam Fowler, who had missed 12 games since March 14 with an injury.
Perry tied it for Anaheim on a drive to the net with 2.1 seconds left in the period, holding off Justin Braun with one arm and scoring with the other. The former NHL MVP trails only Washington's Alex Ovechkin in the league goal-scoring race.
Maroon put the Ducks ahead early in the second period with a wraparound goal off a setup from Selanne, but Couture tied it with a sharp-angled shot for his 22nd goal.
Selanne then got an outlet pass from Hampus Lindholm and sent a cross-ice feed to Maroon, who scored again 6:13 after his first goal to put Anaheim back ahead. Beleskey increased the Ducks' lead with an exceptional play, toe-dragging past a prone Brent Burns and beating Stalock for his eighth goal.
NOTES: Gibson was recalled because of an upper-body injury for Frederik Andersen. Hiller's Danish backup has missed three games. ... The Sharks scratched F Marty Havlat, who hadn't missed a game since March 8. ... Anaheim D Luca Sbisa sat out with an upper-body injury.