In fading light Sunday on the Stadium Course at PGA West, Rahm finished off Landry for his second PGA TOUR title and fourth worldwide victory in a year. The 23-year-old Spaniard will jump from third to second in the world ranking.
Rahm overcame surprising par-5 problems in regulation to shoot 5-under 67. Landry forced the playoff with an 11-foot birdie putt on 18 for a 68. They finished at 22-under 266.
Rahm missed a chance to win on the first extra trip down the 18th when his 9-foot birdie try slid left, and on the second, Landry's 8-footer to end it went by to the right. They missed long birdie tries on the third extra hole, the par-4 10th.