After blowing the four-shot lead he held entering Sunday's final round, Mickelson recovered to shoot 1-over 72 and win the Northern Trust Open for the second year in a row.
Mickelson finished at 15-under 269, edging Steve Stricker by a stroke. Fred Couples (69), K.J. Choi (69) and Andres Romero (70) tied for third, two shots back.
Stricker went into the clubhouse with the lead at 14-under after shooting 67. But Mickelson made consecutive birdies on Nos. 16 and 17 to take a one-shot lead and made a par putt on No. 18 to seal the win.