It was the first tournament victory for Blake since 1991 when he won the Shearson Lehman Brothers Open and Argentina Open in 1991.
Blake shot a 3-under 68 Sunday to get to 13-under for the tournament but he was matched by John Cook, who also shot a final-round 68; Mark O'Meara, with a 67 Sunday; and Peter Senior, whose third-round 64 was the best score Sunday.
O'Meara and Senior each missed short par putts on the third playoff hole, leaving Cook and Blake to decide the tournament.
The same pair met in a playoff at the Outback Steakhouse Pro-Am earlier this year, with Cook taking the event on the first extra hole.
But this time, after Cook missed an 18-footer for birdie on the fifth playoff hole, Blake made a 6-foot birdie putt on the par-4 10th and won the playoff and a first-place prize of $456,000.