Cochran finished the 54-hole tournament at 11-under 205, hanging on for his fourth career Champions Tour victory after Blake missed a 10-foot birdie putt attempt on the 18th.
Blake fell out of the lead when he three-putted the par-three 17th for a bogey, settling for a final round of 3-under 69.
He finished one shot off the pace at minus-10.
Jay Haas (68) fell short in a bid for a fourth Principal title, finishing tied for seventh at minus-7.
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