Mediate was rarely challenged in breezing to his second Champions Tour win of the season, finishing at 22-under-par 191.
His previous win came at the Allianz Championship to kick off the 2013 season.
Tom Byrum also carded a 64, claiming sole possession of second place at minus-15.
Sharing third one shot further back at Canyon Meadows Golf & Country Club were Duffy Waldorf (65) and Kirk Triplett (67).
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