Morgan finished at 14-under 202 to capture his 25th tour victory and take third place on the Champions Tour all-time wins list.
"It was really great to come here and play well and win," said Morgan. "There was a couple of times I felt like I was letting it get away, but I guess it was just my day today."
Irwin -- who leads the tour’s all-time wins list and was going for his 46th tour title -- shot a 3-under 60 Sunday to finish at 12-under 204.
Tom Watson shot a 3-under 69 Sunday and finished in third place at 10-under 206.