Irwins 21-under-par 195 total was six shots better than the previous record set by Jim Dent in 1994 and matched by Graham March in 95.
'It just came together this week, said Irwin, whose 31st tour win netted him $210,000. I played extremely well.
Australian Stewart Ginn shot 67 to finish in second place, four shots back of Irwin.
Irwin started the day tied with Gil Morgan. However, Morgan carded an even-par 72. His round included a double bogey at the 18th. He finished seven shots back of his nemesis, in fifth place.
Irwin took sole possession of the lead with a birdie and a Morgan bogey at the 8th. He then added to his advantage with two birdies over his next three holes.
A 91-minute rain delay wasnt able to stop Irwins momentum on Sunday. Leading by three when the showers subsided, Irwin carded two more birdies before parring his final four holes in Birmingham, Ala.
Full-field scores from the Bruno's Memorial Classic