After interviewing Irwin, the Office of Workplace Health and Safety said Thursday there was not enough evidence to suggest that he and his Australia Zoo reptile park had violated any safety regulations.
Irwin was reprimanded by Queensland's Department of Family Services after the Jan. 2 stunt, but the agency took no action against him. Police also declined to file charges.
Irwin, the TV host of the "Crocodile Hunter" wildlife program, stunned onlookers by carrying his son, Bob, into a crocodile pen during a wildlife show. He tucked the infant under one arm while tossing the 13-foot reptile a piece of meat with the other.
Under workplace safety laws, unauthorized people cannot enter a crocodile enclosure that is part of a public display. But there was no evidence Irwin did not have control of the child, said Gordon Nutall, the state's industrial relations minister.
Inquiries established that measures were in place to manage the situation within the enclosure, he said.
A spokesman for Irwin declined comment after the decision.
Irwin has steadfastly defended himself against criticism that he endangered his child. He has rejected comparisons between himself and pop star Michael Jackson, who sparked worldwide condemnation when he dangled his baby out of a hotel window in Berlin in November 2002.
"It's all about perceived danger; I was in complete control," Irwin said at the time of his stunt.
"People say, 'Well, what if you had fallen?' But for that to take place, a meteorite would have had to come out of the sky and hit Australia."