The law increases the maximum penalty from a year in jail to five years in prison for knowingly making a false statement to police about a missing child.
Caylee's mother, Casey Anthony, was acquitted last year of murdering her daughter but convicted on four counts of lying to investigators.
Caylee wasn't reported missing until 31 days after she vanished in 2008 in Orlando.
Casey Anthony completed her four-year maximum sentence while awaiting trial on the murder charge.
She could have gotten up to 20 years in prison if the bill had been in effect at that time.
