Anthony walked out of the Orange County jail in Orlando with her attorney at 3 a.m. EDT Sunday and was whisked away in a black SUV for parts unknowns.
The Orlando Sentinel said the vehicle was last seen entering a downtown parking garage where it was suspected Anthony and her party switched cars out of the view of the media.
WFTV-TV, Orlando, said Anthony wound up aboard a private plane that flew out of Orlando without filing a flight plan. The sheriff's department said it was not assisting in Anthony's security after her release.
The stealthy release was aimed at heading off any sizable protests from members of the public still outraged at the not-guilty verdict earlier this month. Anthony, 25, had been accused of killing 2-year-old Caylee in 2008 in order to unburden herself of the responsibilities of being a single mother.
The Sentinel said a handful of protesters gathered outside the jail where heavy security was in place. One of the demonstrators held up a sign asking Anthony to marry him. "Hopefully, she will just be able to see my sign," a smitten Tim Allen told the newspaper as he waited for Anthony to walk out. "Find me on Facebook. She can find out how to contact me."