Wearing a brown Pittsburgh Steelers jacket, jeans and carrying a brown paper bag, Zimmerman walked out of the John E. Polk Correctional Facility in Sanford, Florida, moments after midnight after posting bail and meeting other conditions set for his release at a hearing on Friday.
Zimmerman was met by another man and quickly climbed into a late-model white BMW that drove off. He made no comments to a handful of reporters gathered outside the jail.
Under conditions set by Judge Kenneth Lester Jr., Zimmerman must wear an electronic monitoring device and he may be allowed to leave the state. He also must observe a dusk-to-dawn curfew and is prohibited from consuming illegal drugs or alcohol or possessing a firearm.
Attorney Ben Crump, who represents Martin's parents, said the family was "praying and trying to trust" in the judicial process that allowed Zimmerman to be released from jail but hoped that he would not remain free for long.
"They were heavy hearted that the killer of their son was released from jail," Crump told Reuters.
"However, they hope that his freedom is temporary because the pain he has caused their family is permanent. They're never going to get Trayvon back." Zimmerman attorney Mark O'Mara, appearing in on CBS's "This Morning" program, said there had been no recent threats against his client but his whereabouts still are expected to remain secret until his next appearance in court.
Zimmerman shot and killed Martin in a gated community in Sanford in central Florida on Feb. 26 in an incident that prompted civil rights protests and a national debate over guns, self-defense laws and race in America.
No date has been set for Zimmerman's trial.
Zimmerman, who is white and Hispanic, has said he shot the 17-year-old Martin in self-defense in a confrontation that occurred as Martin was returning to his father's house in the community after buying candy from a convenience store.
Police initially declined to arrest Zimmerman, citing Florida's "Stand Your Ground" law, which allows people to use deadly force when they believe they are in danger of being killed or suffering great bodily harm.
The lack of an arrest led thousands to march in protest rallies in Sanford and across the country. The public outrage forced the Sanford police chief and regularly assigned prosecutor to step aside.
At the Friday hearing, Zimmerman apologized to Martin's family, stunning a rapt courtroom after he appeared in a suit and tie and with shackles around his waist and wrists.
Zimmerman's lawyer had requested bail of no more than $15,000. Prosecutors opposed his release and sought bail of $1 million.
Governor Rick Scott appointed Angela Corey as special prosecutor. She charged Zimmerman on April 11.
