Lohan was released at about 11:40 p.m. after posting $300,000 bail, Los Angeles County Sheriff's Department spokesman Steve Whitmore said early Saturday.
Celebrity website TMZ.com reported her release just before midnight.
Los Angeles Superior Court Judge Elden Fox had ordered Lohan held without bail during a brief hearing Friday morning, But his ruling later was overturned after the "Mean Girls" star's attorney, Shawn Chapman Holley, filed a late-afternoon appeal seeking bail.
Judge Patricia Schnegg, who is an assistant supervising judge of LA's criminal courts, issued a ruling shortly before 6 p.m., saying that since the starlet had been convicted of misdemeanors, she was entitled to bail.
The actress is not entirely free. She will be required to wear an ankle alcohol monitor and stay away from establishments that primarily sell alcohol.
She is also due back in court on Oct. 22, when the judge who curtly sent her to jail will decide what her punishment will be for failing a drug test roughly two weeks after he released her early from rehab.
At that hearing, Fox will formally determine whether Lohan, 24, violated her probation by failing a court-mandated drug test. The positive result came after the judge released Lohan early from inpatient rehab at Ronald Reagan UCLA Medical Center.
Fox did not say why he had ordered no bail for the actress Friday morning, or state what drug appeared in her system during the recent test.
Friday marked the third time Lohan has been sent to jail in a three-year-old drug and drunken driving case. She spent 84 minutes at the jail in 2007 and 14 days of a three-month sentence earlier this summer.
After news of her positive drug test broke last week, Lohan seemed to acknowledge an addiction problem on her Twitter feed.
"Substance abuse is a disease, which unfortunately doesn't go away over night," Lohan posted on Twitter on Sept. 17. "This is certainly a setback for me but I am taking responsibility for my actions and I'm prepared to face the consequences."
Fox had laid out a strict 67-day course of counseling, substance abuse meetings, monitoring and drug testing for Lohan in August. He asked probation officials on Friday to report how the actress had progressed on the treatment programs before Lohan's next court hearing.
The judge has said Lohan would be sent to jail for 30 days for each drug screening she skipped or failed and appeared to make good on the promise with his no bail order.
If he sentences her to jail in October, the amount of time he orders her to serve would be whittled down because of jail overcrowding and various credits.
Despite her release Friday, Lohan's continued court troubles have cast a pall over her career. She has been slated to star as Linda Lovelace in a biopic about the porn star, but the production schedule already was altered when Lohan was sent to jail in July.
In an e-mail sent before Lohan was granted bail, Matthew Wilder, the writer-director of the film titled "Inferno," said the film's producers "want her to do well." He did not address whether Lohan's role would be recast or the film further delayed.
AP Entertainment Writer Sandy Cohen contributed to this report.