The "Mean Girls" actress was booked into the Century Regional Detention facility in Lynwood at 8:50 p.m. Sunday, in what was expected to be a short stay because of jail overcrowding.
Deputy Tony Moore said Lohan was released early Monday, but didn't have an exact time. News crews staking out the jail said she left at 1:40 a.m. in a black Cadillac Escalade sport utility vehicle, and that she was in her Venice home by 2 a.m.
Lohan had until Nov. 9 to report to the jail.
It's Lohan's fifth jail sentence since being arrested twice for drunken driving in 2007.
On Wednesday, a judge ordered jail time because Lohan recently violated court orders by getting booted from a community service assignment at a women's shelter.
The judge imposed a complicated sentence, telling Lohan that she will now have to perform all of her community service at the county morgue or risk serving an additional 270 days in jail.
The sentence also requires Lohan to undergo psychotherapy sessions and appear monthly at court hearings between December and March.
The judge also said Lohan can no longer leave the country and needs the permission of her new "no-nonsense" probation officer to travel outside California.
Jail overcrowding has led to significantly shortened jail terms.
In 2007, Lohan spent 84 minutes at the jail before being released, and in the past she has served about 20 percent of her sentence, which is roughly six days.
Lohan will have to serve 423 hours at the county morgue, where for nearly two weeks she has been mopping floors, cleaning bathrooms and washing dirty sheets.