The `Mean Girls` actress was given the term as well as 480 hours of community service by Judge Stephanie Sautner in a Los Angeles court after testimonies were given against her in the case of a $2,200 necklace she allegedly stole from a top-end boutique and evidence was shown that she had violated her probation stemming from a 2007 driving under the influence (DUI) conviction.
Stephanie said: "She is to serve 120 days...forthwith. Perhaps she might see how women who have fallen on real hard times have to live and maybe she will change."
However, Lindsay`s lawyer Shawn Chapman said she would appeal the ruling, allowing her to leave the Lynwood Correctional Facility to return to her Venice Beach home after her $75,000 bail was paid.
Her grand theft charge was also downgraded to a misdemeanour by the judge, who said she often sees more serious cases get similarly reduced.
After Kamofie & Co jewellery store owner Sofia Kaman gave her case against the 24-year-old star, Stephanie agreed that Lindsay had been "brazen".
She said: "I see the intent here. I see a level of brazenness with, `Let me see what I can get away with here.` "
However, she said she was giving the actress - who pleaded not guilty in court yesterday (22.04.11) - "an opportunity" be reducing the charge.
Following the proceedings, Lindsay`s father Michael Lohan told RadarOnline.com: "I am not very happy. I don`t think her case was handled the right way."
According to the website, district attorney Jeanette Meyers will appeal the judge`s decision to reduce Lindsay`s charge from a grand theft to a misdemeanour.
She is now set to return to court on May 11 for a pre-trial hearing in her misdemeanour case, with the actual trial planned for June 3.