Judge Elden Fox made his ruling before hearing any argument from Lohan's lawyer, Shawn Chapman Holley, in Los Angeles Superior Court Friday morning.
The actress was handcuffed and taken into custody from court. She will likely be incarcerated until October 22, TMZ.com reports.
Lohan faced a judge Friday morning after violating her probation by failing a drug test, which she admitted to on Twitter.
Earlier this year, she spent 14 days in jail and less than a month in rehab for violating her probation related to a 2007 DUI arrest. She was sentenced to 90 days of each at the time.
Friday morning, Lindsay's father Michael told The Hollywood Reporter that Lohan should be sent to rehab instead of jail.
– The Hollywood Reporter