Sizemore, 44, admitted using drugs again and was ordered to report to a 90-day rehab center by March 23, with no leaves for work or otherwise, E! Online reported Friday.
Prosecutors said Sizemore failed a Jan. 23 drug test and was kicked out of his last treatment center for arguing with another patient.
It marks the second probation violation for the "Saving Private Ryan" star.
Sizemore is appealing his 2003 domestic violence conviction for hitting his former girlfriend, "Hollywood Madam" Heidi Fleiss.
Prior to this week's hearing, he had been shopping around a TV reality show called "Super Sizemore," chronicling his drug and legal woes.