The plea was entered in New York Wednesday before a Manhattan Federal Court judge.
If the 28-year-old actor remains in treatment for three months and stays out of trouble for six months, he'll be able to withdraw the plea and the case will be dismissed.
Disorderly conduct is a violation, not a criminal offense.
LaBeouf was accused of disrupting a performance of "Cabaret" starring Alan Cumming.
His publicist has said the episode stemmed from an alcohol problem and that the actor has since gotten treatment. LaBeouf is best known for appearing in the first three "Transformers" films.