Myra Lynne Williams, 28, was arrested last August when customs and narcotics agency officers confiscated 0.43 grams of crystal methamphetamine upon her arrival at Bali's airport from Melbourne.
A three-member panel of judges at the Denpasar District Court found Williams guilty of possessing and using a category one drug.
According the indictment, it was Williams's erratic behavior by refusing to queue up and even babbling while waiting for her passport to be stamped that drew attention from immigration officials, who contacted narcotics and customs officers.
Indonesia has very strict drug laws and convicted traffickers are often executed by firing squad. More than 150 people are on death row, mostly for drug crimes and about a third of them are foreigners.
Eighteen people convicted of drug-related offenses have been executed under the current administration of President Joko "Jokowi" Widodo.