Leeza Ormsby, aged 37, was arrested in February in her villa in the tourist area of Kuta on the popular resort island.
Police found the joint in her bag, as well as 27g (almost one ounce) of hash and ecstasy pills weighing 132g in a cupboard.
However police later said they had decided only to seek charges against her over the joint and the other drugs would form part of a separate investigation, meaning she escaped a potentially heavier sentence.
Indonesia has some of the world's toughest anti-narcotics laws, including the death sentence for drug-smuggling.
Ormsby was formally charged at Monday's hearing, with prosecutor Ni Luh Putu Oka Ariani telling the court in the Balinese capital Denpasar that she had illegally been in possession of 0.30g of hash.
As well as possession, she was also charged with consumption of an illegal drug.
The offences carry a minimum of four years and maximum of 12 years in prison, as well as a maximum fine of $86 000.
Foreigners are regularly caught with drugs on hard-partying Bali, and there are several foreign nationals on death row for drugs-related offences in Indonesia.