Yingluck was due to hear the verdict on Aug. 25, but failed to show up, surprising hundreds of supporters, who had gathered at the court.
Aides said she had fled Thailand, fearing a harsh sentence.
In August, Reuters reported that she had escaped to Dubai, where her brother, former Prime Minister Thaksin Shinawatra, owns a home.
Yingluck, who swept to power in a 2011 general election, introduced a rice subsidy scheme that proved wildly popular with farmers but which the military government says caused billions of dollars in losses.
Her government was ousted by the military in 2014.