The court considered her absence as an attempt to escape although she would earlier assigned her lawyer to notify the court that she could not attend the hearing of the verdict because she developed sickness from the imbalance of fluids in the ears. "I think she will definitely not flee", Boon Poomsida from Yasothorn province said.
A senior source in Ms Yingluck's Pheu Thai party later told AFP she was "likely in Singapore".
"I don't know Yingluck's whereabouts. She won't give up easily", supporter Vittawat Suwanpuk told the Times. So it is unlikely anyone tried to stop her leaving, or that they will try to get her back.
"I just learned that she did not show up [at court]", Prayut Chan-O-Cha told reporters.
If convicted, Yingluck has the right to appeal.
Thaksin has not returned to Thailand since.
That movement, pitted against a Bangkok-centered royalist and pro-military elite, has been at the heart of years of turmoil.
Yingluck was ousted from office by a Constitutional Court decision in May 2014, and shortly afterward the military took over again, dissolving the caretaker parliament, blockading streets in the capital Bangkok, and imposing martial law.
The source declined to say where she had gone, but Thailand's top immigration official said there were no records of Yingluck having left the country through proper channels. Yingluck also posted a message on her Facebook page urging followers to stay away, saying she anxious about their safety. The sheer number demonstrated the military's desire to show their control of the situation, an image spoiled by Yingluck's non-attendance.
The rice subsidies, promised to farmers during the 2011 election, helped Yingluck's party sweep the vote. Yingluck was also criticized for buying loyalty from her supporters through populism during her premiership without seriously addressing critical hurdles in democratization.
According to unconfirmed media reports, Ms Yingluck left home on Wednesday night in the vehicle of a high-level government official. It has earned $40 million from the sales but calculates the government lost billions because it couldn't export at a price commensurate with what it had paid farmers.
In a separate administrative ruling that froze her bank accounts, Yingluck was held responsible for about $1 billion of those losses - an astounding personal penalty that prosecutors argued Yingluck deserved because she ignored warnings of corruption but continued the program anyway.
Since the coup, Yingluck has been attacked by her enemies through several court cases.
Yingluck said the rice subsidy scheme was "beneficial for the farmers and the country" and that claims it lost money were wrong and motivated by political bias against her. He was later sentenced to two years in prison in absentia.