Yingluck was among the 155 people General Prayuth Chan-ocha, the army chief, summoned as part of his moves to restore peace in the country following months of turmoil that paralysed much of the government and caused deadly clashes.
Key figures connected with Yingluck's past government, and leaders of pro and anti-Yingluck administration protest movements were also summoned by the army.
Yingluck arrived at the Royal Thai Army auditorium in Thewes in a black bullet-proof Volkswagen van, with a vanguard of bodyguards.
Yingluck's appearance ended speculation that she had left the country after General Prayuth declared martial law, Bangkok Post reported.
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The army also banned 155 prominent political figures from leaving the country without permission and threatened to arrest those who disobey its orders.
The army yesterday suspended the Constitution and declared nationwide night curfew from 10 pm to 5 am after months of anti-government protests left the country in limbo.
The military junta also ordered all television and radio stations to suspend their usual programmes and replace with the army's statements.
Yingluck, whose government was in power when the unrest began in November, was removed from office earlier this month by the country's Constitutional Court over the appointments of top security officials.
Military officials haven't provided much explanation about the reasons for the summonses, saying it's necessary "to ensure smooth operation of restoration of peace and order.