The suspects had been held since August 26 by Armenian police, who confiscated their passports and telecom equipment while concealing their whereabouts from lawyers, according to Taiwanese authorities.
Taiwan's Mainland Affairs Council (MAC), its top China policy-making body, said it immediately lodged a protest with Beijing after being notified of the deportation.
"We have repeatedly demanded the Chinese side not to deport our people to mainland China. The Chinese side's action again disregarded our call ... And further hurt the feelings of Taiwanese people," it said in a statement.
Armenia's actions are the latest in a series of deportations of Taiwanese to China, with Taipei accusing Beijing of "abducting" citizens from countries that do not recognise the Taiwanese government.
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Analysts see the deportation cases as a Chinese bid to pressure Taiwan's new Beijing-sceptic leader Tsai Ing-wen, who took office in May.
But Beijing insists that Taiwanese fraud suspects should be sent to China to face trial because their telephone fraud crimes largely target mainland Chinese.
Taiwan's foreign ministry said it protested at the Armenian government's actions and vowed to report the incident to international human rights organisations.
Kenya deported dozens of Taiwanese accused of fraud to China last month and in April after they had been cleared of the charges.
Amnesty International has said the Taiwanese face potential "human rights violations" if sent to the mainland.
Taipei has also protested at the recent deportations of Taiwanese fraud suspects from Malaysia and Cambodia to China.
Relations between Taiwan and China have grown increasingly frosty since Tsai and her the Democratic Progressive Party came to power.