They were arrested during a raid on an underground construction project in Hsinchu County after the Coast Guard Administration officials in Kaohsiung got a tip-off.
Of the 22, 13 were working immigrants, 6 were tourists and 3 were visiting their relatives in Taiwan.
Two Taiwanese employers could also be prosecuted for their involvement in the case for violation of the Employment Service Act, and face fines of $4,860 to $24,300, the report said.
Taiwan has become a sought after destination for Vietnamese seeking jobs overseas ever since it lifted a 10-year ban on certain categories of Vietnamese workers in 2015.
Vietnamese workers in the territory can earn $700 - $800 a month, three or four times the typical remuneration in Vietnam.
Last year, 65,000 Vietnamese workers were sent to Taiwan, accounting for nearly half of Vietnam's overseas workforce.