Singapore previously witnessed violence on such a scale during race riots in 1969.
The other three men discharged from rioting charges would be issued police advisories but can remain in Singapore.
Earlier this week, a civil group questioned the "arbitrary deportation" of the men, citing the UN Special Rapporteur on the Human Rights of Migrants.
A Committee of Inquiry was set up by Prime Minister Lee Hsien Loong's order to probe the riot. He had warned that "full force of the law" would be used against trouble-makers.
At the same time, the premier said his government would treat foreign workers fairly and properly. "We do not stand for ill treatment or unfair treatment of foreign workers," Lee had said.
