The investigation, dubbed Project Opapa, looked into people allegedly recruited from Hungary to work in the local construction industry.
Gizella Domotor, 43, Anna Lukacs, 37, and Gyozo Papai, 42, were arrested in Toronto without incident. All three were wanted on Canada-wide arrest warrants.
The three accused are in custody awaiting bail at a Hamilton courthouse.
RCMP Insp. Steve Martin said the three people arrested are believed to be the remaining at-large members of the Opapa human trafficking ring.
In April, Ferenc Domotor, 49, was sentenced after previously pleading guilty to being part of a criminal organization, conspiracy to traffic in human beings and coercing victims to mislead immigration authorities. He is believed to be the leader of the ring.
Victims recruited in Hungary, brought to Canada
As many as 19 people, all from Hungary, were brought to Canada against their will, forced to work from dawn to dusk, held in basements and fed table scraps, the CBC's Aaron Saltzman was told in April.
"Their passports taken away, their families threatened with violence back home if they left — until one did, and the RCMP brought down the entire ring," Saltzman said.
The trafficking ring targeted vulnerable men from Hungary, promising them jobs and an easy life. Once in Canada, they were forced to claim refugee status, apply for welfare and work in construction jobs without pay.