Over €1.6m in unpaid wages has been returned to staff since the start of last year.
It's after the Workplace Relations Commission carried out over 6,000 inspections of businesses.
Large amounts of withheld wages were returned to staff in the food, retail and construction sectors.
Sinn Féin's workers' rights spokesperson, Louise O'Reilly, says a lot more money is due to employees.
"I think it's the tip of the iceberg, to be honest.
"I think if the WRC had more resources they would be in a position to do more investigations and I think they would be in a position to recover more money.
"A lot more needs to be done to make workers aware of their rights number one, and number two ensure that the WERC is adequately resourced so that they can investigate these situations and that money can be recovered for workers."
