The new minimum wage of €7.65 an hour comes into effect today.
The rise was announced earlier this year after a recommendation by the Labour Court.
An estimated 57,000 workers who are currently being paid €7 an hour stand to gain from the increase.
The Government says the rise will benefit young and part-time workers in particular.
But the Chambers of Commerce of Ireland claim it will cost businesses a total of up to €250,000 an hour.
It is the fourth rise in the minimum wage since it was introduced in 2000.
