Legislation to create the new rent cap system has been sent to the President for signature.
The Seanad passed the laws without a final vote being called.
Senators also passed a motion asking President Higgins to sign the legislation earlier than ordinarily allowed, so that the caps can be introduced immediately.
The laws passed after the Seanad voted down moves from Sinn Féin and Labour to link the cost of rent to inflation.
Labour's Kevin Humphreys said the rent caps would be of little use to people whose income did not keep pace with thye 4% annual allowable increases in rent.
He said: "Nobody, certainly in the private sector, will see their salaries increase by 12% over this period (covered by the rent cap).
"Wage inflation is very, very slight in the private sector."