Unions will wrap up more than 20 major rallies campaigning for changes to workplace laws with protests in Brisbane and Canberra.

Australian Council of Trade Unions secretary Sally McManus will be in Queensland's capital as the month-long series of rallies concludes.

The ACTU estimates more than 250,000 people have hit the streets around Australia in 22 demonstrations across major cities and regional centres.

ACTU president Michele O'Neil, who will address unionists in Canberra, said balance needed to be returned to Australia's industrial relations system so workers could get fair pay rises.

“This political protest is aimed at making Scott Morrison and federal politicians listen," O'Neil said.

“Our wages are going backwards, families are struggling, and too many people are stuck in insecure work," she said.

The union movement's ambitious reform agenda includes changes to workplace bargaining and measures to increase job security.

The coalition government and employer groups have warned against the campaign's aims, raising concerns the proposals would stifle the economy and give unions too much power.