Malcolm Turnbull is going back to where his political career began with a much anticipated address to mark the 25th anniversary of the Australian Republican Movement.

The Prime Minister will speak at the event on Saturday night which the movement hopes will press the reset button on the republican debate.

The gala event will be held in the Great Hall of Sydney University with the top tier tables costing $3000.

"We are absolutely thrilled that the Prime Minister has agreed to join us for our 25th anniversary commemoration," the ARM's national chairman, Peter FitzSimons, said.