He was the senior litigation partner in Rotorua firm East Brewster from 1979-98.
Mr Ronayne, who specialised in criminal prosecutions, regulatory advice, civil litigation, disciplinary proceeding, mediation and arbitration, has clocked up 34 years' experience in all areas of litigation. He is also a trained mediator.
He said becoming a judge was not something he had always aspired to be, but he did not think twice about accepting the judicial appointment when asked.
"I feel very proud to accept this appointment and feel very privileged to be able to serve in this way. I'm very excited about this new challenge and of the new direction," he said.
Mr Ronayne said he would miss the Western Bay.