The announcement was made at a morning tea with Bookfair volunteers at Mitchell on Wednesday.

Dr Nelson, who is director of the Australian War Memorial and a former cabinet minister and leader of the opposition, will help the 24-hour telephone crisis support service with official engagements, fundraising events and lobbying the government.

His first duty will be to deliver the key note address at Lifeline's Vintage Gala Ball later this month.

‘‘In my life as a family doctor and running after hours medical services, I too often saw the consequences of the pain and suffering in people’s lives, but I also saw the life changing and lifesaving impact of timely and appropriate intervention,’’ he said.

‘‘My further experiences in public life have enabled me to work in support mental health awareness and appreciate its importance to us all.”

Lifeline Canberra chief executive officer Mike Zissler said Dr Nelson's role was a "marquee day" for the service.

"Today's announcement is very significant in the history of our organisation," he said.

"This is our inaugural appointment of a patron and we are delighted that Dr Nelson made no hesitation in accepting our invitation.

"We are excited to have the support of an individual who has such a tremendous record of achievement in public life."