A "very sad" Ms Jacobs, 50, made the shock announcement that she would be leaving the ABC during her Mornings program on Wednesday.

She made it clear it had not been her decision to leave the position, saying ABC management had told her her "services were no longer required on air".

Her last shift will be December 15. She will be replaced in 2018 by current Drive presenter Adam Shirley.

No explanation for her departure has been given by ABC management. There is speculation it is part of the ABC's youth and diversity drive and perhaps a signal it wants to merge its TV and radio operations.

Ms Jacobs' usually assured delivery was missing as her voice shook with emotion relaying the news to herlisteners.

"I've been very proud to be a voice for the people right across the region, to speak for the bush and the suburbs and the city," she said, on air.

"I've always tried to act with integrity and fairness. Not to give in to the bullies and to use the yardstick of common sense in the way I approach all issues. And if I've erred or failed, I've tried to honestly rectify that. Mostly, I've always tried to tell you the truth.

"You are such kind, smart, good people. You are the best of Australia. You are my neighbours, you're my community and it's been the greatest privilege to serve you.

"I'm not leaving Canberra or retiring."

Supportive comments came within minutes of Ms Jacobs making her announcement, including from Canberra Museum and Gallery director Shane Breynard who called her a "master broadcaster".

Others tweeted that it was "a terrible decision'' and that the "ABC is being gutted. It's really sad".

Chief Minister Andrew Barr, who fronted Chief Minister Talkback with Ms Jacobs, said it was "the end of an era for ABC Radio Canberra".

"I'm sure many will miss hearing Genevieve in the mornings," Mr Barr said.

"Chief Minister Talkback will not be the same. Genevieve has been a stalwart of Canberra's local media for many years and I wish her well in her career beyond the ABC."

Before going on air, Ms Jacobs emailed contacts telling them at 50 she had no plans to retire and while her career with the ABC was over, she certainly was "not out".

"I'm writing to let you know that about a month ago ABC Canberra manager Michelle Ainsworth told me that my services were no longer required on air. This makes me very sad," she said, in the email.

"I'll be telling the listeners this morning and I wanted to let so many of you who have been friends, guests, colleagues and comrades know too. I thank you all for your generous friendship and everything we've shared on the radio over the past decade.

"I do love nothing more than a good yarn about a big idea and so many of you have helped make that possible."

Ms Jacobs has been with ABC Radio Canberra, formerly 666 ABC Canberra, for a decade, gaining a reputation for presenting intelligent interviews, asking the tough questions when needed and understanding the local community.

It's understood that when Ms Jacobs objected to being dumped, ABC management did offer her a replacement position - as an off-air producer, a slap in the face for someone with her profile and following.

She is also sought-after as a professional MC and interviewer at events around Canberra, especially with the national institutions.

There are concerns within the ABC ranks that experienced presenters are being sidelined for younger broadcasters with less understanding of their audience. And there is a strong belief it comes direct from ABC managing director Michelle Guthrie.

A statement from ABC management made no mention that Ms Jacobs had been made redundant, only that she would "not be returning to ABC Radio Canberra in 2018"..

Michelle Ainsworth, editor ABC Canberra, thanked Genevieve for her contribution to local radio.

"Genevieve has made a terrific contribution to ABC Radio Canberra over the past 11 years," Ms Ainsworth said.

"She is a highly respected journalist and broadcaster who has presented a number programs and connected deeply with the community over local stories and issues. With Genevieve's departure from ABC Radio Canberra we'll take the opportunity to refresh the program in 2018.

"We wish Genevieve all the best for the future."