The Raphoe man was made the county’s first citizen at Council HQ in Lifford a short time ago.
Fianna Fail had attempted to get its Buncrana councillor Rena Donaghey elected to the top post.
But Fine Gael, Sinn Fein, Labour and independents stuck to a pact agreed two years ago and voted Cllr McBrearty into the post.
His father Frank Snr, whose persecution led to the setting up of the Morris Tribunal investigation into Garda corruption, was in the chamber to see his son become Mayor. His wife and family were also there.
Mayor McBrearty vowed to work for all citizens of Co Donegal during the year ahead.
Earlier Cllr Ciaran Brogan (Fianna Fail) proposed Cllr Rena Donaghey for the position of Mayor saying he “had to be honest”.
There was a stony silence in the chamber when Cllr Brogan spoke.
“We will not and cannot support Frank McBrearty. No-one has caused as much destruction in this chamber as Frank McBrearty. By giving him this job, we are rewarding that behaviour,” he claimed.
In a recorded vote, councillors were asked to call out the name of the councillor they wanted to be Mayor.
The independents, Sinn Fein, Labour, Fine Gael got behind McBrearty.
Seventeen councillors backed McBrearty. Eleven backed Cllr Donaghey.
Cllr Donaghey spoke briefly to thank her party for the nomination before wishing Cllr McBrearty “all the best” for the year ahead.
There was a huge round of applause for Cllr McBrearty. Cllr Martin Farren (also Labour) was made Deputy Mayor despite Fianna Fail proposing Cllr Patrick McGowan.
In a recorded vote Cllr Farren won by the same margin as his party colleague – 17 to 11.
In his speech Cllr McBrearty thanked the councillors who elected him.
“I will work hard to promote Donegal and I want to support the issues of sport and mental health in my year in office,” he said.
He said sport can help families deal with the issues of mental health, admitting that he himself had suffered from depression.
Mayor McBrearty thanked the parties who supported him, but said: “I will work with all the parties over the next year.”
Earlier outgoing Mayor Noel McBride (Fine Gael) got a round of applause from all the council members when he thanked them and staff for their support throughout his year in office.
He said he had warned his family a year ago that they wouldn’t see a lot of him over the following 12 months.
“And I’m looking forward to getting home tonight,” he laughed.
All the parties paid tribute to Cllr McBride and his deputy Cllr Barry O’Neill with Sinn Fein’s Mick Quinn thankint them “for all the tremendous work you have done on behalf of the people of this county over the past year.”