Brian Jean, a 52-year-old lawyer from Fort McMurray, Alberta, defeated two challengers to become the new leader of the Wildrose Party.
"I'm very happy. I'm very excited. I'm very humbled by the trust you've placed in me tonight," said Jean who resigned from federal politics last year.
"I actually regard it as a sacred trust," he said to several hundred cheering supporters in Calgary.
Twice during his victory speech, Jean choked back tears while speaking about his son, Michael, who died of cancer earlier this month during the thick of the leadership campaign.
He thanked others who continued to campaign when he couldn't in order to spend time with his family.
"Mikey was a very, very special person. When cleaning his room this week, I found a handwritten note on the table beside his bed," Jean told party members on Saturday.
"He wrote in his own handwriting, 'What you do for yourself dies with you, but what you do for others remains and is immortal.'"
The Wildrose leadership race became necessary when former leader Danielle Smith and eight Wildrose colleagues crossed the floor to join the ruling Progressive Conservative Party, leaving Wildrose with just five seats.
Jean, who will run in Fort McMurray, edged out current Wildrose member Drew Barnes and former Strathcona County mayor Linda Osinchuk.
Members voted by telephone ballot for the last 13 days.
According to the leadership committee chair, 35 per cent of the party's 25,000 members voted, and Jean took 55 per cent of the ballots cast.
Jean, who represented a northern Alberta riding in the House of Commons between 2004 and 2014, said he intends to keep the government of Premier Jim Prentice honest.
But he is under no illusions about forming government.
"I don't look at a probability right now that we are going to form government in the next election. I believe we will win a strong mandate from the people, a strong mandate is what we need," Jean told reporters.
"I don't think Albertans are ready for us to win. I think Albertans want a strong opposition but they are not prepared to elect us."
Prentice issued a statement congratulating his former caucus colleague.
"We will not always agree on issues in the weeks and months ahead. For today, let me congratulate Brian on having earned these new responsibilities, and for his ongoing commitment to public service," said Prentice.
Calgary political scientist David Taras predicted Jean would probably win, but doubts a new leader will make much of a difference with the voting public.
"The downside is the vast majority of Albertans couldn't pick him out of a lineup and his views are too far to the right for most Albertans," said Taras from Mount Royal University.
"The party is in disarray and has very little time to get its house in order. But at least they will finally have a leader."
—With files from Rob Drinkwater in Edmonton
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