Liberal senator Alex Antic has defeated SA Upper House leader Nicola Centofanti in a ballot of Liberal Party delegates.
State president is an internal role roughly equivalent to chair of a company board, overseeing campaign preparations and setting meeting agendas.
Liberal Party state director Alex Hyde confirmed the presidency this morning, although the margin of victory is yet to be published.
Liberal senator Alex Antic has been elected president of the South Australian Liberal Party.
The right-wing backbencher, who has praised members of One Nation and repeatedly crossed the floor against the Coalition, defeated SA Upper House leader Nicola Centofanti in a ballot of Liberal Party delegates on Saturday morning.
He has previously vowed to give Liberal members a "genuine say in the policy direction" of the party.
The ABC has previously reported that the prospect of an Antic presidency has led some in the party to discuss federal intervention to take over management of the SA division.
Ms Centofanti, a non-Antic aligned conservative, had the backing of moderates and conservatives who wanted to stop an Antic presidency.
But his support among the party's roughly 200 State Council delegates follows a five-year recruitment drive led by Antic in local party branches.
Liberal Party state director Alex Hyde confirmed Senator Antic's presidency this morning, although the margin of victory is yet to be published.
"The new president will convene the state executive soon and we all look forward to getting on with the job," Mr Hyde said in a statement.
Senator Antic has been a prominent vaccine sceptic in the parliament and has expressed admiration for US President Donald Trump.
He has also praised One Nation members of parliament and argued a post-election coalition with the party should not be ruled out.
His alignment with One Nation on certain policy matters has led to speculation he could defect to the party if he lost the presidency.
One Nation SA leader Cory Bernardi, who was pictured sharing a beer with Antic during the March state election campaign, said on Friday he would "welcome Alex Antic into One Nation in a flash".
"I'd welcome him at any turn. He's a great political talent," he told 891 ABC Adelaide.
Senator Antic has not yet commented on his election as state president and media were not allowed in for the proceedings of the Liberal Party's AGM.
In a pre-meeting pitch to delegates, he wrote that he would "restore policy authority to members" if elected president — something which could pose a challenge to SA Liberal leader Ashton Hurn.
"We need economic action on inflation, housing and energy without surrendering to net-zero orthodoxy and we need to stand up for the cultural inheritance of this country," he wrote.
"We also need to treat the One Nation challenge as the warning it is.
"Not by copying every One Nation position, but by proving that the Liberal Party can once again be the vehicle for the values that made voters want to vote blue."