“The race was uncontested and the vote was unanimous,” Pheu Thai MP Wiphuthalaeng Phattanaphuthai said.
In her acceptance speech, Thida said she welcomed the opportunity to serve her fellow reds.
“I admit there is still a conflict within the movement but all core leaders are committed to the struggle,” she said.
She said she would overcome past flaws in order to continue and strengthen the struggle for democracy. She also pledged to improve the structure of the reds movement at the regional level.
Last week the red shirts organised a meeting to chart their course of activities, including the push for amending the charter. There were talks about leadership change and Thida indicated she would not cling to her position.
Certain factions in the movement voiced support for Pheu Thai MP Apiwan Wiriyachai to lead the red shirts. But he did not join the race.