The 22-year-old Carmona was marching in support of political prisoner Leopoldo López in Valencia on Tuesday, when she was shot in the head by anonymous assailants on motorcycles.
She died Wednesday in the hospital.
Carmona, who had been named Miss Tourism 2013 for the state of Carabobo, was studying at university when she joined the protesters.
"She only needed one more semester to graduate," one of Carmona's relatives, speaking under anonymity, told Reuters.
Warning: Graphic image below.
Mauricio Ceneno-Notitarde / Reuters / Landov
"We are on the right side of history," he told supporters in a pre-taped statement released after his arrest. "We are on the side of justice."
Back in January, the pervasive crimes demonstrators are protesting against claimed the life of another Venezuelan beauty queen. Former Miss Venezuela and soap opera star Mónica Spear was killed by carjackers on Jan. 6, sparking nationwide outrage and mourning.
In Venezuela, the Washington Post noted, pageant winners like Spear and Carmona "are as revered ... as top athletes and movie stars."