Tina Valdez, 37, reported her daughter missing to authorities in August, claiming the girl had run away and was searching for her father, Archer County Sheriff Ed Daniels said.
But last month, after US authorities had located and spoken to the teenager - who was in Mexico - Valdez told investigators she sold the girl, Daniels said. The alleged admission came while police were interviewing Valdez about filing a false report about her daughter being a runaway, he said.
Valdez and the man who allegedly bought her daughter, 35-year-old Jason Carlile, were indicted on Monday on charges of purchase or sale of a child, a third-degree felony, said district attorney Jack McGaughey.
Both are being held in jail.
Carlile also faces previous charges of indecency with a child and possession of child pornography..