Jurors deliberated for just one day before they found Stacey Barker, 26, guilty of assault on a child causing death and child abuse.
Barker told investigators she was knocked out, and her 18-month-old daughter was kidnapped in Lancaster in March 2009. But her cellphone records revealed she was in L.A. at the time.
Barker later admitted the child was dead and led investigators to her body in a weedy lot in Sylmar. She claimed her daughter's death was accidental, but investigators say the child was suffocated.
The Associated Press contributed to this story.