According to The Sacramento Bee, Ka Yang, 26, placed her daughter, Mirabelle Thao-Lo, in the microwave at her home in California.
The infant was in the microwave for 2½ to 5 minutes, authorities said.
Mirabelle had 60 per cent burns from head to toe, as well as radiation burns to her internal organs.
Her mother initially attempted to cover up her crimes, insisting that she had been holding the baby girl at the computer when she lost consciousness during an epileptic seizure.
This, she said, had caused Mirabelle to fall to the floor and become burned by a heater.
However paramedics did not find her to be disoriented when they arrived, and detectives found many inconsistencies in her story.
When they later discovered Mirabelle’s dummy inside the microwave, Yang acknowledged that she had lied - although she suggested that this could be the result of a split personality.
Ka Yang, 36, is now facing a 26 year prison sentence for murder and assault.
She is scheduled to be sentenced in December, and her three young sons are in the care of relatives, the Sacramento County District Attorney's Office said.
Her lawyer, Linda Parisi, has stated that she is disappointed with the verdict, insisting that the mum-of-four did not deliberately kill her child.
"There is no history of child abuse.
"She has no criminal history."