Nottingham Crown Court heard Katie Crowder had deliberately scalded 19-month-old Gracie on 6 March at home and delayed getting help as she died.
Sally Howes QC said Gracie had suffered burns that covered 65% of her body and had been left for at least an hour.
The girl’s severe and extensive injuries could not have been caused accidentally, the prosecutor added.
A post-mortem examination gave Gracie’s cause of death as “scalds and thermal burns from exposure to hot liquid”.
Crowder, 26, of Wharmby Avenue, Mansfield, had denied murder but wept in the dock as she was convicted on Tuesday following a three-week trial.
She will be sentenced on 16 December.
The jury had heard Crowder appeared at her parents’ house nearby shortly before 06:30am holding Gracie in her arms, shouting “she’s dead”.
Paul and Karen Crowder said their daughter sounded “panicked” as she knocked on their door and they called an ambulance.
However Ms Howes said Gracie’s death was not instant and Crowder had delayed getting help to “cover her tracks”.
“She knew what she had done, cleaning up, cleaning away, thinking of what she could possibly say as an explanation,” she told the court.
She said the toddler’s injuries were not immediately life-threatening and had she received help straight away, she could have survived.
Experts had given evidence to say they believed it would have taken Gracie “in the region of an hour” to die from her injuries, and she would have been “screaming”.
Ms Howes also told jurors the amount of cocaine found in the defendant’s blood four hours later was consistent with Crowder taking the class A drug in the hour before Gracie’s death.
Crowder told the trial she had not heard anything and found Gracie lying on the bathroom floor next to a mop bucket.
She claimed she filled the bucket with hot water to clean up dog urine but then abandoned it in the bathroom to get changed and empty clothes from the washing machine.
Following the verdict, Det Ch Insp Rob Routledge said going to the post-mortem examination was “one of the most difficult things I’ve done”.
“Nobody likes to think a parent can do that to their own child,” he said.
He said the case was “one of the most unusual” he had worked on due to a lack of witnesses and CCTV.
“There is only one person who knows exactly what happened inside that house [Crowder], and it was the prosecution’s case she was not telling the truth,” he added.
“We knew there were inconsistencies in the story, but we had to prove that what Crowder said had happened couldn’t possibly have happened.
“Thankfully these cases are rare, but you never get hardened to a job like this.
“They aren’t injuries you will forget. That gave everyone determination to find out the truth. This case meant a lot to people.”