The mum was seen calmly pushing the child onto the beach in her pushchair, and stands accused of leaving her there to drown in the rising tide of the English Channel.
The Mirror reports that Fabienne Kabou, 36, from Senegal, went missing for nine days after the girl's body was found by fishermen in the coastal town of Berck-sur-Mer, northern France.
The mum was arrested on Friday after a public appeal was made to locate her.
Prosecutors in the case say that Kabou admits she travelled with her daughter to Berck-sur-Mer from Paris with the intention of killing her.
"She left the child alive on the beach as the tide was rising," the prosecutor said.
Kabou's lawyer Fabienne Roy-Nansion said the mum 'realises what she has done'.
"She expresses remorse. She is not trying to find excuses".
Images captured at the time show the child strapped in to her stroller, her hood up on her coat, as her mum pushed her onto the sandy beach.
Kabour faces life in jail if found guilty.