Angry with his girlfriend's four-year-old daughter for defecating on a mattress, he grabbed her faeces and smeared it on her face.
This caused her to eat some of her own waste in the incident last November.
Even after her mother, 32, intervened and took her to the bathroom to clean her up, Mohammad Rudy Madon, 37, could not control his rage.
As the girl sat on a mattress, the former army regular punched and stepped on her right thigh several times, fracturing her bone.
He pleaded guilty on Tuesday to one count of child abuse, two counts of voluntarily causing grievous hurt and three drug-related charges.
Five other similar charges will be taken into consideration for his sentencing on Oct 10.
The mother and daughter cannot be named to protect the victim's identity.
Deputy Public Prosecutor (DPP) Rachel Lee told the court that on another occasion late last year, Mohammad Rudy also twisted the girl's right ankle, causing another fracture.
It was not mentioned why he had done so.