The suspect is said to have lured the victim into his home, before allegedly committing the crimes.
A 20-year-old man is being detained at Entebbe Police Station following his arrest over alleged defilement.
He is being held for reportedly defiling and then strangling to death a four-year-old child Thursday last week.
The suspect, who resides in Entebbe Municipality, is said to have lured the victim into his home, the scene of the alleged crimes.
Kampala Metropolitan Police spokesperson Patrick Onyango confirmed the arrest of the suspect, who is being charged with aggravated defilemement and murder. He is expected to appear in court next week.
Investigations into the crime are under way.