Jurors deliberated for about 4? hours Thursday before convicting 39-year-old Aric Woodard of York in the November 2011 death of 2-year-old Jacques Twinn.
York County prosecutors, who are seeking the death penalty, allege that Woodard beat the boy while looking after him at a York home.
Defense attorney Joanne Floyd argued that it wasn't clear when the injuries were inflicted or who inflicted them
After jurors left the courtroom, Woodard faced prosecutors, clapped his hands and said "Good job, good job."
Jurors will return Monday to begin hearing arguments on whether Woodard should be sentenced to death or to life in prison without possibility of parole.