Tom Bell, aged 21, was gunned down at the Maple Tree on the Woodfield Plantation estate, Balby, at around 9pm yesterday.
He was given emergency first aid at the scene and rushed to hospital but could not be saved.
The family pub, at the heart of a new housing development, was placed on lockdown in the immediate aftermath of the shooting, with everyone ushered into the beer garden while paramedics battled to save Tom.
Witnesses provided police statements at the scene to help officers piece together exactly what happened.
Bullet holes can be seen in two of the pub windows this morning, which are sealed up to preserve potential forensic evidence at the crime scene.
The pub has been sealed off and police officers are standing guard.
South Yorkshire Police confirmed there was a fatal shooting but no other details have yet been released.
The force has not been disclosed whether any arrests have been made or if the armed killer is still at large.
Anyone with information should call South Yorkshire Police on 101.