Morrison, 24, who has had five Top 10 hits including a number one last summer, was convicted of the charges which related to an incident outside a 24-hour supermarket in west London last October as he returned home with friends at 4.30am, after an evening spent nightclubbing.
Plain-clothes police officers initially believed he had been planning a robbery and moved to arrest him as he left the shop and walked towards his chauffeur- driven Mercedes.
Detective Constable John Cushion told the court Morrison turned to him, raising his right hand which was holding the stun gun.
"I feared he was going to fire the gun into my body and I hit him on the head with my radio," said the officer. "He was trying to use the gun on me but I struggled with him and prevented it."
Morrison admitted to Marylebone Magistrates Court in west London that he had possessed the illegal stun gun, which he bought in the US for his own protection. It can deliver a charge of 23,000 volts, causing "involuntary muscle contraction, pain, shock, a loss of balance and mental confusion".
The singer denied using threatening behaviour and said he feared for his life. He felt "insulted" and "disrespected" after being accused of robbery.
Stipendiary magistrate David Kennett-Brown told the pop star: "These very serious offences can only be properly dealt with by way of a custodial sentence." Sentencing was adjourned until 14 May. Leaving court amid a posse of minders, a pair of celebrity sunglasses could not hide his tears.
Maybe Morrison's recent stage performances were tempting fate. They involved him brandishing handcuffs, backed by female dancers clad as mini-skirted policewomen. Matthew Brace