The sentence came shortly after a Chatham County Superior Court jury convicted Newkirk, 35, on charges of felony murder, armed robbery and possession of a firearm during the commission of a felony.
The victim, Vipin Patel, 65, was shot once and slain Dec. 23, 2005, during a robbery of his Kwik Way Food Mart on U.S. 80.
Chatham County Superior Court Chief Judge Perry Brannen Jr. sentenced Newkirk to life in prison for the murder and tacked on an additional five years for possession of a firearm during commission of a crime.
The armed robbery charge merged with the murder count for purposes of sentencing.
Brannen refused a defense request that a charge of possession of a firearm by a convicted felon be sent to the jury.
He ruled there was no evidence to support the charge.
Brannen also rejected defense efforts to include lesser charges of voluntary manslaughter and theft by taking to the jury.
Assistant District Attorney Maria Waters introduced five prior felony convictions for Newkirk during the sentencing hearing.
"He'll never probably be released from prison in his lifetime," defense attorney Michael Schiavone told Brannen during this brief sentencing hearing.
Sentences were prescribed by Georgia law, a fact Brannen noted during sentencing.
During closing arguments Thursday, Waters told the jury Newkirk planned the robbery and fled carrying the store's cash register.
"Newkirk was one of the ringleaders," she said. "He wanted money."
The prosecutor told jurors Newkirk directed his cohorts to shoot Patel.
But, Schiavone told jurors his client was being unfairly treated by the prosecutors.
"My client didn't get the choice to be there," Schiavone said, "My client is the non-shooter. He is not the guy in this case. He is not Hector Gibson."
Gibson has been convicted as the triggerman in the case.
The defense argued prosecutors made deals with three other non-shooters for voluntary manslaughter but is treating Newkirk differently.
"Harry Newkirk should not pay a greater price than the other non-shooters," Shivavone said.
It took the 10 women and two men less than two hours to return the convictions.
Newkirk stood emotionless as the verdicts were read in open court.