In a unanimous decision on Thursday, the jury found Dial guilty of voluntary manslaughter, possessing an instrument of crime and recklessly endangering another person.
He was found not guilty of charges of third-degree murder and official oppression.
At the heart of the case was whether Dial was justified in using deadly force when he fired six shots into a car driven by Eddie Irizarry in August 2023, killing him.
Dial took the stand in his own defense on Wednesday, at times tearful as he told the jury he feared for his life.
"We've said all along Mark made a mistake. We went to trial on 3rd degree murder, and we're thrilled the jury saw this was not a malicious killing; this was a mistake. This was a mistake that the jury found was not reasonable under the circumstances," said Fortunato N. Perri, who represented Dial.
Police started following Irizarry after he drove erratically and eventually went the wrong way down East Willard Street.
After Irizarry stopped his car, he sat inside holding a knife.
Philadelphia officer charged with murder in shooting death of Eddie Irizarry; bodycam video released
The defense said the handle resembled a gun, and it looked as if he pointed it at officers. Dial testified he thought his partner yelled "gun."
Throughout the trial, Irizarry's family has been emotional, leaving the court at times as the bodycam video was shown of him being killed.
"A little comfort. It's not going to bring Eddie back, but at least now everyone in Philadelphia can see there is some type of justice. Sitting in that courtroom today was really frustrating, but at the same time, the jury did what was right," said Irizarry's aunt, Zoraida Garcia, after the verdict was read.
They say this should have been a simple traffic stop, not a shooting.
In response to the verdict, District Attorney Larry Krasner said in a statement, "While we believe most sworn law enforcement personnel carry out their responsibilities with integrity and professionalism, we believe today's conviction of former Philadelphia Police Officer Mark Dial was both fair and just."
Dial is now a convicted felon and can never work as a police officer again. Family members say they're hoping for jail time as well.
Prosecutors requested that bail be revoked, however, that was denied by the judge.
Sentencing is scheduled for July 17.