Moore, who had pleaded not guilty to the charges, stood motionless as the jury delivered its verdict on Saturday afternoon.
"There was a mountain of evidence against Mr. Moore," said homicide Det. Sgt. Hank Idsinga outside the courtroom, adding Moore made numerous mistakes that led back to him during his shooting "rampage."
That rampage began when Jahmeel Spence was shot dead in September 2010 near his mother-in-law's house.
Later that month, Mike James and Courthney Facey died in a drive-by shooting, slain by bullets fired from the same gun.
In November of that year, Carl Cole was shot to death with that same handgun.
On Saturday, Spence's family celebrated quietly inside the courtroom after the verdict was read.
Moore will be sentenced at a later date.