Nahmias will replace Leah Ward Sears, the former chief justice of the state court who stepped down in June.
Nahmias was appointed U.S. attorney in Atlanta in 2004 by President Bush.
He helped lead the prosecution of Olympic Park bomber Eric Robert Rudolph and former Atlanta Mayor Bill Campbell.
He also recently earned victories in cases involving two high-profile terror suspects.
Nahmias is an Atlanta native and a graduate of Harvard Law School. He also clerked for U.S. Supreme Court Justice Antonin Scalia.