Cromley, who was elected to this position for the next term, will fill the vacancy through the end of the year before beginning his elected term Jan. 1, 2017.
"I appreciate Bryan's willingness to serve during this important time," Tomblin said in a statement. "His commitment to his community and to the law is evident. I am confident he will serve with fairness and dedication."
Cromley received his undergraduate degree from West Virginia University in Economics prior to receiving his Juris Doctor from the Western Michigan University Thomas M. Cooley Law School.
He began his career as an extern then law clerk for the Honorable David W. Nibert of West Virginia's 5th Judicial Circuit Court. Cromley then opened his own practice and spent time with the Jackson County Prosecuting Attorney's Office as an Assistant Prosecutor.
"I'm deeply honored Governor Tomblin appointed me," Cromley said. "I look forward to serving the people of Jackson, Mason and Wirt Counties.
"I will strive to provide a fair and impartial court."
Throughout his career, Cromley's experience has included domestic relations, criminal offenses, juvenile abuse and neglect, juvenile delinquency and mental hygiene practice.