City Manager Bill Bruton said 187 people applied for the position, and three applicants were interviewed before he made the final decision.
Thompson will be paid $64,000 a year and reports to the city manager.
The public information officer should have the "ability to remain calm in a crisis or high-pressure situation," the job posting stated.
Thompson will now be the central source of information for Marietta, representing the city manager, City Council and department heads to other government agencies, businesses, media outlets and residents.
Thompson is used to grasping in-depth government policy and procedures after interning with former Gov. Sonny Perdue and working as a researcher and speechwriter for former Georgia House of Representatives Speaker Glenn Richardson.
Bruton said the city was lucky to have such a talented person as Thompson.
"She is highly regarded by those who worked with her at the state Legislature and her combination of experience, education and positive attitude will serve Marietta well," Bruton said.
A graduate of Georgia Tech, with a Bachelor of Science in international affairs, Thompson is a big Yellow Jackets fan and watches each football game either from Bobby Dodd Stadium or on television.
Raised in Gainesville, Thompson said she has stuck close to home in the metro Atlanta area, except for her time interning for then-Congressman Nathan Deal in Washington, D.C.
"The fact that it was still cold in June," Thompson said, was enough for her to realize she could not stay away from Georgia for an extended period of time.
A year ago, Thompson moved with her fiance, Mark Wiles, to Smyrna and said she is excited to be working in Marietta.
"I just think the Square is so cute," Thompson said. "It is a great place to come hang out on the weekend."