McElhatton is leading ATG's team of six journalists as the 44-year-old title evolves online and into new markets. She is only the fourth editor of ATG since the publication was launched in 1971.
A business journalist and editor for more than 20 years, McElhatton spent 12 years at Haymarket Media Group editing marketing and digital magazines. She was most recently head of content at a communications agency.
Matt Ball, ATG's publishing director, said: "Noelle shone through a strong line-up of candidates for the role, because of her experience as a multi-platform business magazine editor and her keen interest in antiques. She will influence and implement our development plans as we embark on the next phase of the Gazette's growth."
McElhatton, who collects antique Irish silver, said: "Becoming editor of the Antiques Trade Gazette, the world's leading weekly title covering the antiques and art markets, is an enormous privilege and responsibility.
"In particular, I look forward to working with its expert team of journalists, renowned for their knowledge and passion for this business."