The singers arrived at the Friars Club event separately but left The Waldorf Astoria hotel holding hands. Mayer was also seen clutching a small gift bag from luxury jewellery company Tiffany & Co.
The public display comes after Perry told the July (13) issue of Vogue that she and Mayer were "over", adding, "I was madly in love with him. I still am madly in love with him. All I can say about that relationship is that he's got a beautiful mind."
The stars, who split for a second time earlier this year (13), first sparked reunion rumours when they were spotted together at a barbecue Perry held at her Hollywood Hills home in Los Angeles in May (13).