The Jealous hitmaker, 23, and Almost Famous beauty Hudson, 36, were photographed side-by-side riding a rollercoaster at Disney World in Orlando on Saturday (26Sep15), and hours later, she attended his concert at the House of Blues.
The next day (27Sep15), they were snapped enjoying a brunch together in Miami, where he had performed later in the evening.
Sources tell TMZ.com the two are not dating, but definitely "hooking up".
This is the second time Hudson has attended one of Jonas' shows - earlier this month (Sep15), she was in the audience for his New York City gig, alongside model Kendall Jenner and Jennifer Lopez.
Hudson clearly finds musicians attractive - her ex-husband is former Black Crowes frontman Chris Robinson and her former fiance Matt Bellamy of Muse. She has kids from both relationships.
Meanwhile, Jonas split from his Olivia Culpo, his beauty queen girlfriend of two years in June (15).