The 23-year-old singer and actor discussed the 37-year-old actress on Monday's episode of The Ellen DeGeneres Show after being spotted with Hudson prior to the Met gala last week.
"She's great," Jonas said of the Mother's Day star. "It was great, we had a group dinner the night before the Met gala. Lots of people. She was there and I was there. It was a group."
Jonas and Hudson were first linked in October and have been seen together several times since. The singer insisted he is single, however, when DeGeneres inquired about his relationship status.
"I really am [single]," the actor said after revealing he and brother Joe Jonas recently moved in together in Sherman Oaks, Calif.
Jonas also insisted he's single in the February/March issue of Complex magazine, but gushed about Hudson in the interview. He previously dated Olivia Culpo, while Hudson split from Matthew Bellamy in 2014.
"Kate's incredible," the actor said. "We had an unbelievable connection as two humans who just admire things about each other, and see something in each other that's beautiful."
"Out of my best effort to respect her and her privacy, I'm not going to say if we had sex or not," he added. "But we did have a beautiful connection. Even now I have so much admiration and respect. She's amazing."
Hudson called Jonas "a great guy" while discussing her book Pretty Happy in February. The actress will next appear in Deepwater Horizon, while Jonas will kick off his Future Now tour with Demi Lovato in June.