The 25-year-old singer reportedly proposed to Indian actress Priyanka in late July after just two months of dating, and the couple finally confirmed the rumours with sweet Instagram posts last month.
The couple celebrated at an engagement party hosted by the bride-to-be's relatives in Mumbai, where Priyanka, 36, wore a traditional yellow sari with white embroidery, and Nick donned a white tunic.
And during his appearance on "The Tonight Show Starring Jimmy Fallon" on Friday, September 07, he reminisced about their romantic trip.
"After we got engaged, we went to India, to her home country, to Mumbai, and my parents came along. We did this beautiful Roka ceremony... It's a confirmation from both sides of the family that they approve of the engagement," he explained.
"There's some beautiful prayers and a connection just for the family to have a chance to meet and hang out. It's really incredible."
The singer stressed that both he and the "Baywatch" star were keen to keep their engagement private before sharing their happy news with their fans.
"We both left that ceremony so full of joy," Nick added. "For she and I, I think it was just nice to have that time with the family first. Have that private moment then be able to share with the world afterwards."
The couple was recently spotted on a double date with Nick's brother Joe Jonas and his fiancee Sophie Turner at the U.S. Open in New York, and also attended the Ralph Lauren New York Fashion Week show on Friday.
Nick shared a black-and-white snap of him holding hands with his stunning fiancee, and later posted a photo of them meeting the iconic designer himself at the high-fashion event.