Miley, who recently launched her Hannah Montana movie in London, and Nick gazed into each other's eyes and embraced as they sang duet, Before The Storm, at a show in Arlington, Texas.
Afterwards, the 16-year-old chanteuse posted on Twitter: "In one of my favourite cities with my favourite people. Guess where I am and what I'm doing. I will never tell :)".
She later followed it up with: "@mileycyrus had an awesome time with @jonasbrothers last night. The show was awesome :) I miss you already :(".
The star has been spotted hanging out with her 16-year-old ex on numerous occasions since splitting with model Justin Gaston earlier this month. She says they're just "best friends", however.
So what's the story with Twitter…? In case you haven't already discovered it, Twitter is a free social networking service which enables users to send and read other users' messages. These 'tweets' are displayed on the user's profile page and delivered to other users who have subscribed to them. Since it launched in 2006, the service has become a hit with celebs. Check out hellomagazine.com's celebrity Twitter page