He and Brinkley were married from 1985 to 1994, and share 29-year-old daughter Alexa Ray Joel.
Brinkley and Mellencamp were first linked in mid-September, and were spotted again on a second date the same week. News at the time the pair are "spending time together" following Mellencamp's split from actress MegRyan.
"And now she's datingJohnMellencamp," he said after finishing his 1983 hit "The Longest Time," which was inspired by Brinkley.
Joel is known for adding good-natured asides to the end of songs inspired by exes.
I love the person I’ve become, the one I’ve evolved into.