Now, the Piano Man says he'll pen a new tune for the baby he and his new wife are expecting next month.
"I'm going to write a song for the kid, or something," he told Entertainment Weekly. "Alexa...was always enchanted with music even before there were words."
It likely won't be part of an album. Joel, 68, said last year that his 1993 album "River of Dreams" will be his last.
"That was really an homage," he said. "He's, like, the guy before me! He was the piano player before I was a Piano Man. I felt humbled by it -- to play [the Garden] 65 times and beat his record. I thought, 'I'd like to tip my hat to the man.'"
While the two have had had their ups and downs over the years -- with John publicly criticizing Joel for personal and professional reason, John said they buried the hatchet "a long time ago" during a sit-down meeting.
Asked to describe what that was like, John said, "He was concerned. I think he's a little scared of me sometimes, like 'What's he going to do?'"
Joel added with a laugh: "I'd tie his shoes [together] on stage while he [was] playing the piano, just to f*** him up."