The `Piano Man` singer - who split from third wife, chef Katie Lee Joel last year - is reportedly dating 29-year-old Alexis Roderick, who works for Morgan Stanley bank in New York after meeting her in a restaurant.
Explaining how they met, Alexis told the New York Daily News newspaper: "He was going to dinner. I wasn`t. And we were friends for a while before we started dating."
The pair were spotted together in September but this is the first time Alexis has acknowledged the relationship.
Billy was also previously married to his business manager Elizabeth Weber Small and supermodel Christie Brinkley, with whom he has a 24-year-old daughter Alexa Ray Joel.
Alexa revealed last year she was helping her 61-year-old father get over the ending of his third marriage and claimed he found it hard to trust people.
She said: "He was the first person that told me, being who he is, he can`t just trust everybody. I like knowing that my dad can talk to me in the same way that I come to him... I`m just supporting him right now."
Billy`s new girlfriend Alexis will be busy helping the singer recuperate after he recently underwent surgery on both hips.
He was admitted to hospital in Long Island, New York, last month to be treated for a congenial hip ailment and decided to have both joints looked at in order to stop himself backing out of later surgery.