No other details were immediately available.
McCartney, 69, and Shevell, a 51-year-old New York businesswoman, have been dating since 2007. They got engaged in April with McCartney presenting his bride-to-be with a $650,000 ring.
"It will be a small, intimate wedding," the Web site quoted a source close to the couple, whose name was not reported, as saying. "It's going to be very elegant and classic. ... They are having a big party in New York to celebrate later on."
McCartney was married to photographer and animal-rights activist Linda McCartney for 30 years until her death from breast cancer in 1998.
He wed model Heather Mills in 2002, but that union officially ended in a high-profile divorce six years later.