The wedding is taking place at Mar-a-Lago, Donald Trump's opulent seaside mansion in Palm Beach. The estate also hosted the billionaire's wedding to Slovenian model Melania Knauss in 2005.
Donald Trump, whom she divorced in 1990, is attending, as are their children.
"Ivanka is the maid of honor and her two sons are giving her away," Saxton said.
Also among the almost 600 guests expected are hotel heirs Rick and Kathy Hilton, the parents of Paris; and singer-songwriter Neil Sedaka.
Trump, 59, and Rubicondi, 36, have been together for about six years, Saxton said. They got engaged in September.