The 40-year-old singer - whose sun played drums during one of his parents concerts - showcased her sculpted arms while wearing a sparkling sleeveless dress at the function.
The songwriter - who recently accompanied her husband during a star-studded gala - donned a jewel-covered sheer dress that showed off her toned arms during the viewing party.
Katharine McPhee and David Foster's 3-year-old son, Rennie, made his stage debut on the drums during the couple's concert at the Kennedy Center in Washington, DC.