Witherspoon, 39, took to Instagram to share a photo of her, Ava and Betty each holding an ice cream.
"The best way to enjoy #gelato??? #ThreeGenerations," she captioned it.
In the photo, the "Legally Blonde" actress donned a cream hat with red ribbon, a sleeveless floral print dress and a black shoulder bag.
Ava sported a printed off-the-shoulder dress with white lace. Her hair was styled in a side braid. Betty, meanwhile, wore black aviators, long-sleeved top and beige trousers.
During their trip, Witherspoon and her daughter had a dinner with famous designer Valentino Garavani.