The 16-year-old, who will be seen opposite Barrymore in the upcoming romantic comedy The Familymoon, caught up with E! News at the Flaunt magazine Party at Hakassan in Beverly Hills.
When asked about Barrymore's second pregnancy, which was announced earlier this week, Thorne revealed that her costar is "ready" for the new addition to her family.
"I thought it was so great," the Shake It Up! star said. "She brought Olive on set and she is such a good mother and she was always with her baby staying up all hours of the night making sure she was comfortable."
Thorne dished that she sent the 38-year-old actress a bouquet of flowers when she heard about baby No.2.
"She loved it," Thorne said.
Barrymore's rep confirmed to E! News exclusively on Monday, Nov. 4, that she and her husband, Will Kopelman, are expecting their second child. They are already parents to 1-year-old daughter Olive.
The Flower Cosmetics creator stepped out with her family in West Hollywood on Sunday, Nov. 3 with a tiny baby bump.
—Reporting by Baker Machado