"A wonderful evening at home," Streisand captioned a photo of the group on Twitter.
— Barbra Streisand (@BarbraStreisand) August 23, 2015
Gaga, 29, posted a similar group photo on Instagram. "Saturday Night Fever with some wonderful new friends," she wrote.
The younger singer also took the opportunity to strike a pose with the veteran performer.
"Barbra and me. what a completely amazing woman. #Funnygirls," Gaga wrote on Instagram.
Earlier this year, Gaga paid homage to another legendary singer, Julie Andrews, with her "Sound of Music" medley at the Oscars. Andrews told ABC News she now calls Gaga, a "very new good friend."