The 28-year-old model and 47-year-old singer attended the 2016 Glamour Women of the Year Awards in Los Angeles, where they were honored for their leadership and contributions to society.
Graham showed off her figure in a white bodysuit with beaded embellishment and sheer legs. Stefani stunned in an organza gown with a halter neck that bared her stomach and a short train.
"2016 was an interesting ride, but never before have I seen such size diversity in fashion, in film, on buses, on covers of magazines, in films, in TV. It's been absolutely incredible," she said.
"I didn't do it by myself. It takes a village," the star added before encouraging, "Don't let your body hold you back. Don't let your body insecurities hold you back from doing anything that you want to do."
"We need to work together to redefine the global image of beauty and continue to push for a more inclusive world. I'm thrilled Barbie had not only evolved their product, but also has continued to honor women who are pushing boundaries," the model said.
"It was important that the Barbie resembled me as much as possible," she added. "The thighs touching was one way to show young girls that it's okay for your thighs to touch, despite society saying that a 'thigh gap' is more beautiful."
Graham is known for her modeling work with Lane Bryant and Levi's, and became the first plus-size model to cover the Sports Illustrated Swimsuit Issue this year. Stefani last released the album This is What the Truth Feels Like in March.