"Yes, it's true," the Victoria's Secret Angel, 29, tells PEOPLE. "My love proposed last month and I couldn't be happier!"
The California native is set to wed her longtime boyfriend, medical equipment sales rep Sean Clayton.
Clayton reportedly popped the question over Thanksgiving while the couple was visiting his parents in Ohio.
Ellingson, who has previously walked the runway for Chanel and Christian Dior, was spotted wearing a large diamond engagement ring on Tuesday at a screening of the Victoria's Secret Fashion Show in N.Y.C.
Reporting by MICHELLE TAN