Simpson, 29, made the jubilant announcement on Monday via Twitter, posting a photo of the two — and her huge sparkler! -- with the caption: "My baby love and I are ENGAGED!!! Hallelujah Hawaii !!!!!"
Ross, 25, posted the same photo on his account captioning it: "The love of my life said YES!!!!!!"
Simpson's new fiancé is the son of famed singer Diana Ross and the two went public with their romance last July.