The X Factor USA judge's father Alfonso Valiente was quoted in yesterday's Mail on Sunday as saying: "You know about the proposal? Yes, they are engaged. My future son-in-law is a really nice guy, really down-to-earth. My family all like him."
She has been dating Formula 1 driver Hamilton for three years, although the couple briefly separated in 2010.
Scherzinger is currently preparing for the US television premiere of The X Factor on September 21.
Hamilton, who won the Formula 1 world championship in 2008, is currently in fourth place in the world drivers' championship with 109 points.
He makes a voice cameo in Disney Pixar's Cars 2, which is released in the UK this Friday.