"The Perfect Man" leading lady and "The Hot Chick" leading man will hand out awards such as Choice Liplock, Choice Movie Chemistry and Choice Male Hottie during the Los Angeles ceremony Aug. 16.
Gwen Stefani will kickoff the show with a performance of "Hollaback Girl" and will also be honored with the Teen Choice Visionary Award.
Duff, 18, won Choice Movie Breakout Performance in 2003 for her role in "The Lizzie McGuire Movie." She recently starred in the films "Raise Your Voice" and "A Cinderella Story." Her third pop album "Most Wanted" will debut next month.
Schneider, 41, is best known as "Deuce Bigalow: Male Gigolo," a role he'll reprise in the upcoming sequel "Deuce Bigalow: European Gigolo." The "Saturday Night Live" veteran was most recently seen on the big screen in "The Longest Yard."