The pre-show's executive producers Charlie Haykel and Juliane Hare made the announcement Monday.
This will be Smith's first time as host of the Oscar pre-show.
Menounos presided over the red-carpet show for the 76th Academy Awards, and Roberts and Gunn served as hosts of the arrivals show two years ago for the 81st Academy Awards.
"Oscar's Red Carpet Live" is to air on the ABC Television Network at 7 p.m. EST, immediately preceding the Oscar telecast Feb. 27 at the Kodak Theatre at Hollywood & Highland Center.
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