Vishnevetsky is replacing the previously announced Elvis Mitchell, the show announced Tuesday. No explanation was given for Mitchell's departure.
The Russian-born Vishnevetsky, 24, writes for the film website Mubi and contributes to the Chicago Reader. He'll appear alongside co-host Christy Lemire, 38, film critic for The Associated Press.
Ebert lost his ability to speak after cancer surgeries, but will be on the weekly show with a segment in which he communicates with a computer-generated voice. He will executive produce the series in Chicago with his wife, Chaz Ebert.
"Ebert Presents At the Movies" premieres Jan. 21 on public TV stations.