The programme, which has been broadcast at 11am since its launch in January, will move to the 2.15pm slot after Australian soap Home and Away.
Broadcast reports that the new time will allow the Tuesday and Thursday editions of the show to be broadcast live. The other three episodes will continue to be pre-recorded due to Feltz's commitments with the BBC.
The Vanessa Show has averaged just 100,000 viewers since it began - down from the 206,000 who watched Trisha Goddard in the same slot in the previous three months.
A Channel 5 spokesman commented: "Through the audience research we have carried out, it was felt that The Vanessa Show would work best in a mid-afternoon slot."
The Vanessa Show will begin to air at 2.15pm from Monday, March 7.