Walsh urged all of Mary Byrne's fans to vote for the Dublin woman, describing her as a "glimmer of light on a bleak horizon".
He said: "Mary's cheering up the nation and she is putting us all in a better mood. That's why we need her to make it through this weekend, she'll be having her big homecoming party on Tuesday.
"She'll probably go home to Ballyfermot and we'll get her to Grafton Street too. It'll be a great party - we'll need it on budget day!"
The Mayo man also said that if Mary gets through to the final, it will change her life.
"It means an awful lot to me to get her through. I don't want Mary to be the one going home. It she can make it to the finals it will definitely change her life. She'll have the recording career she wants.
"I don't know if that can happen if she is eliminated."
He told the Irish Daily Star that Mary has become successful “against the odds”
"She's becoming a star against all the odds. Who would have thought a 50-year-old woman from Tesco would be knocking on the door of the finals of the X Factor?"