The 'Lighthouse' group confirmed in October that they will go their separate ways after 14 years in the industry following a farewell tour next May.
X Factor judge and Westlife manager Walsh has now revealed that he is more interested in crafting a solo career for Filan over the 32-year-old's bandmates Kian Egan, Nicky Byrne and Mark Feehily.
Walsh told The Mirror: "I'm going to manage Shane Filan. He's going for the Michael Buble market. They're all good but I can only manage one. I love Shane's voice. I love Mark's voice too. The other boys are going to do TV and different stuff and radio. They are going out on a high.
"Shane is going to be a big artist. I will only manage someone if I believe in them. If I get someone amazing I will manage them."
Filan revealed in November that all the members of Westlife have considered a solo career.
Feehily has confirmed plans to continue making music on his own after the split.
> Westlife: 'Louis Walsh put us through hell'
> Westlife to split: Five career-defining songs - video
Watch Westlife in the video for 'Lighthouse' below: