Simon Cowell recently confirmed that Walliams will join him once again on the judging panel with Amanda Holden and Alesha Dixon next year.
The comedian said that the show had given him a "new lease of life", but joked that the eventual winner should receive a bigger prize next time.
"The most important thing is that me and Simon get engaged next series," he joked to The Mirror.
"Actually the most important thing is we find really talented people, because with those shows no matter how much amusement the judges are providing, or how fantastic Ant & Dec are being, you need to find someone at the end of it who's going to have a career afterwards.
"Those shows require a lot of a viewers' time so at the end someone's got to have won something. At least on Britain's Got Talent you win half a million pounds, which isn't bad, is it? I think Simon should make it a million, round it up."
He continued: "Britain's Got Talent gave me a whole new lease of life where people could see me as myself.
"It was nice to be me rather than a character in a sketch and it seemed to work, especially my relationship with Simon, seeing him laugh. We found some really great talent too.
"I'd come from doing sketches wearing wigs and make-up, and people don't really get to know you. But when you've not got a script, people start to see you as you.
"And it's a different kind of audience. Britain's Got Talent is much more of a family audience, so I felt like it was a reinvention for me."
David Walliams recently announced that he was expecting a baby with wife Lara Stone.
Speaking about being a father, he added: "I'm really looking forward to being a dad, the whole experience.
"I'm looking forward to seeing the baby for the first time, seeing this little person who's a mixture of you and the person you really love.
"But hopefully it will look like Lara and not Simon Cowell."
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