De Bruyne has made just two Premier League starts for Chelsea since returning from a loan spell with Werder Bremen, and Wilmots has advised the 22-year-old to seek a move back to Germany if he can't impress Jose Mourinho at Stamford Bridge.
The 44-year-old told Sport-Bild: "My request is that Kevin de Bruyne plays regular first-team football. Everyone knows what he is capable of.
"Schalke is a special club for me and it would be great to see a player of this quality play for Schalke 04.
"Kevin de Bruyne is a player that many clubs are about to consider."
De Bruyne has scored four goals in 17 appearances for his national side, and he is expected to feature for Belgium at the World Cup next summer.